patch: option --if-exists for pg_dump

commit 7c79aa77ccf53252bac8ce2302a7a0f7a1942e9b
Author: Pavel Stehule <pavel.stehule@gooddata.com>
Date:   Fri Dec 20 20:13:00 2013 +0100

    inital

diff --git a/doc/src/sgml/ref/pg_dump.sgml b/doc/src/sgml/ref/pg_dump.sgml
index 8d45f24..18f7346 100644
--- a/doc/src/sgml/ref/pg_dump.sgml
+++ b/doc/src/sgml/ref/pg_dump.sgml
@@ -650,6 +650,16 @@ PostgreSQL documentation
      </varlistentry>
 
      <varlistentry>
+      <term><option>--if-exists</option></term>
+      <listitem>
+       <para>
+        It use conditional commands (with <literal>IF EXISTS</literal>
+        clause) for cleaning database schema.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><option>--disable-dollar-quoting</></term>
       <listitem>
        <para>
diff --git a/doc/src/sgml/ref/pg_dumpall.sgml b/doc/src/sgml/ref/pg_dumpall.sgml
index 5c6a101..670539e 100644
--- a/doc/src/sgml/ref/pg_dumpall.sgml
+++ b/doc/src/sgml/ref/pg_dumpall.sgml
@@ -301,6 +301,16 @@ PostgreSQL documentation
      </varlistentry>
 
      <varlistentry>
+      <term><option>--if-exists</option></term>
+      <listitem>
+       <para>
+        It use conditional commands (with <literal>IF EXISTS</literal>
+        clause) for cleaning database schema.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><option>--inserts</option></term>
       <listitem>
        <para>
diff --git a/doc/src/sgml/ref/pg_restore.sgml b/doc/src/sgml/ref/pg_restore.sgml
index 717da42..dd8e990 100644
--- a/doc/src/sgml/ref/pg_restore.sgml
+++ b/doc/src/sgml/ref/pg_restore.sgml
@@ -490,6 +490,16 @@
      </varlistentry>
 
      <varlistentry>
+      <term><option>--if-exists</option></term>
+      <listitem>
+       <para>
+        It use conditional commands (with <literal>IF EXISTS</literal>
+        clause) for cleaning database schema.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><option>--no-data-for-failed-tables</option></term>
       <listitem>
        <para>
diff --git a/src/bin/pg_dump/pg_backup.h b/src/bin/pg_dump/pg_backup.h
index 6927968..83f7216 100644
--- a/src/bin/pg_dump/pg_backup.h
+++ b/src/bin/pg_dump/pg_backup.h
@@ -113,6 +113,7 @@ typedef struct _restoreOptions
 	char	   *superuser;		/* Username to use as superuser */
 	char	   *use_role;		/* Issue SET ROLE to this */
 	int			dropSchema;
+	int			if_exists;
 	const char *filename;
 	int			dataOnly;
 	int			schemaOnly;
diff --git a/src/bin/pg_dump/pg_backup_archiver.c b/src/bin/pg_dump/pg_backup_archiver.c
index 63a8009..327ff03 100644
--- a/src/bin/pg_dump/pg_backup_archiver.c
+++ b/src/bin/pg_dump/pg_backup_archiver.c
@@ -55,7 +55,8 @@ static ArchiveHandle *_allocAH(const char *FileSpec, const ArchiveFormat fmt,
 	 const int compression, ArchiveMode mode, SetupWorkerPtr setupWorkerPtr);
 static void _getObjectDescription(PQExpBuffer buf, TocEntry *te,
 					  ArchiveHandle *AH);
-static void _printTocEntry(ArchiveHandle *AH, TocEntry *te, RestoreOptions *ropt, bool isData, bool acl_pass);
+static void _printTocEntry(ArchiveHandle *AH, TocEntry *te, RestoreOptions *ropt,
+								 bool isData, bool acl_pass);
 static char *replace_line_endings(const char *str);
 static void _doSetFixedOutputState(ArchiveHandle *AH);
 static void _doSetSessionAuth(ArchiveHandle *AH, const char *user);
@@ -234,6 +235,7 @@ RestoreArchive(Archive *AHX)
 	bool		parallel_mode;
 	TocEntry   *te;
 	OutputContext sav;
+	
 
 	AH->stage = STAGE_INITIALIZING;
 
@@ -409,8 +411,24 @@ RestoreArchive(Archive *AHX)
 				/* Select owner and schema as necessary */
 				_becomeOwner(AH, te);
 				_selectOutputSchema(AH, te->namespace);
-				/* Drop it */
-				ahprintf(AH, "%s", te->dropStmt);
+
+				if (*te->dropStmt != '\0')
+				{
+					if (ropt->if_exists)
+					{
+						int		desc_len = strlen(te->desc);
+
+						/* Clause IF EXISTS can be used yet (by pg_dump) */
+						if (strncmp(te->dropStmt + desc_len + 5, " IF EXISTS", 9) != 0)
+							ahprintf(AH, "DROP %s IF EXISTS %s",
+											  te->desc,
+										  te->dropStmt + 6 + desc_len);
+						else
+							ahprintf(AH, "%s", te->dropStmt);
+					}
+					else
+						ahprintf(AH, "%s", te->dropStmt);
+				}
 			}
 		}
 
@@ -2938,9 +2956,35 @@ _getObjectDescription(PQExpBuffer buf, TocEntry *te, ArchiveHandle *AH)
 		strcmp(type, "OPERATOR CLASS") == 0 ||
 		strcmp(type, "OPERATOR FAMILY") == 0)
 	{
-		/* Chop "DROP " off the front and make a modifiable copy */
-		char	   *first = pg_strdup(te->dropStmt + 5);
-		char	   *last;
+		char	    *first;
+		char	    *last;
+
+		/* try to search IF EXISTS in DROP command */
+		if (strstr(te->dropStmt, "IF EXISTS") != NULL)
+		{
+			char buffer[40];
+			size_t   l;
+
+			/* IF EXISTS clause should be optional, check it*/
+			snprintf(buffer, sizeof(buffer), "DROP %s IF EXISTS", type);
+			l = strlen(buffer);
+
+			if (strncmp(te->dropStmt, buffer, l) == 0)
+			{
+				/* append command type to target type */
+				appendPQExpBufferStr(buf, type);
+
+				/* skip first n chars, and create a modifieble copy */
+				first = pg_strdup(te->dropStmt + l);
+			}
+			else
+				/* DROP IF EXISTS pattern is not appliable on dropStmt */
+				first = pg_strdup(te->dropStmt + 5);
+		}
+
+		else
+			/* IF EXISTS clause was not used, simple solution */
+			first = pg_strdup(te->dropStmt + 5);
 
 		/* point to last character in string */
 		last = first + strlen(first) - 1;
@@ -2961,7 +3005,8 @@ _getObjectDescription(PQExpBuffer buf, TocEntry *te, ArchiveHandle *AH)
 }
 
 static void
-_printTocEntry(ArchiveHandle *AH, TocEntry *te, RestoreOptions *ropt, bool isData, bool acl_pass)
+_printTocEntry(ArchiveHandle *AH, TocEntry *te, RestoreOptions *ropt, bool isData,
+								      bool acl_pass)
 {
 	/* ACLs are dumped only during acl pass */
 	if (acl_pass)
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 837e784..200ef9d 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -140,6 +140,7 @@ static int	no_security_labels = 0;
 static int	no_synchronized_snapshots = 0;
 static int	no_unlogged_table_data = 0;
 static int	serializable_deferrable = 0;
+static int	if_exists = 0;
 
 
 static void help(const char *progname);
@@ -349,6 +350,7 @@ main(int argc, char **argv)
 		{"disable-dollar-quoting", no_argument, &disable_dollar_quoting, 1},
 		{"disable-triggers", no_argument, &disable_triggers, 1},
 		{"exclude-table-data", required_argument, NULL, 4},
+		{"if-exists", no_argument, &if_exists, 1},
 		{"inserts", no_argument, &dump_inserts, 1},
 		{"lock-wait-timeout", required_argument, NULL, 2},
 		{"no-tablespaces", no_argument, &outputNoTablespaces, 1},
@@ -577,6 +579,9 @@ main(int argc, char **argv)
 		exit_nicely(1);
 	}
 
+	if (if_exists && !outputClean)
+		exit_horribly(NULL, "option --if-exists requires -c/--clean option\n");
+
 	/* Identify archive format to emit */
 	archiveFormat = parseArchiveFormat(format, &archiveMode);
 
@@ -809,6 +814,7 @@ main(int argc, char **argv)
 	ropt->dropSchema = outputClean;
 	ropt->dataOnly = dataOnly;
 	ropt->schemaOnly = schemaOnly;
+	ropt->if_exists = if_exists;
 	ropt->dumpSections = dumpSections;
 	ropt->aclsSkip = aclsSkip;
 	ropt->superuser = outputSuperuser;
@@ -890,6 +896,7 @@ help(const char *progname)
 	printf(_("  --disable-dollar-quoting     disable dollar quoting, use SQL standard quoting\n"));
 	printf(_("  --disable-triggers           disable triggers during data-only restore\n"));
 	printf(_("  --exclude-table-data=TABLE   do NOT dump data for the named table(s)\n"));
+	printf(_("  --if-exists                  use IF EXISTS when dropping objects\n"));
 	printf(_("  --inserts                    dump data as INSERT commands, rather than COPY\n"));
 	printf(_("  --no-security-labels         do not dump security label assignments\n"));
 	printf(_("  --no-synchronized-snapshots  do not use synchronized snapshots in parallel jobs\n"));
@@ -2290,7 +2297,8 @@ dumpDatabase(Archive *fout)
 
 	}
 
-	appendPQExpBuffer(delQry, "DROP DATABASE %s;\n",
+	appendPQExpBuffer(delQry, "DROP DATABASE %s%s;\n",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(datname));
 
 	dbDumpId = createDumpId();
@@ -7894,7 +7902,9 @@ dumpNamespace(Archive *fout, NamespaceInfo *nspinfo)
 
 	qnspname = pg_strdup(fmtId(nspinfo->dobj.name));
 
-	appendPQExpBuffer(delq, "DROP SCHEMA %s;\n", qnspname);
+	appendPQExpBuffer(delq, "DROP SCHEMA %s%s;\n",
+						    if_exists ? "IF EXISTS " : "",
+						    qnspname);
 
 	appendPQExpBuffer(q, "CREATE SCHEMA %s;\n", qnspname);
 
@@ -7953,7 +7963,9 @@ dumpExtension(Archive *fout, ExtensionInfo *extinfo)
 
 	qextname = pg_strdup(fmtId(extinfo->dobj.name));
 
-	appendPQExpBuffer(delq, "DROP EXTENSION %s;\n", qextname);
+	appendPQExpBuffer(delq, "DROP EXTENSION %s%s;\n",
+						    if_exists ? "IF EXISTS " : "",
+						    qextname);
 
 	if (!binary_upgrade)
 	{
@@ -8127,7 +8139,8 @@ dumpEnumType(Archive *fout, TypeInfo *tyinfo)
 	 * CASCADE shouldn't be required here as for normal types since the I/O
 	 * functions are generic and do not get dropped.
 	 */
-	appendPQExpBuffer(delq, "DROP TYPE %s.",
+	appendPQExpBuffer(delq, "DROP TYPE %s%s.",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tyinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, "%s;\n",
 					  qtypname);
@@ -8257,7 +8270,8 @@ dumpRangeType(Archive *fout, TypeInfo *tyinfo)
 	 * CASCADE shouldn't be required here as for normal types since the I/O
 	 * functions are generic and do not get dropped.
 	 */
-	appendPQExpBuffer(delq, "DROP TYPE %s.",
+	appendPQExpBuffer(delq, "DROP TYPE %s%s.",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tyinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, "%s;\n",
 					  qtypname);
@@ -8596,7 +8610,8 @@ dumpBaseType(Archive *fout, TypeInfo *tyinfo)
 	 * the type and its I/O functions makes it impossible to drop the type any
 	 * other way.
 	 */
-	appendPQExpBuffer(delq, "DROP TYPE %s.",
+	appendPQExpBuffer(delq, "DROP TYPE %s%s.",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tyinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, "%s CASCADE;\n",
 					  qtypname);
@@ -8855,7 +8870,8 @@ dumpDomain(Archive *fout, TypeInfo *tyinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP DOMAIN %s.",
+	appendPQExpBuffer(delq, "DROP DOMAIN %s%s.",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tyinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, "%s;\n",
 					  qtypname);
@@ -9069,7 +9085,8 @@ dumpCompositeType(Archive *fout, TypeInfo *tyinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP TYPE %s.",
+	appendPQExpBuffer(delq, "DROP TYPE %s%s.",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tyinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, "%s;\n",
 					  qtypname);
@@ -9379,7 +9396,8 @@ dumpProcLang(Archive *fout, ProcLangInfo *plang)
 	else
 		lanschema = NULL;
 
-	appendPQExpBuffer(delqry, "DROP PROCEDURAL LANGUAGE %s;\n",
+	appendPQExpBuffer(delqry, "DROP PROCEDURAL LANGUAGE %s%s;\n",
+					  if_exists ? "IF EXISTS " : "",
 					  qlanname);
 
 	if (useParams)
@@ -9923,7 +9941,8 @@ dumpFunc(Archive *fout, FuncInfo *finfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delqry, "DROP FUNCTION %s.%s;\n",
+	appendPQExpBuffer(delqry, "DROP FUNCTION %s%s.%s;\n",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(finfo->dobj.namespace->dobj.name),
 					  funcsig);
 
@@ -10141,7 +10160,8 @@ dumpCast(Archive *fout, CastInfo *cast)
 	delqry = createPQExpBuffer();
 	labelq = createPQExpBuffer();
 
-	appendPQExpBuffer(delqry, "DROP CAST (%s AS %s);\n",
+	appendPQExpBuffer(delqry, "DROP CAST %s(%s AS %s);\n",
+					if_exists ? "IF EXISTS " : "",
 					getFormattedTypeName(fout, cast->castsource, zeroAsNone),
 				   getFormattedTypeName(fout, cast->casttarget, zeroAsNone));
 
@@ -10411,7 +10431,8 @@ dumpOpr(Archive *fout, OprInfo *oprinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP OPERATOR %s.%s;\n",
+	appendPQExpBuffer(delq, "DROP OPERATOR %s%s.%s;\n",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(oprinfo->dobj.namespace->dobj.name),
 					  oprid->data);
 
@@ -10696,7 +10717,8 @@ dumpOpclass(Archive *fout, OpclassInfo *opcinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP OPERATOR CLASS %s",
+	appendPQExpBuffer(delq, "DROP OPERATOR CLASS %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(opcinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s",
 					  fmtId(opcinfo->dobj.name));
@@ -11140,7 +11162,8 @@ dumpOpfamily(Archive *fout, OpfamilyInfo *opfinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP OPERATOR FAMILY %s",
+	appendPQExpBuffer(delq, "DROP OPERATOR FAMILY %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(opfinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s",
 					  fmtId(opfinfo->dobj.name));
@@ -11314,7 +11337,8 @@ dumpCollation(Archive *fout, CollInfo *collinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP COLLATION %s",
+	appendPQExpBuffer(delq, "DROP COLLATION %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(collinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s;\n",
 					  fmtId(collinfo->dobj.name));
@@ -11411,7 +11435,8 @@ dumpConversion(Archive *fout, ConvInfo *convinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP CONVERSION %s",
+	appendPQExpBuffer(delq, "DROP CONVERSION %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(convinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s;\n",
 					  fmtId(convinfo->dobj.name));
@@ -11710,7 +11735,8 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP AGGREGATE %s.%s;\n",
+	appendPQExpBuffer(delq, "DROP AGGREGATE %s%s.%s;\n",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(agginfo->aggfn.dobj.namespace->dobj.name),
 					  aggsig);
 
@@ -11809,7 +11835,8 @@ dumpTSParser(Archive *fout, TSParserInfo *prsinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP TEXT SEARCH PARSER %s",
+	appendPQExpBuffer(delq, "DROP TEXT SEARCH PARSER %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(prsinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s;\n",
 					  fmtId(prsinfo->dobj.name));
@@ -11896,7 +11923,8 @@ dumpTSDictionary(Archive *fout, TSDictInfo *dictinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP TEXT SEARCH DICTIONARY %s",
+	appendPQExpBuffer(delq, "DROP TEXT SEARCH DICTIONARY %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(dictinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s;\n",
 					  fmtId(dictinfo->dobj.name));
@@ -11962,7 +11990,8 @@ dumpTSTemplate(Archive *fout, TSTemplateInfo *tmplinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP TEXT SEARCH TEMPLATE %s",
+	appendPQExpBuffer(delq, "DROP TEXT SEARCH TEMPLATE %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tmplinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s;\n",
 					  fmtId(tmplinfo->dobj.name));
@@ -12090,7 +12119,8 @@ dumpTSConfig(Archive *fout, TSConfigInfo *cfginfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP TEXT SEARCH CONFIGURATION %s",
+	appendPQExpBuffer(delq, "DROP TEXT SEARCH CONFIGURATION %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(cfginfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s;\n",
 					  fmtId(cfginfo->dobj.name));
@@ -12166,7 +12196,8 @@ dumpForeignDataWrapper(Archive *fout, FdwInfo *fdwinfo)
 
 	appendPQExpBufferStr(q, ";\n");
 
-	appendPQExpBuffer(delq, "DROP FOREIGN DATA WRAPPER %s;\n",
+	appendPQExpBuffer(delq, "DROP FOREIGN DATA WRAPPER %s%s;\n",
+					  if_exists ? "IF EXISTS " : "",
 					  qfdwname);
 
 	appendPQExpBuffer(labelq, "FOREIGN DATA WRAPPER %s",
@@ -12259,7 +12290,8 @@ dumpForeignServer(Archive *fout, ForeignServerInfo *srvinfo)
 
 	appendPQExpBufferStr(q, ";\n");
 
-	appendPQExpBuffer(delq, "DROP SERVER %s;\n",
+	appendPQExpBuffer(delq, "DROP SERVER %s%s;\n",
+					  if_exists ? "IF EXISTS " : "",
 					  qsrvname);
 
 	appendPQExpBuffer(labelq, "SERVER %s", qsrvname);
@@ -12377,7 +12409,9 @@ dumpUserMappings(Archive *fout,
 		appendPQExpBufferStr(q, ";\n");
 
 		resetPQExpBuffer(delq);
-		appendPQExpBuffer(delq, "DROP USER MAPPING FOR %s", fmtId(usename));
+		appendPQExpBuffer(delq, "DROP USER MAPPING %sFOR %s",
+							    if_exists ? "IF EXISTS " : "",
+							    fmtId(usename));
 		appendPQExpBuffer(delq, " SERVER %s;\n", fmtId(servername));
 
 		resetPQExpBuffer(tag);
@@ -12984,7 +13018,8 @@ dumpTableSchema(Archive *fout, TableInfo *tbinfo)
 		 * DROP must be fully qualified in case same name appears in
 		 * pg_catalog
 		 */
-		appendPQExpBuffer(delq, "DROP VIEW %s.",
+		appendPQExpBuffer(delq, "DROP VIEW %s%s.",
+						  if_exists ? "IF EXISTS " : "",
 						  fmtId(tbinfo->dobj.namespace->dobj.name));
 		appendPQExpBuffer(delq, "%s;\n",
 						  fmtId(tbinfo->dobj.name));
@@ -13061,7 +13096,8 @@ dumpTableSchema(Archive *fout, TableInfo *tbinfo)
 		 * DROP must be fully qualified in case same name appears in
 		 * pg_catalog
 		 */
-		appendPQExpBuffer(delq, "DROP %s %s.", reltypename,
+		appendPQExpBuffer(delq, "DROP %s %s%s.", reltypename,
+						  if_exists ? "IF EXISTS " : "",
 						  fmtId(tbinfo->dobj.namespace->dobj.name));
 		appendPQExpBuffer(delq, "%s;\n",
 						  fmtId(tbinfo->dobj.name));
@@ -13614,7 +13650,8 @@ dumpAttrDef(Archive *fout, AttrDefInfo *adinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "ALTER TABLE %s.",
+	appendPQExpBuffer(delq, "ALTER TABLE %s%s.",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tbinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, "%s ",
 					  fmtId(tbinfo->dobj.name));
@@ -13730,7 +13767,8 @@ dumpIndex(Archive *fout, IndxInfo *indxinfo)
 		 * DROP must be fully qualified in case same name appears in
 		 * pg_catalog
 		 */
-		appendPQExpBuffer(delq, "DROP INDEX %s.",
+		appendPQExpBuffer(delq, "DROP INDEX %s%s.",
+						  if_exists ? "IF EXISTS " : "",
 						  fmtId(tbinfo->dobj.namespace->dobj.name));
 		appendPQExpBuffer(delq, "%s;\n",
 						  fmtId(indxinfo->dobj.name));
@@ -13851,7 +13889,8 @@ dumpConstraint(Archive *fout, ConstraintInfo *coninfo)
 		 * DROP must be fully qualified in case same name appears in
 		 * pg_catalog
 		 */
-		appendPQExpBuffer(delq, "ALTER TABLE ONLY %s.",
+		appendPQExpBuffer(delq, "ALTER TABLE %sONLY %s.",
+						  if_exists ? "IF EXISTS " : "",
 						  fmtId(tbinfo->dobj.namespace->dobj.name));
 		appendPQExpBuffer(delq, "%s ",
 						  fmtId(tbinfo->dobj.name));
@@ -13884,7 +13923,8 @@ dumpConstraint(Archive *fout, ConstraintInfo *coninfo)
 		 * DROP must be fully qualified in case same name appears in
 		 * pg_catalog
 		 */
-		appendPQExpBuffer(delq, "ALTER TABLE ONLY %s.",
+		appendPQExpBuffer(delq, "ALTER TABLE %sONLY %s.",
+						  if_exists ? "IF EXISTS " : "",
 						  fmtId(tbinfo->dobj.namespace->dobj.name));
 		appendPQExpBuffer(delq, "%s ",
 						  fmtId(tbinfo->dobj.name));
@@ -14153,7 +14193,8 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delqry, "DROP SEQUENCE %s.",
+	appendPQExpBuffer(delqry, "DROP SEQUENCE %s%s.",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tbinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delqry, "%s;\n",
 					  fmtId(tbinfo->dobj.name));
@@ -14341,7 +14382,8 @@ dumpTrigger(Archive *fout, TriggerInfo *tginfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delqry, "DROP TRIGGER %s ",
+	appendPQExpBuffer(delqry, "DROP TRIGGER %s%s ",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tginfo->dobj.name));
 	appendPQExpBuffer(delqry, "ON %s.",
 					  fmtId(tbinfo->dobj.namespace->dobj.name));
@@ -14681,7 +14723,8 @@ dumpRule(Archive *fout, RuleInfo *rinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delcmd, "DROP RULE %s ",
+	appendPQExpBuffer(delcmd, "DROP RULE %s%s ",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(rinfo->dobj.name));
 	appendPQExpBuffer(delcmd, "ON %s.",
 					  fmtId(tbinfo->dobj.namespace->dobj.name));
diff --git a/src/bin/pg_dump/pg_dumpall.c b/src/bin/pg_dump/pg_dumpall.c
index 05c9646..b5bc693 100644
--- a/src/bin/pg_dump/pg_dumpall.c
+++ b/src/bin/pg_dump/pg_dumpall.c
@@ -71,6 +71,7 @@ static bool verbose = false;
 
 static int	binary_upgrade = 0;
 static int	column_inserts = 0;
+static int	if_exists = 0;
 static int	disable_dollar_quoting = 0;
 static int	disable_triggers = 0;
 static int	inserts = 0;
@@ -117,6 +118,7 @@ main(int argc, char *argv[])
 		{"attribute-inserts", no_argument, &column_inserts, 1},
 		{"binary-upgrade", no_argument, &binary_upgrade, 1},
 		{"column-inserts", no_argument, &column_inserts, 1},
+		{"if-exists", no_argument, &if_exists, 1},
 		{"disable-dollar-quoting", no_argument, &disable_dollar_quoting, 1},
 		{"disable-triggers", no_argument, &disable_triggers, 1},
 		{"inserts", no_argument, &inserts, 1},
@@ -348,6 +350,8 @@ main(int argc, char *argv[])
 		appendPQExpBufferStr(pgdumpopts, " --binary-upgrade");
 	if (column_inserts)
 		appendPQExpBufferStr(pgdumpopts, " --column-inserts");
+	if (if_exists)
+		appendPQExpBufferStr(pgdumpopts, " --if-exists");
 	if (disable_dollar_quoting)
 		appendPQExpBufferStr(pgdumpopts, " --disable-dollar-quoting");
 	if (disable_triggers)
@@ -562,6 +566,7 @@ help(void)
 	printf(_("  -x, --no-privileges          do not dump privileges (grant/revoke)\n"));
 	printf(_("  --binary-upgrade             for use by upgrade utilities only\n"));
 	printf(_("  --column-inserts             dump data as INSERT commands with column names\n"));
+	printf(_("  --if-exists                  don't report error if cleaned object doesn't exist\n"));
 	printf(_("  --disable-dollar-quoting     disable dollar quoting, use SQL standard quoting\n"));
 	printf(_("  --disable-triggers           disable triggers during data-only restore\n"));
 	printf(_("  --inserts                    dump data as INSERT commands, rather than COPY\n"));
diff --git a/src/bin/pg_dump/pg_restore.c b/src/bin/pg_dump/pg_restore.c
index 2648003..74f9c2a 100644
--- a/src/bin/pg_dump/pg_restore.c
+++ b/src/bin/pg_dump/pg_restore.c
@@ -76,6 +76,7 @@ main(int argc, char **argv)
 	Archive    *AH;
 	char	   *inputFileSpec;
 	static int	disable_triggers = 0;
+	static int	if_exists = 0;
 	static int	no_data_for_failed_tables = 0;
 	static int	outputNoTablespaces = 0;
 	static int	use_setsessauth = 0;
@@ -116,6 +117,7 @@ main(int argc, char **argv)
 		 * the following options don't have an equivalent short option letter
 		 */
 		{"disable-triggers", no_argument, &disable_triggers, 1},
+		{"if-exists", no_argument, &if_exists, 1},
 		{"no-data-for-failed-tables", no_argument, &no_data_for_failed_tables, 1},
 		{"no-tablespaces", no_argument, &outputNoTablespaces, 1},
 		{"role", required_argument, NULL, 2},
@@ -342,6 +344,14 @@ main(int argc, char **argv)
 	opts->use_setsessauth = use_setsessauth;
 	opts->no_security_labels = no_security_labels;
 
+	if (if_exists && !opts->dropSchema)
+	{
+		fprintf(stderr, _("%s: option --if-exists requires -c/--clean option\n"),
+				progname);
+		exit_nicely(1);
+	}
+	opts->if_exists = if_exists;
+
 	if (opts->formatName)
 	{
 		switch (opts->formatName[0])
@@ -456,6 +466,7 @@ usage(const char *progname)
 	printf(_("  -x, --no-privileges          skip restoration of access privileges (grant/revoke)\n"));
 	printf(_("  -1, --single-transaction     restore as a single transaction\n"));
 	printf(_("  --disable-triggers           disable triggers during data-only restore\n"));
+	printf(_("  --if-exists                  use IF EXISTS when dropping objects\n"));
 	printf(_("  --no-data-for-failed-tables  do not restore data of tables that could not be\n"
 			 "                               created\n"));
 	printf(_("  --no-security-labels         do not restore security labels\n"));

commit 3fecb7805261e96db764fffcae2bb912538903f5
Author: Pavel Stehule <pavel.stehule@gmail.com>
Date:   Fri Jan 17 13:37:51 2014 +0100

    review related fixes

diff --git a/doc/src/sgml/ref/pg_dump.sgml b/doc/src/sgml/ref/pg_dump.sgml
index 8d45f24..c39767b 100644
--- a/doc/src/sgml/ref/pg_dump.sgml
+++ b/doc/src/sgml/ref/pg_dump.sgml
@@ -650,6 +650,16 @@ PostgreSQL documentation
      </varlistentry>
 
      <varlistentry>
+      <term><option>--if-exists</option></term>
+      <listitem>
+       <para>
+        It uses conditional commands (with <literal>IF EXISTS</literal>
+        clause) for cleaning database schema.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><option>--disable-dollar-quoting</></term>
       <listitem>
        <para>
diff --git a/doc/src/sgml/ref/pg_dumpall.sgml b/doc/src/sgml/ref/pg_dumpall.sgml
index 5c6a101..ba6583d 100644
--- a/doc/src/sgml/ref/pg_dumpall.sgml
+++ b/doc/src/sgml/ref/pg_dumpall.sgml
@@ -301,6 +301,16 @@ PostgreSQL documentation
      </varlistentry>
 
      <varlistentry>
+      <term><option>--if-exists</option></term>
+      <listitem>
+       <para>
+        It uses conditional commands (with <literal>IF EXISTS</literal>
+        clause) for cleaning database schema.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><option>--inserts</option></term>
       <listitem>
        <para>
diff --git a/doc/src/sgml/ref/pg_restore.sgml b/doc/src/sgml/ref/pg_restore.sgml
index 717da42..55326d5 100644
--- a/doc/src/sgml/ref/pg_restore.sgml
+++ b/doc/src/sgml/ref/pg_restore.sgml
@@ -490,6 +490,16 @@
      </varlistentry>
 
      <varlistentry>
+      <term><option>--if-exists</option></term>
+      <listitem>
+       <para>
+        It uses conditional commands (with <literal>IF EXISTS</literal>
+        clause) for cleaning database schema.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><option>--no-data-for-failed-tables</option></term>
       <listitem>
        <para>
diff --git a/src/bin/pg_dump/pg_backup.h b/src/bin/pg_dump/pg_backup.h
index 6927968..83f7216 100644
--- a/src/bin/pg_dump/pg_backup.h
+++ b/src/bin/pg_dump/pg_backup.h
@@ -113,6 +113,7 @@ typedef struct _restoreOptions
 	char	   *superuser;		/* Username to use as superuser */
 	char	   *use_role;		/* Issue SET ROLE to this */
 	int			dropSchema;
+	int			if_exists;
 	const char *filename;
 	int			dataOnly;
 	int			schemaOnly;
diff --git a/src/bin/pg_dump/pg_backup_archiver.c b/src/bin/pg_dump/pg_backup_archiver.c
index 7fc0288..0677712 100644
--- a/src/bin/pg_dump/pg_backup_archiver.c
+++ b/src/bin/pg_dump/pg_backup_archiver.c
@@ -413,8 +413,30 @@ RestoreArchive(Archive *AHX)
 				/* Select owner and schema as necessary */
 				_becomeOwner(AH, te);
 				_selectOutputSchema(AH, te->namespace);
-				/* Drop it */
-				ahprintf(AH, "%s", te->dropStmt);
+
+				if (*te->dropStmt != '\0')
+				{
+					/* Inject IF EXISTS clause when it is required. */
+					if (ropt->if_exists)
+					{
+						char buffer[40];
+						size_t l;
+
+						/* But do it only, when it is not there yet. */
+						snprintf(buffer, sizeof(buffer), "DROP %s IF EXISTS",
+												 te->desc);
+						l = strlen(buffer);
+
+						if (strncmp(te->dropStmt, buffer, l) != 0)
+						{
+							ahprintf(AH, "DROP %s IF EXISTS %s",
+											te->desc,
+											te->dropStmt + l);
+						}
+						else
+							ahprintf(AH, "%s", te->dropStmt);
+					}
+				}
 			}
 		}
 
@@ -2942,9 +2964,39 @@ _getObjectDescription(PQExpBuffer buf, TocEntry *te, ArchiveHandle *AH)
 		strcmp(type, "OPERATOR CLASS") == 0 ||
 		strcmp(type, "OPERATOR FAMILY") == 0)
 	{
-		/* Chop "DROP " off the front and make a modifiable copy */
-		char	   *first = pg_strdup(te->dropStmt + 5);
-		char	   *last;
+		char	    *first;
+		char	    *last;
+
+		/*
+		 * Object description is based on dropStmt statement. But
+		 * a drop statements can be enhanced about IF EXISTS clause.
+		 * We have to increase a offset in this case, "IF EXISTS"
+		 * should not be included on object description.
+		 */
+		if (strstr(te->dropStmt, "IF EXISTS") != NULL)
+		{
+			char buffer[40];
+			size_t   l;
+
+			/* IF EXISTS clause should be optional, check it*/
+			snprintf(buffer, sizeof(buffer), "DROP %s IF EXISTS", type);
+			l = strlen(buffer);
+
+			if (strncmp(te->dropStmt, buffer, l) == 0)
+			{
+				/* append command type to target type */
+				appendPQExpBufferStr(buf, type);
+
+				/* skip first n chars, and create a modifieble copy */
+				first = pg_strdup(te->dropStmt + l);
+			}
+			else
+				/* DROP IF EXISTS pattern is not appliable on dropStmt */
+				first = pg_strdup(te->dropStmt + 5);
+		}
+		else
+			/* IF EXISTS clause was not used, simple solution */
+			first = pg_strdup(te->dropStmt + 5);
 
 		/* point to last character in string */
 		last = first + strlen(first) - 1;
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 3862f05..1227d55 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -136,6 +136,7 @@ static int	binary_upgrade = 0;
 static int	disable_dollar_quoting = 0;
 static int	dump_inserts = 0;
 static int	column_inserts = 0;
+static int	if_exists = 0;
 static int	no_security_labels = 0;
 static int	no_synchronized_snapshots = 0;
 static int	no_unlogged_table_data = 0;
@@ -349,6 +350,7 @@ main(int argc, char **argv)
 		{"disable-dollar-quoting", no_argument, &disable_dollar_quoting, 1},
 		{"disable-triggers", no_argument, &disable_triggers, 1},
 		{"exclude-table-data", required_argument, NULL, 4},
+		{"if-exists", no_argument, &if_exists, 1},
 		{"inserts", no_argument, &dump_inserts, 1},
 		{"lock-wait-timeout", required_argument, NULL, 2},
 		{"no-tablespaces", no_argument, &outputNoTablespaces, 1},
@@ -577,6 +579,9 @@ main(int argc, char **argv)
 		exit_nicely(1);
 	}
 
+	if (if_exists && !outputClean)
+		exit_horribly(NULL, "option --if-exists requires -c/--clean option\n");
+
 	/* Identify archive format to emit */
 	archiveFormat = parseArchiveFormat(format, &archiveMode);
 
@@ -809,6 +814,7 @@ main(int argc, char **argv)
 	ropt->dropSchema = outputClean;
 	ropt->dataOnly = dataOnly;
 	ropt->schemaOnly = schemaOnly;
+	ropt->if_exists = if_exists;
 	ropt->dumpSections = dumpSections;
 	ropt->aclsSkip = aclsSkip;
 	ropt->superuser = outputSuperuser;
@@ -890,6 +896,7 @@ help(const char *progname)
 	printf(_("  --disable-dollar-quoting     disable dollar quoting, use SQL standard quoting\n"));
 	printf(_("  --disable-triggers           disable triggers during data-only restore\n"));
 	printf(_("  --exclude-table-data=TABLE   do NOT dump data for the named table(s)\n"));
+	printf(_("  --if-exists                  use IF EXISTS when dropping objects\n"));
 	printf(_("  --inserts                    dump data as INSERT commands, rather than COPY\n"));
 	printf(_("  --no-security-labels         do not dump security label assignments\n"));
 	printf(_("  --no-synchronized-snapshots  do not use synchronized snapshots in parallel jobs\n"));
@@ -2290,7 +2297,8 @@ dumpDatabase(Archive *fout)
 
 	}
 
-	appendPQExpBuffer(delQry, "DROP DATABASE %s;\n",
+	appendPQExpBuffer(delQry, "DROP DATABASE %s%s;\n",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(datname));
 
 	dbDumpId = createDumpId();
@@ -7894,7 +7902,9 @@ dumpNamespace(Archive *fout, NamespaceInfo *nspinfo)
 
 	qnspname = pg_strdup(fmtId(nspinfo->dobj.name));
 
-	appendPQExpBuffer(delq, "DROP SCHEMA %s;\n", qnspname);
+	appendPQExpBuffer(delq, "DROP SCHEMA %s%s;\n",
+						    if_exists ? "IF EXISTS " : "",
+						    qnspname);
 
 	appendPQExpBuffer(q, "CREATE SCHEMA %s;\n", qnspname);
 
@@ -7953,7 +7963,9 @@ dumpExtension(Archive *fout, ExtensionInfo *extinfo)
 
 	qextname = pg_strdup(fmtId(extinfo->dobj.name));
 
-	appendPQExpBuffer(delq, "DROP EXTENSION %s;\n", qextname);
+	appendPQExpBuffer(delq, "DROP EXTENSION %s%s;\n",
+						    if_exists ? "IF EXISTS " : "",
+						    qextname);
 
 	if (!binary_upgrade)
 	{
@@ -8127,7 +8139,8 @@ dumpEnumType(Archive *fout, TypeInfo *tyinfo)
 	 * CASCADE shouldn't be required here as for normal types since the I/O
 	 * functions are generic and do not get dropped.
 	 */
-	appendPQExpBuffer(delq, "DROP TYPE %s.",
+	appendPQExpBuffer(delq, "DROP TYPE %s%s.",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tyinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, "%s;\n",
 					  qtypname);
@@ -8257,7 +8270,8 @@ dumpRangeType(Archive *fout, TypeInfo *tyinfo)
 	 * CASCADE shouldn't be required here as for normal types since the I/O
 	 * functions are generic and do not get dropped.
 	 */
-	appendPQExpBuffer(delq, "DROP TYPE %s.",
+	appendPQExpBuffer(delq, "DROP TYPE %s%s.",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tyinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, "%s;\n",
 					  qtypname);
@@ -8596,7 +8610,8 @@ dumpBaseType(Archive *fout, TypeInfo *tyinfo)
 	 * the type and its I/O functions makes it impossible to drop the type any
 	 * other way.
 	 */
-	appendPQExpBuffer(delq, "DROP TYPE %s.",
+	appendPQExpBuffer(delq, "DROP TYPE %s%s.",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tyinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, "%s CASCADE;\n",
 					  qtypname);
@@ -8855,7 +8870,8 @@ dumpDomain(Archive *fout, TypeInfo *tyinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP DOMAIN %s.",
+	appendPQExpBuffer(delq, "DROP DOMAIN %s%s.",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tyinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, "%s;\n",
 					  qtypname);
@@ -9069,7 +9085,8 @@ dumpCompositeType(Archive *fout, TypeInfo *tyinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP TYPE %s.",
+	appendPQExpBuffer(delq, "DROP TYPE %s%s.",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tyinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, "%s;\n",
 					  qtypname);
@@ -9379,7 +9396,8 @@ dumpProcLang(Archive *fout, ProcLangInfo *plang)
 	else
 		lanschema = NULL;
 
-	appendPQExpBuffer(delqry, "DROP PROCEDURAL LANGUAGE %s;\n",
+	appendPQExpBuffer(delqry, "DROP PROCEDURAL LANGUAGE %s%s;\n",
+					  if_exists ? "IF EXISTS " : "",
 					  qlanname);
 
 	if (useParams)
@@ -9923,7 +9941,8 @@ dumpFunc(Archive *fout, FuncInfo *finfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delqry, "DROP FUNCTION %s.%s;\n",
+	appendPQExpBuffer(delqry, "DROP FUNCTION %s%s.%s;\n",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(finfo->dobj.namespace->dobj.name),
 					  funcsig);
 
@@ -10141,7 +10160,8 @@ dumpCast(Archive *fout, CastInfo *cast)
 	delqry = createPQExpBuffer();
 	labelq = createPQExpBuffer();
 
-	appendPQExpBuffer(delqry, "DROP CAST (%s AS %s);\n",
+	appendPQExpBuffer(delqry, "DROP CAST %s(%s AS %s);\n",
+					if_exists ? "IF EXISTS " : "",
 					getFormattedTypeName(fout, cast->castsource, zeroAsNone),
 				   getFormattedTypeName(fout, cast->casttarget, zeroAsNone));
 
@@ -10411,7 +10431,8 @@ dumpOpr(Archive *fout, OprInfo *oprinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP OPERATOR %s.%s;\n",
+	appendPQExpBuffer(delq, "DROP OPERATOR %s%s.%s;\n",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(oprinfo->dobj.namespace->dobj.name),
 					  oprid->data);
 
@@ -10696,7 +10717,8 @@ dumpOpclass(Archive *fout, OpclassInfo *opcinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP OPERATOR CLASS %s",
+	appendPQExpBuffer(delq, "DROP OPERATOR CLASS %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(opcinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s",
 					  fmtId(opcinfo->dobj.name));
@@ -11140,7 +11162,8 @@ dumpOpfamily(Archive *fout, OpfamilyInfo *opfinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP OPERATOR FAMILY %s",
+	appendPQExpBuffer(delq, "DROP OPERATOR FAMILY %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(opfinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s",
 					  fmtId(opfinfo->dobj.name));
@@ -11314,7 +11337,8 @@ dumpCollation(Archive *fout, CollInfo *collinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP COLLATION %s",
+	appendPQExpBuffer(delq, "DROP COLLATION %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(collinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s;\n",
 					  fmtId(collinfo->dobj.name));
@@ -11411,7 +11435,8 @@ dumpConversion(Archive *fout, ConvInfo *convinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP CONVERSION %s",
+	appendPQExpBuffer(delq, "DROP CONVERSION %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(convinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s;\n",
 					  fmtId(convinfo->dobj.name));
@@ -11723,7 +11748,8 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP AGGREGATE %s.%s;\n",
+	appendPQExpBuffer(delq, "DROP AGGREGATE %s%s.%s;\n",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(agginfo->aggfn.dobj.namespace->dobj.name),
 					  aggsig);
 
@@ -11822,7 +11848,8 @@ dumpTSParser(Archive *fout, TSParserInfo *prsinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP TEXT SEARCH PARSER %s",
+	appendPQExpBuffer(delq, "DROP TEXT SEARCH PARSER %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(prsinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s;\n",
 					  fmtId(prsinfo->dobj.name));
@@ -11909,7 +11936,8 @@ dumpTSDictionary(Archive *fout, TSDictInfo *dictinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP TEXT SEARCH DICTIONARY %s",
+	appendPQExpBuffer(delq, "DROP TEXT SEARCH DICTIONARY %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(dictinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s;\n",
 					  fmtId(dictinfo->dobj.name));
@@ -11975,7 +12003,8 @@ dumpTSTemplate(Archive *fout, TSTemplateInfo *tmplinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP TEXT SEARCH TEMPLATE %s",
+	appendPQExpBuffer(delq, "DROP TEXT SEARCH TEMPLATE %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tmplinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s;\n",
 					  fmtId(tmplinfo->dobj.name));
@@ -12103,7 +12132,8 @@ dumpTSConfig(Archive *fout, TSConfigInfo *cfginfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP TEXT SEARCH CONFIGURATION %s",
+	appendPQExpBuffer(delq, "DROP TEXT SEARCH CONFIGURATION %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(cfginfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s;\n",
 					  fmtId(cfginfo->dobj.name));
@@ -12179,7 +12209,8 @@ dumpForeignDataWrapper(Archive *fout, FdwInfo *fdwinfo)
 
 	appendPQExpBufferStr(q, ";\n");
 
-	appendPQExpBuffer(delq, "DROP FOREIGN DATA WRAPPER %s;\n",
+	appendPQExpBuffer(delq, "DROP FOREIGN DATA WRAPPER %s%s;\n",
+					  if_exists ? "IF EXISTS " : "",
 					  qfdwname);
 
 	appendPQExpBuffer(labelq, "FOREIGN DATA WRAPPER %s",
@@ -12272,7 +12303,8 @@ dumpForeignServer(Archive *fout, ForeignServerInfo *srvinfo)
 
 	appendPQExpBufferStr(q, ";\n");
 
-	appendPQExpBuffer(delq, "DROP SERVER %s;\n",
+	appendPQExpBuffer(delq, "DROP SERVER %s%s;\n",
+					  if_exists ? "IF EXISTS " : "",
 					  qsrvname);
 
 	appendPQExpBuffer(labelq, "SERVER %s", qsrvname);
@@ -12390,7 +12422,9 @@ dumpUserMappings(Archive *fout,
 		appendPQExpBufferStr(q, ";\n");
 
 		resetPQExpBuffer(delq);
-		appendPQExpBuffer(delq, "DROP USER MAPPING FOR %s", fmtId(usename));
+		appendPQExpBuffer(delq, "DROP USER MAPPING %sFOR %s",
+							    if_exists ? "IF EXISTS " : "",
+							    fmtId(usename));
 		appendPQExpBuffer(delq, " SERVER %s;\n", fmtId(servername));
 
 		resetPQExpBuffer(tag);
@@ -12997,7 +13031,8 @@ dumpTableSchema(Archive *fout, TableInfo *tbinfo)
 		 * DROP must be fully qualified in case same name appears in
 		 * pg_catalog
 		 */
-		appendPQExpBuffer(delq, "DROP VIEW %s.",
+		appendPQExpBuffer(delq, "DROP VIEW %s%s.",
+						  if_exists ? "IF EXISTS " : "",
 						  fmtId(tbinfo->dobj.namespace->dobj.name));
 		appendPQExpBuffer(delq, "%s;\n",
 						  fmtId(tbinfo->dobj.name));
@@ -13074,7 +13109,8 @@ dumpTableSchema(Archive *fout, TableInfo *tbinfo)
 		 * DROP must be fully qualified in case same name appears in
 		 * pg_catalog
 		 */
-		appendPQExpBuffer(delq, "DROP %s %s.", reltypename,
+		appendPQExpBuffer(delq, "DROP %s %s%s.", reltypename,
+						  if_exists ? "IF EXISTS " : "",
 						  fmtId(tbinfo->dobj.namespace->dobj.name));
 		appendPQExpBuffer(delq, "%s;\n",
 						  fmtId(tbinfo->dobj.name));
@@ -13627,7 +13663,8 @@ dumpAttrDef(Archive *fout, AttrDefInfo *adinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "ALTER TABLE %s.",
+	appendPQExpBuffer(delq, "ALTER TABLE %s%s.",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tbinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, "%s ",
 					  fmtId(tbinfo->dobj.name));
@@ -13743,7 +13780,8 @@ dumpIndex(Archive *fout, IndxInfo *indxinfo)
 		 * DROP must be fully qualified in case same name appears in
 		 * pg_catalog
 		 */
-		appendPQExpBuffer(delq, "DROP INDEX %s.",
+		appendPQExpBuffer(delq, "DROP INDEX %s%s.",
+						  if_exists ? "IF EXISTS " : "",
 						  fmtId(tbinfo->dobj.namespace->dobj.name));
 		appendPQExpBuffer(delq, "%s;\n",
 						  fmtId(indxinfo->dobj.name));
@@ -13864,7 +13902,8 @@ dumpConstraint(Archive *fout, ConstraintInfo *coninfo)
 		 * DROP must be fully qualified in case same name appears in
 		 * pg_catalog
 		 */
-		appendPQExpBuffer(delq, "ALTER TABLE ONLY %s.",
+		appendPQExpBuffer(delq, "ALTER TABLE %sONLY %s.",
+						  if_exists ? "IF EXISTS " : "",
 						  fmtId(tbinfo->dobj.namespace->dobj.name));
 		appendPQExpBuffer(delq, "%s ",
 						  fmtId(tbinfo->dobj.name));
@@ -13897,7 +13936,8 @@ dumpConstraint(Archive *fout, ConstraintInfo *coninfo)
 		 * DROP must be fully qualified in case same name appears in
 		 * pg_catalog
 		 */
-		appendPQExpBuffer(delq, "ALTER TABLE ONLY %s.",
+		appendPQExpBuffer(delq, "ALTER TABLE %sONLY %s.",
+						  if_exists ? "IF EXISTS " : "",
 						  fmtId(tbinfo->dobj.namespace->dobj.name));
 		appendPQExpBuffer(delq, "%s ",
 						  fmtId(tbinfo->dobj.name));
@@ -14166,7 +14206,8 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delqry, "DROP SEQUENCE %s.",
+	appendPQExpBuffer(delqry, "DROP SEQUENCE %s%s.",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tbinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delqry, "%s;\n",
 					  fmtId(tbinfo->dobj.name));
@@ -14362,7 +14403,8 @@ dumpTrigger(Archive *fout, TriggerInfo *tginfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delqry, "DROP TRIGGER %s ",
+	appendPQExpBuffer(delqry, "DROP TRIGGER %s%s ",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tginfo->dobj.name));
 	appendPQExpBuffer(delqry, "ON %s.",
 					  fmtId(tbinfo->dobj.namespace->dobj.name));
@@ -14710,7 +14752,8 @@ dumpRule(Archive *fout, RuleInfo *rinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delcmd, "DROP RULE %s ",
+	appendPQExpBuffer(delcmd, "DROP RULE %s%s ",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(rinfo->dobj.name));
 	appendPQExpBuffer(delcmd, "ON %s.",
 					  fmtId(tbinfo->dobj.namespace->dobj.name));
diff --git a/src/bin/pg_dump/pg_dumpall.c b/src/bin/pg_dump/pg_dumpall.c
index 193c1a0..e54a829 100644
--- a/src/bin/pg_dump/pg_dumpall.c
+++ b/src/bin/pg_dump/pg_dumpall.c
@@ -73,6 +73,7 @@ static int	binary_upgrade = 0;
 static int	column_inserts = 0;
 static int	disable_dollar_quoting = 0;
 static int	disable_triggers = 0;
+static int	if_exists = 0;
 static int	inserts = 0;
 static int	no_tablespaces = 0;
 static int	use_setsessauth = 0;
@@ -119,6 +120,7 @@ main(int argc, char *argv[])
 		{"column-inserts", no_argument, &column_inserts, 1},
 		{"disable-dollar-quoting", no_argument, &disable_dollar_quoting, 1},
 		{"disable-triggers", no_argument, &disable_triggers, 1},
+		{"if-exists", no_argument, &if_exists, 1},
 		{"inserts", no_argument, &inserts, 1},
 		{"lock-wait-timeout", required_argument, NULL, 2},
 		{"no-tablespaces", no_argument, &no_tablespaces, 1},
@@ -348,6 +350,8 @@ main(int argc, char *argv[])
 		appendPQExpBufferStr(pgdumpopts, " --binary-upgrade");
 	if (column_inserts)
 		appendPQExpBufferStr(pgdumpopts, " --column-inserts");
+	if (if_exists)
+		appendPQExpBufferStr(pgdumpopts, " --if-exists");
 	if (disable_dollar_quoting)
 		appendPQExpBufferStr(pgdumpopts, " --disable-dollar-quoting");
 	if (disable_triggers)
@@ -564,6 +568,7 @@ help(void)
 	printf(_("  --column-inserts             dump data as INSERT commands with column names\n"));
 	printf(_("  --disable-dollar-quoting     disable dollar quoting, use SQL standard quoting\n"));
 	printf(_("  --disable-triggers           disable triggers during data-only restore\n"));
+	printf(_("  --if-exists                  use IF EXISTS when dropping objects\n"));
 	printf(_("  --inserts                    dump data as INSERT commands, rather than COPY\n"));
 	printf(_("  --no-security-labels         do not dump security label assignments\n"));
 	printf(_("  --no-tablespaces             do not dump tablespace assignments\n"));
diff --git a/src/bin/pg_dump/pg_restore.c b/src/bin/pg_dump/pg_restore.c
index 2648003..74f9c2a 100644
--- a/src/bin/pg_dump/pg_restore.c
+++ b/src/bin/pg_dump/pg_restore.c
@@ -76,6 +76,7 @@ main(int argc, char **argv)
 	Archive    *AH;
 	char	   *inputFileSpec;
 	static int	disable_triggers = 0;
+	static int	if_exists = 0;
 	static int	no_data_for_failed_tables = 0;
 	static int	outputNoTablespaces = 0;
 	static int	use_setsessauth = 0;
@@ -116,6 +117,7 @@ main(int argc, char **argv)
 		 * the following options don't have an equivalent short option letter
 		 */
 		{"disable-triggers", no_argument, &disable_triggers, 1},
+		{"if-exists", no_argument, &if_exists, 1},
 		{"no-data-for-failed-tables", no_argument, &no_data_for_failed_tables, 1},
 		{"no-tablespaces", no_argument, &outputNoTablespaces, 1},
 		{"role", required_argument, NULL, 2},
@@ -342,6 +344,14 @@ main(int argc, char **argv)
 	opts->use_setsessauth = use_setsessauth;
 	opts->no_security_labels = no_security_labels;
 
+	if (if_exists && !opts->dropSchema)
+	{
+		fprintf(stderr, _("%s: option --if-exists requires -c/--clean option\n"),
+				progname);
+		exit_nicely(1);
+	}
+	opts->if_exists = if_exists;
+
 	if (opts->formatName)
 	{
 		switch (opts->formatName[0])
@@ -456,6 +466,7 @@ usage(const char *progname)
 	printf(_("  -x, --no-privileges          skip restoration of access privileges (grant/revoke)\n"));
 	printf(_("  -1, --single-transaction     restore as a single transaction\n"));
 	printf(_("  --disable-triggers           disable triggers during data-only restore\n"));
+	printf(_("  --if-exists                  use IF EXISTS when dropping objects\n"));
 	printf(_("  --no-data-for-failed-tables  do not restore data of tables that could not be\n"
 			 "                               created\n"));
 	printf(_("  --no-security-labels         do not restore security labels\n"));

commit 0ad2dda3d5efe77cd0cbec9905bfe3fc36f084e1
Author: Pavel Stehule <pavel.stehule@gooddata.com>
Date:   Sat Jan 25 13:38:22 2014 +0100

    fixes related to review

diff --git a/doc/src/sgml/ref/pg_dump.sgml b/doc/src/sgml/ref/pg_dump.sgml
index 8d45f24..c39767b 100644
--- a/doc/src/sgml/ref/pg_dump.sgml
+++ b/doc/src/sgml/ref/pg_dump.sgml
@@ -650,6 +650,16 @@ PostgreSQL documentation
      </varlistentry>
 
      <varlistentry>
+      <term><option>--if-exists</option></term>
+      <listitem>
+       <para>
+        It uses conditional commands (with <literal>IF EXISTS</literal>
+        clause) for cleaning database schema.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><option>--disable-dollar-quoting</></term>
       <listitem>
        <para>
diff --git a/doc/src/sgml/ref/pg_dumpall.sgml b/doc/src/sgml/ref/pg_dumpall.sgml
index 5c6a101..ba6583d 100644
--- a/doc/src/sgml/ref/pg_dumpall.sgml
+++ b/doc/src/sgml/ref/pg_dumpall.sgml
@@ -301,6 +301,16 @@ PostgreSQL documentation
      </varlistentry>
 
      <varlistentry>
+      <term><option>--if-exists</option></term>
+      <listitem>
+       <para>
+        It uses conditional commands (with <literal>IF EXISTS</literal>
+        clause) for cleaning database schema.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><option>--inserts</option></term>
       <listitem>
        <para>
diff --git a/doc/src/sgml/ref/pg_restore.sgml b/doc/src/sgml/ref/pg_restore.sgml
index 717da42..55326d5 100644
--- a/doc/src/sgml/ref/pg_restore.sgml
+++ b/doc/src/sgml/ref/pg_restore.sgml
@@ -490,6 +490,16 @@
      </varlistentry>
 
      <varlistentry>
+      <term><option>--if-exists</option></term>
+      <listitem>
+       <para>
+        It uses conditional commands (with <literal>IF EXISTS</literal>
+        clause) for cleaning database schema.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><option>--no-data-for-failed-tables</option></term>
       <listitem>
        <para>
diff --git a/src/bin/pg_dump/pg_backup.h b/src/bin/pg_dump/pg_backup.h
index 6927968..83f7216 100644
--- a/src/bin/pg_dump/pg_backup.h
+++ b/src/bin/pg_dump/pg_backup.h
@@ -113,6 +113,7 @@ typedef struct _restoreOptions
 	char	   *superuser;		/* Username to use as superuser */
 	char	   *use_role;		/* Issue SET ROLE to this */
 	int			dropSchema;
+	int			if_exists;
 	const char *filename;
 	int			dataOnly;
 	int			schemaOnly;
diff --git a/src/bin/pg_dump/pg_backup_archiver.c b/src/bin/pg_dump/pg_backup_archiver.c
index 7fc0288..46d2b61 100644
--- a/src/bin/pg_dump/pg_backup_archiver.c
+++ b/src/bin/pg_dump/pg_backup_archiver.c
@@ -413,8 +413,59 @@ RestoreArchive(Archive *AHX)
 				/* Select owner and schema as necessary */
 				_becomeOwner(AH, te);
 				_selectOutputSchema(AH, te->namespace);
-				/* Drop it */
-				ahprintf(AH, "%s", te->dropStmt);
+
+				if (*te->dropStmt != '\0')
+				{
+					/* Inject IF EXISTS clause to DROP part when it is required. */
+					if (ropt->if_exists)
+					{
+						char buffer[40];
+						char *mark;
+
+						/*
+						 * Descriptor string should not be same as object
+						 * specifier for DROP STATEMENT.
+						 */
+						if (strcmp(te->desc, "DEFAULT") == 0)
+						{
+							mark = NULL;
+						}
+						else
+						{
+							if (strcmp(te->desc, "CONSTRAINT") == 0 ||
+									 strcmp(te->desc, "CHECK CONSTRAINT") == 0 ||
+									 strcmp(te->desc, "FK CONSTRAINT") == 0)
+								strcpy(buffer, "DROP CONSTRAINT");
+							else
+								snprintf(buffer, sizeof(buffer), "DROP %s",
+													 te->desc);
+
+							mark = strstr(te->dropStmt, buffer);
+						}
+
+						if (mark != NULL)
+						{
+							size_t l = strlen(buffer);
+
+							/*
+							 * Insert IF EXISTS clause when it is not
+							 * used yet.
+							 */
+							if (strncmp(mark + l, " IF EXISTS", 10) != 0)
+							{
+								*mark = '\0';
+
+								ahprintf(AH, "%s", te->dropStmt);
+								ahprintf(AH, "%s IF EXISTS", buffer);
+								ahprintf(AH, "%s", mark + l);
+							}
+							else
+								ahprintf(AH, "%s", te->dropStmt);
+						}
+						else
+							ahprintf(AH, "%s", te->dropStmt);
+					}
+				}
 			}
 		}
 
@@ -2942,9 +2993,38 @@ _getObjectDescription(PQExpBuffer buf, TocEntry *te, ArchiveHandle *AH)
 		strcmp(type, "OPERATOR CLASS") == 0 ||
 		strcmp(type, "OPERATOR FAMILY") == 0)
 	{
-		/* Chop "DROP " off the front and make a modifiable copy */
-		char	   *first = pg_strdup(te->dropStmt + 5);
-		char	   *last;
+		char	    *first;
+		char	    *last;
+
+		/*
+		 * Object description is based on dropStmt statement which may have
+		 * IF EXISTS clause.  Thus we need to update an offset such that it
+		 * won't be included in the object description.
+		 */
+		if (strstr(te->dropStmt, "IF EXISTS") != NULL)
+		{
+			char buffer[40];
+			size_t   l;
+
+			/* IF EXISTS clause should be optional, check it*/
+			snprintf(buffer, sizeof(buffer), "DROP %s IF EXISTS", type);
+			l = strlen(buffer);
+
+			if (strncmp(te->dropStmt, buffer, l) == 0)
+			{
+				/* append command type to target type */
+				appendPQExpBufferStr(buf, type);
+
+				/* skip first n chars, and create a modifiable copy */
+				first = pg_strdup(te->dropStmt + l);
+			}
+			else
+				/* DROP IF EXISTS pattern is not applicable on dropStmt */
+				first = pg_strdup(te->dropStmt + 5);
+		}
+		else
+			/* IF EXISTS clause was not used, simple solution */
+			first = pg_strdup(te->dropStmt + 5);
 
 		/* point to last character in string */
 		last = first + strlen(first) - 1;
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 3862f05..1227d55 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -136,6 +136,7 @@ static int	binary_upgrade = 0;
 static int	disable_dollar_quoting = 0;
 static int	dump_inserts = 0;
 static int	column_inserts = 0;
+static int	if_exists = 0;
 static int	no_security_labels = 0;
 static int	no_synchronized_snapshots = 0;
 static int	no_unlogged_table_data = 0;
@@ -349,6 +350,7 @@ main(int argc, char **argv)
 		{"disable-dollar-quoting", no_argument, &disable_dollar_quoting, 1},
 		{"disable-triggers", no_argument, &disable_triggers, 1},
 		{"exclude-table-data", required_argument, NULL, 4},
+		{"if-exists", no_argument, &if_exists, 1},
 		{"inserts", no_argument, &dump_inserts, 1},
 		{"lock-wait-timeout", required_argument, NULL, 2},
 		{"no-tablespaces", no_argument, &outputNoTablespaces, 1},
@@ -577,6 +579,9 @@ main(int argc, char **argv)
 		exit_nicely(1);
 	}
 
+	if (if_exists && !outputClean)
+		exit_horribly(NULL, "option --if-exists requires -c/--clean option\n");
+
 	/* Identify archive format to emit */
 	archiveFormat = parseArchiveFormat(format, &archiveMode);
 
@@ -809,6 +814,7 @@ main(int argc, char **argv)
 	ropt->dropSchema = outputClean;
 	ropt->dataOnly = dataOnly;
 	ropt->schemaOnly = schemaOnly;
+	ropt->if_exists = if_exists;
 	ropt->dumpSections = dumpSections;
 	ropt->aclsSkip = aclsSkip;
 	ropt->superuser = outputSuperuser;
@@ -890,6 +896,7 @@ help(const char *progname)
 	printf(_("  --disable-dollar-quoting     disable dollar quoting, use SQL standard quoting\n"));
 	printf(_("  --disable-triggers           disable triggers during data-only restore\n"));
 	printf(_("  --exclude-table-data=TABLE   do NOT dump data for the named table(s)\n"));
+	printf(_("  --if-exists                  use IF EXISTS when dropping objects\n"));
 	printf(_("  --inserts                    dump data as INSERT commands, rather than COPY\n"));
 	printf(_("  --no-security-labels         do not dump security label assignments\n"));
 	printf(_("  --no-synchronized-snapshots  do not use synchronized snapshots in parallel jobs\n"));
@@ -2290,7 +2297,8 @@ dumpDatabase(Archive *fout)
 
 	}
 
-	appendPQExpBuffer(delQry, "DROP DATABASE %s;\n",
+	appendPQExpBuffer(delQry, "DROP DATABASE %s%s;\n",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(datname));
 
 	dbDumpId = createDumpId();
@@ -7894,7 +7902,9 @@ dumpNamespace(Archive *fout, NamespaceInfo *nspinfo)
 
 	qnspname = pg_strdup(fmtId(nspinfo->dobj.name));
 
-	appendPQExpBuffer(delq, "DROP SCHEMA %s;\n", qnspname);
+	appendPQExpBuffer(delq, "DROP SCHEMA %s%s;\n",
+						    if_exists ? "IF EXISTS " : "",
+						    qnspname);
 
 	appendPQExpBuffer(q, "CREATE SCHEMA %s;\n", qnspname);
 
@@ -7953,7 +7963,9 @@ dumpExtension(Archive *fout, ExtensionInfo *extinfo)
 
 	qextname = pg_strdup(fmtId(extinfo->dobj.name));
 
-	appendPQExpBuffer(delq, "DROP EXTENSION %s;\n", qextname);
+	appendPQExpBuffer(delq, "DROP EXTENSION %s%s;\n",
+						    if_exists ? "IF EXISTS " : "",
+						    qextname);
 
 	if (!binary_upgrade)
 	{
@@ -8127,7 +8139,8 @@ dumpEnumType(Archive *fout, TypeInfo *tyinfo)
 	 * CASCADE shouldn't be required here as for normal types since the I/O
 	 * functions are generic and do not get dropped.
 	 */
-	appendPQExpBuffer(delq, "DROP TYPE %s.",
+	appendPQExpBuffer(delq, "DROP TYPE %s%s.",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tyinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, "%s;\n",
 					  qtypname);
@@ -8257,7 +8270,8 @@ dumpRangeType(Archive *fout, TypeInfo *tyinfo)
 	 * CASCADE shouldn't be required here as for normal types since the I/O
 	 * functions are generic and do not get dropped.
 	 */
-	appendPQExpBuffer(delq, "DROP TYPE %s.",
+	appendPQExpBuffer(delq, "DROP TYPE %s%s.",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tyinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, "%s;\n",
 					  qtypname);
@@ -8596,7 +8610,8 @@ dumpBaseType(Archive *fout, TypeInfo *tyinfo)
 	 * the type and its I/O functions makes it impossible to drop the type any
 	 * other way.
 	 */
-	appendPQExpBuffer(delq, "DROP TYPE %s.",
+	appendPQExpBuffer(delq, "DROP TYPE %s%s.",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tyinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, "%s CASCADE;\n",
 					  qtypname);
@@ -8855,7 +8870,8 @@ dumpDomain(Archive *fout, TypeInfo *tyinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP DOMAIN %s.",
+	appendPQExpBuffer(delq, "DROP DOMAIN %s%s.",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tyinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, "%s;\n",
 					  qtypname);
@@ -9069,7 +9085,8 @@ dumpCompositeType(Archive *fout, TypeInfo *tyinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP TYPE %s.",
+	appendPQExpBuffer(delq, "DROP TYPE %s%s.",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tyinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, "%s;\n",
 					  qtypname);
@@ -9379,7 +9396,8 @@ dumpProcLang(Archive *fout, ProcLangInfo *plang)
 	else
 		lanschema = NULL;
 
-	appendPQExpBuffer(delqry, "DROP PROCEDURAL LANGUAGE %s;\n",
+	appendPQExpBuffer(delqry, "DROP PROCEDURAL LANGUAGE %s%s;\n",
+					  if_exists ? "IF EXISTS " : "",
 					  qlanname);
 
 	if (useParams)
@@ -9923,7 +9941,8 @@ dumpFunc(Archive *fout, FuncInfo *finfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delqry, "DROP FUNCTION %s.%s;\n",
+	appendPQExpBuffer(delqry, "DROP FUNCTION %s%s.%s;\n",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(finfo->dobj.namespace->dobj.name),
 					  funcsig);
 
@@ -10141,7 +10160,8 @@ dumpCast(Archive *fout, CastInfo *cast)
 	delqry = createPQExpBuffer();
 	labelq = createPQExpBuffer();
 
-	appendPQExpBuffer(delqry, "DROP CAST (%s AS %s);\n",
+	appendPQExpBuffer(delqry, "DROP CAST %s(%s AS %s);\n",
+					if_exists ? "IF EXISTS " : "",
 					getFormattedTypeName(fout, cast->castsource, zeroAsNone),
 				   getFormattedTypeName(fout, cast->casttarget, zeroAsNone));
 
@@ -10411,7 +10431,8 @@ dumpOpr(Archive *fout, OprInfo *oprinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP OPERATOR %s.%s;\n",
+	appendPQExpBuffer(delq, "DROP OPERATOR %s%s.%s;\n",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(oprinfo->dobj.namespace->dobj.name),
 					  oprid->data);
 
@@ -10696,7 +10717,8 @@ dumpOpclass(Archive *fout, OpclassInfo *opcinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP OPERATOR CLASS %s",
+	appendPQExpBuffer(delq, "DROP OPERATOR CLASS %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(opcinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s",
 					  fmtId(opcinfo->dobj.name));
@@ -11140,7 +11162,8 @@ dumpOpfamily(Archive *fout, OpfamilyInfo *opfinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP OPERATOR FAMILY %s",
+	appendPQExpBuffer(delq, "DROP OPERATOR FAMILY %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(opfinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s",
 					  fmtId(opfinfo->dobj.name));
@@ -11314,7 +11337,8 @@ dumpCollation(Archive *fout, CollInfo *collinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP COLLATION %s",
+	appendPQExpBuffer(delq, "DROP COLLATION %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(collinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s;\n",
 					  fmtId(collinfo->dobj.name));
@@ -11411,7 +11435,8 @@ dumpConversion(Archive *fout, ConvInfo *convinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP CONVERSION %s",
+	appendPQExpBuffer(delq, "DROP CONVERSION %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(convinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s;\n",
 					  fmtId(convinfo->dobj.name));
@@ -11723,7 +11748,8 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP AGGREGATE %s.%s;\n",
+	appendPQExpBuffer(delq, "DROP AGGREGATE %s%s.%s;\n",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(agginfo->aggfn.dobj.namespace->dobj.name),
 					  aggsig);
 
@@ -11822,7 +11848,8 @@ dumpTSParser(Archive *fout, TSParserInfo *prsinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP TEXT SEARCH PARSER %s",
+	appendPQExpBuffer(delq, "DROP TEXT SEARCH PARSER %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(prsinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s;\n",
 					  fmtId(prsinfo->dobj.name));
@@ -11909,7 +11936,8 @@ dumpTSDictionary(Archive *fout, TSDictInfo *dictinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP TEXT SEARCH DICTIONARY %s",
+	appendPQExpBuffer(delq, "DROP TEXT SEARCH DICTIONARY %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(dictinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s;\n",
 					  fmtId(dictinfo->dobj.name));
@@ -11975,7 +12003,8 @@ dumpTSTemplate(Archive *fout, TSTemplateInfo *tmplinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP TEXT SEARCH TEMPLATE %s",
+	appendPQExpBuffer(delq, "DROP TEXT SEARCH TEMPLATE %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tmplinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s;\n",
 					  fmtId(tmplinfo->dobj.name));
@@ -12103,7 +12132,8 @@ dumpTSConfig(Archive *fout, TSConfigInfo *cfginfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP TEXT SEARCH CONFIGURATION %s",
+	appendPQExpBuffer(delq, "DROP TEXT SEARCH CONFIGURATION %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(cfginfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s;\n",
 					  fmtId(cfginfo->dobj.name));
@@ -12179,7 +12209,8 @@ dumpForeignDataWrapper(Archive *fout, FdwInfo *fdwinfo)
 
 	appendPQExpBufferStr(q, ";\n");
 
-	appendPQExpBuffer(delq, "DROP FOREIGN DATA WRAPPER %s;\n",
+	appendPQExpBuffer(delq, "DROP FOREIGN DATA WRAPPER %s%s;\n",
+					  if_exists ? "IF EXISTS " : "",
 					  qfdwname);
 
 	appendPQExpBuffer(labelq, "FOREIGN DATA WRAPPER %s",
@@ -12272,7 +12303,8 @@ dumpForeignServer(Archive *fout, ForeignServerInfo *srvinfo)
 
 	appendPQExpBufferStr(q, ";\n");
 
-	appendPQExpBuffer(delq, "DROP SERVER %s;\n",
+	appendPQExpBuffer(delq, "DROP SERVER %s%s;\n",
+					  if_exists ? "IF EXISTS " : "",
 					  qsrvname);
 
 	appendPQExpBuffer(labelq, "SERVER %s", qsrvname);
@@ -12390,7 +12422,9 @@ dumpUserMappings(Archive *fout,
 		appendPQExpBufferStr(q, ";\n");
 
 		resetPQExpBuffer(delq);
-		appendPQExpBuffer(delq, "DROP USER MAPPING FOR %s", fmtId(usename));
+		appendPQExpBuffer(delq, "DROP USER MAPPING %sFOR %s",
+							    if_exists ? "IF EXISTS " : "",
+							    fmtId(usename));
 		appendPQExpBuffer(delq, " SERVER %s;\n", fmtId(servername));
 
 		resetPQExpBuffer(tag);
@@ -12997,7 +13031,8 @@ dumpTableSchema(Archive *fout, TableInfo *tbinfo)
 		 * DROP must be fully qualified in case same name appears in
 		 * pg_catalog
 		 */
-		appendPQExpBuffer(delq, "DROP VIEW %s.",
+		appendPQExpBuffer(delq, "DROP VIEW %s%s.",
+						  if_exists ? "IF EXISTS " : "",
 						  fmtId(tbinfo->dobj.namespace->dobj.name));
 		appendPQExpBuffer(delq, "%s;\n",
 						  fmtId(tbinfo->dobj.name));
@@ -13074,7 +13109,8 @@ dumpTableSchema(Archive *fout, TableInfo *tbinfo)
 		 * DROP must be fully qualified in case same name appears in
 		 * pg_catalog
 		 */
-		appendPQExpBuffer(delq, "DROP %s %s.", reltypename,
+		appendPQExpBuffer(delq, "DROP %s %s%s.", reltypename,
+						  if_exists ? "IF EXISTS " : "",
 						  fmtId(tbinfo->dobj.namespace->dobj.name));
 		appendPQExpBuffer(delq, "%s;\n",
 						  fmtId(tbinfo->dobj.name));
@@ -13627,7 +13663,8 @@ dumpAttrDef(Archive *fout, AttrDefInfo *adinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "ALTER TABLE %s.",
+	appendPQExpBuffer(delq, "ALTER TABLE %s%s.",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tbinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, "%s ",
 					  fmtId(tbinfo->dobj.name));
@@ -13743,7 +13780,8 @@ dumpIndex(Archive *fout, IndxInfo *indxinfo)
 		 * DROP must be fully qualified in case same name appears in
 		 * pg_catalog
 		 */
-		appendPQExpBuffer(delq, "DROP INDEX %s.",
+		appendPQExpBuffer(delq, "DROP INDEX %s%s.",
+						  if_exists ? "IF EXISTS " : "",
 						  fmtId(tbinfo->dobj.namespace->dobj.name));
 		appendPQExpBuffer(delq, "%s;\n",
 						  fmtId(indxinfo->dobj.name));
@@ -13864,7 +13902,8 @@ dumpConstraint(Archive *fout, ConstraintInfo *coninfo)
 		 * DROP must be fully qualified in case same name appears in
 		 * pg_catalog
 		 */
-		appendPQExpBuffer(delq, "ALTER TABLE ONLY %s.",
+		appendPQExpBuffer(delq, "ALTER TABLE %sONLY %s.",
+						  if_exists ? "IF EXISTS " : "",
 						  fmtId(tbinfo->dobj.namespace->dobj.name));
 		appendPQExpBuffer(delq, "%s ",
 						  fmtId(tbinfo->dobj.name));
@@ -13897,7 +13936,8 @@ dumpConstraint(Archive *fout, ConstraintInfo *coninfo)
 		 * DROP must be fully qualified in case same name appears in
 		 * pg_catalog
 		 */
-		appendPQExpBuffer(delq, "ALTER TABLE ONLY %s.",
+		appendPQExpBuffer(delq, "ALTER TABLE %sONLY %s.",
+						  if_exists ? "IF EXISTS " : "",
 						  fmtId(tbinfo->dobj.namespace->dobj.name));
 		appendPQExpBuffer(delq, "%s ",
 						  fmtId(tbinfo->dobj.name));
@@ -14166,7 +14206,8 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delqry, "DROP SEQUENCE %s.",
+	appendPQExpBuffer(delqry, "DROP SEQUENCE %s%s.",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tbinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delqry, "%s;\n",
 					  fmtId(tbinfo->dobj.name));
@@ -14362,7 +14403,8 @@ dumpTrigger(Archive *fout, TriggerInfo *tginfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delqry, "DROP TRIGGER %s ",
+	appendPQExpBuffer(delqry, "DROP TRIGGER %s%s ",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tginfo->dobj.name));
 	appendPQExpBuffer(delqry, "ON %s.",
 					  fmtId(tbinfo->dobj.namespace->dobj.name));
@@ -14710,7 +14752,8 @@ dumpRule(Archive *fout, RuleInfo *rinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delcmd, "DROP RULE %s ",
+	appendPQExpBuffer(delcmd, "DROP RULE %s%s ",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(rinfo->dobj.name));
 	appendPQExpBuffer(delcmd, "ON %s.",
 					  fmtId(tbinfo->dobj.namespace->dobj.name));
diff --git a/src/bin/pg_dump/pg_dumpall.c b/src/bin/pg_dump/pg_dumpall.c
index 193c1a0..335fdde 100644
--- a/src/bin/pg_dump/pg_dumpall.c
+++ b/src/bin/pg_dump/pg_dumpall.c
@@ -73,6 +73,7 @@ static int	binary_upgrade = 0;
 static int	column_inserts = 0;
 static int	disable_dollar_quoting = 0;
 static int	disable_triggers = 0;
+static int	if_exists = 0;
 static int	inserts = 0;
 static int	no_tablespaces = 0;
 static int	use_setsessauth = 0;
@@ -119,6 +120,7 @@ main(int argc, char *argv[])
 		{"column-inserts", no_argument, &column_inserts, 1},
 		{"disable-dollar-quoting", no_argument, &disable_dollar_quoting, 1},
 		{"disable-triggers", no_argument, &disable_triggers, 1},
+		{"if-exists", no_argument, &if_exists, 1},
 		{"inserts", no_argument, &inserts, 1},
 		{"lock-wait-timeout", required_argument, NULL, 2},
 		{"no-tablespaces", no_argument, &no_tablespaces, 1},
@@ -352,6 +354,8 @@ main(int argc, char *argv[])
 		appendPQExpBufferStr(pgdumpopts, " --disable-dollar-quoting");
 	if (disable_triggers)
 		appendPQExpBufferStr(pgdumpopts, " --disable-triggers");
+	if (if_exists)
+		appendPQExpBufferStr(pgdumpopts, " --if-exists");
 	if (inserts)
 		appendPQExpBufferStr(pgdumpopts, " --inserts");
 	if (no_tablespaces)
@@ -564,6 +568,7 @@ help(void)
 	printf(_("  --column-inserts             dump data as INSERT commands with column names\n"));
 	printf(_("  --disable-dollar-quoting     disable dollar quoting, use SQL standard quoting\n"));
 	printf(_("  --disable-triggers           disable triggers during data-only restore\n"));
+	printf(_("  --if-exists                  use IF EXISTS when dropping objects\n"));
 	printf(_("  --inserts                    dump data as INSERT commands, rather than COPY\n"));
 	printf(_("  --no-security-labels         do not dump security label assignments\n"));
 	printf(_("  --no-tablespaces             do not dump tablespace assignments\n"));
diff --git a/src/bin/pg_dump/pg_restore.c b/src/bin/pg_dump/pg_restore.c
index 2648003..74f9c2a 100644
--- a/src/bin/pg_dump/pg_restore.c
+++ b/src/bin/pg_dump/pg_restore.c
@@ -76,6 +76,7 @@ main(int argc, char **argv)
 	Archive    *AH;
 	char	   *inputFileSpec;
 	static int	disable_triggers = 0;
+	static int	if_exists = 0;
 	static int	no_data_for_failed_tables = 0;
 	static int	outputNoTablespaces = 0;
 	static int	use_setsessauth = 0;
@@ -116,6 +117,7 @@ main(int argc, char **argv)
 		 * the following options don't have an equivalent short option letter
 		 */
 		{"disable-triggers", no_argument, &disable_triggers, 1},
+		{"if-exists", no_argument, &if_exists, 1},
 		{"no-data-for-failed-tables", no_argument, &no_data_for_failed_tables, 1},
 		{"no-tablespaces", no_argument, &outputNoTablespaces, 1},
 		{"role", required_argument, NULL, 2},
@@ -342,6 +344,14 @@ main(int argc, char **argv)
 	opts->use_setsessauth = use_setsessauth;
 	opts->no_security_labels = no_security_labels;
 
+	if (if_exists && !opts->dropSchema)
+	{
+		fprintf(stderr, _("%s: option --if-exists requires -c/--clean option\n"),
+				progname);
+		exit_nicely(1);
+	}
+	opts->if_exists = if_exists;
+
 	if (opts->formatName)
 	{
 		switch (opts->formatName[0])
@@ -456,6 +466,7 @@ usage(const char *progname)
 	printf(_("  -x, --no-privileges          skip restoration of access privileges (grant/revoke)\n"));
 	printf(_("  -1, --single-transaction     restore as a single transaction\n"));
 	printf(_("  --disable-triggers           disable triggers during data-only restore\n"));
+	printf(_("  --if-exists                  use IF EXISTS when dropping objects\n"));
 	printf(_("  --no-data-for-failed-tables  do not restore data of tables that could not be\n"
 			 "                               created\n"));
 	printf(_("  --no-security-labels         do not restore security labels\n"));

commit ccf1d230edc569c1a27c41065511269ee99898bd
Author: Pavel Stehule <pavel.stehule@gooddata.com>
Date:   Sat Jan 25 13:38:22 2014 +0100

    fixes related to review

diff --git a/doc/src/sgml/ref/pg_dump.sgml b/doc/src/sgml/ref/pg_dump.sgml
index 8d45f24..c39767b 100644
--- a/doc/src/sgml/ref/pg_dump.sgml
+++ b/doc/src/sgml/ref/pg_dump.sgml
@@ -650,6 +650,16 @@ PostgreSQL documentation
      </varlistentry>
 
      <varlistentry>
+      <term><option>--if-exists</option></term>
+      <listitem>
+       <para>
+        It uses conditional commands (with <literal>IF EXISTS</literal>
+        clause) for cleaning database schema.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><option>--disable-dollar-quoting</></term>
       <listitem>
        <para>
diff --git a/doc/src/sgml/ref/pg_dumpall.sgml b/doc/src/sgml/ref/pg_dumpall.sgml
index 5c6a101..ba6583d 100644
--- a/doc/src/sgml/ref/pg_dumpall.sgml
+++ b/doc/src/sgml/ref/pg_dumpall.sgml
@@ -301,6 +301,16 @@ PostgreSQL documentation
      </varlistentry>
 
      <varlistentry>
+      <term><option>--if-exists</option></term>
+      <listitem>
+       <para>
+        It uses conditional commands (with <literal>IF EXISTS</literal>
+        clause) for cleaning database schema.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><option>--inserts</option></term>
       <listitem>
        <para>
diff --git a/doc/src/sgml/ref/pg_restore.sgml b/doc/src/sgml/ref/pg_restore.sgml
index 717da42..55326d5 100644
--- a/doc/src/sgml/ref/pg_restore.sgml
+++ b/doc/src/sgml/ref/pg_restore.sgml
@@ -490,6 +490,16 @@
      </varlistentry>
 
      <varlistentry>
+      <term><option>--if-exists</option></term>
+      <listitem>
+       <para>
+        It uses conditional commands (with <literal>IF EXISTS</literal>
+        clause) for cleaning database schema.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><option>--no-data-for-failed-tables</option></term>
       <listitem>
        <para>
diff --git a/src/bin/pg_dump/pg_backup.h b/src/bin/pg_dump/pg_backup.h
index 6927968..83f7216 100644
--- a/src/bin/pg_dump/pg_backup.h
+++ b/src/bin/pg_dump/pg_backup.h
@@ -113,6 +113,7 @@ typedef struct _restoreOptions
 	char	   *superuser;		/* Username to use as superuser */
 	char	   *use_role;		/* Issue SET ROLE to this */
 	int			dropSchema;
+	int			if_exists;
 	const char *filename;
 	int			dataOnly;
 	int			schemaOnly;
diff --git a/src/bin/pg_dump/pg_backup_archiver.c b/src/bin/pg_dump/pg_backup_archiver.c
index 7fc0288..b1bf72c 100644
--- a/src/bin/pg_dump/pg_backup_archiver.c
+++ b/src/bin/pg_dump/pg_backup_archiver.c
@@ -413,8 +413,63 @@ RestoreArchive(Archive *AHX)
 				/* Select owner and schema as necessary */
 				_becomeOwner(AH, te);
 				_selectOutputSchema(AH, te->namespace);
-				/* Drop it */
-				ahprintf(AH, "%s", te->dropStmt);
+
+				if (*te->dropStmt != '\0')
+				{
+					/* Inject IF EXISTS clause to DROP part when it is required. */
+					if (ropt->if_exists)
+					{
+						char buffer[40];
+						char *mark;
+
+						/*
+						 * Descriptor string should not be same as object
+						 * specifier for DROP STATEMENT.
+						 */
+						if (strcmp(te->desc, "DEFAULT") == 0)
+						{
+							mark = NULL;
+						}
+						else
+						{
+							if (strcmp(te->desc, "CONSTRAINT") == 0 ||
+									 strcmp(te->desc, "CHECK CONSTRAINT") == 0 ||
+									 strcmp(te->desc, "FK CONSTRAINT") == 0)
+								strcpy(buffer, "DROP CONSTRAINT");
+							else if (strcmp(te->desc, "OPERATOR") == 0 ||
+									 strcmp(te->desc, "OPERATOR CLASS") == 0 ||
+									strcmp(te->desc, "OPERATOR FAMILY") == 0)
+								strcmp(buffer, "DROP OPERATOR");
+							else
+								snprintf(buffer, sizeof(buffer), "DROP %s",
+													 te->desc);
+
+							mark = strstr(te->dropStmt, buffer);
+						}
+
+						if (mark != NULL)
+						{
+							size_t l = strlen(buffer);
+
+							/*
+							 * Insert IF EXISTS clause when it is not
+							 * used yet.
+							 */
+							if (strncmp(mark + l, " IF EXISTS", 10) != 0)
+							{
+								*mark = '\0';
+
+								ahprintf(AH, "%s", te->dropStmt);
+								ahprintf(AH, "%s IF EXISTS", buffer);
+								ahprintf(AH, "%s", mark + l);
+							}
+							else
+								ahprintf(AH, "%s", te->dropStmt);
+						}
+						else
+							ahprintf(AH, "%s", te->dropStmt);
+					}
+				}
 			}
 		}
 
@@ -2942,9 +2997,49 @@ _getObjectDescription(PQExpBuffer buf, TocEntry *te, ArchiveHandle *AH)
 		strcmp(type, "OPERATOR CLASS") == 0 ||
 		strcmp(type, "OPERATOR FAMILY") == 0)
 	{
-		/* Chop "DROP " off the front and make a modifiable copy */
-		char	   *first = pg_strdup(te->dropStmt + 5);
-		char	   *last;
+		char	    *first;
+		char	    *last;
+
+		/*
+		 * Object description is based on dropStmt statement which may have
+		 * IF EXISTS clause.  Thus we need to update an offset such that it
+		 * won't be included in the object description.
+		 */
+		if (strstr(te->dropStmt, "IF EXISTS") != NULL)
+		{
+			char buffer[40];
+			size_t   l;
+			char *supertype;
+
+			/*
+			 * Be sure, so IF EXISTS is used as DROP stmt option.
+			 * Use only first word from type var. CLASS or FAMILY
+			 * should not be used here.
+			 */
+			if (strncmp(type, "OPERATOR", 8) == 0)
+				supertype = "OPERATOR";
+			else
+				supertype = type;
+
+			snprintf(buffer, sizeof(buffer), "DROP %s IF EXISTS", supertype);
+
+			l = strlen(buffer);
+
+			if (strncmp(te->dropStmt, buffer, l) == 0)
+			{
+				/* append command type to target type */
+				appendPQExpBufferStr(buf, supertype);
+
+				/* skip first n chars, and create a modifiable copy */
+				first = pg_strdup(te->dropStmt + l);
+			}
+			else
+				/* DROP IF EXISTS pattern is not applicable on dropStmt */
+				first = pg_strdup(te->dropStmt + 5);
+		}
+		else
+			/* IF EXISTS clause was not used, simple solution */
+			first = pg_strdup(te->dropStmt + 5);
 
 		/* point to last character in string */
 		last = first + strlen(first) - 1;
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 3862f05..1227d55 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -136,6 +136,7 @@ static int	binary_upgrade = 0;
 static int	disable_dollar_quoting = 0;
 static int	dump_inserts = 0;
 static int	column_inserts = 0;
+static int	if_exists = 0;
 static int	no_security_labels = 0;
 static int	no_synchronized_snapshots = 0;
 static int	no_unlogged_table_data = 0;
@@ -349,6 +350,7 @@ main(int argc, char **argv)
 		{"disable-dollar-quoting", no_argument, &disable_dollar_quoting, 1},
 		{"disable-triggers", no_argument, &disable_triggers, 1},
 		{"exclude-table-data", required_argument, NULL, 4},
+		{"if-exists", no_argument, &if_exists, 1},
 		{"inserts", no_argument, &dump_inserts, 1},
 		{"lock-wait-timeout", required_argument, NULL, 2},
 		{"no-tablespaces", no_argument, &outputNoTablespaces, 1},
@@ -577,6 +579,9 @@ main(int argc, char **argv)
 		exit_nicely(1);
 	}
 
+	if (if_exists && !outputClean)
+		exit_horribly(NULL, "option --if-exists requires -c/--clean option\n");
+
 	/* Identify archive format to emit */
 	archiveFormat = parseArchiveFormat(format, &archiveMode);
 
@@ -809,6 +814,7 @@ main(int argc, char **argv)
 	ropt->dropSchema = outputClean;
 	ropt->dataOnly = dataOnly;
 	ropt->schemaOnly = schemaOnly;
+	ropt->if_exists = if_exists;
 	ropt->dumpSections = dumpSections;
 	ropt->aclsSkip = aclsSkip;
 	ropt->superuser = outputSuperuser;
@@ -890,6 +896,7 @@ help(const char *progname)
 	printf(_("  --disable-dollar-quoting     disable dollar quoting, use SQL standard quoting\n"));
 	printf(_("  --disable-triggers           disable triggers during data-only restore\n"));
 	printf(_("  --exclude-table-data=TABLE   do NOT dump data for the named table(s)\n"));
+	printf(_("  --if-exists                  use IF EXISTS when dropping objects\n"));
 	printf(_("  --inserts                    dump data as INSERT commands, rather than COPY\n"));
 	printf(_("  --no-security-labels         do not dump security label assignments\n"));
 	printf(_("  --no-synchronized-snapshots  do not use synchronized snapshots in parallel jobs\n"));
@@ -2290,7 +2297,8 @@ dumpDatabase(Archive *fout)
 
 	}
 
-	appendPQExpBuffer(delQry, "DROP DATABASE %s;\n",
+	appendPQExpBuffer(delQry, "DROP DATABASE %s%s;\n",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(datname));
 
 	dbDumpId = createDumpId();
@@ -7894,7 +7902,9 @@ dumpNamespace(Archive *fout, NamespaceInfo *nspinfo)
 
 	qnspname = pg_strdup(fmtId(nspinfo->dobj.name));
 
-	appendPQExpBuffer(delq, "DROP SCHEMA %s;\n", qnspname);
+	appendPQExpBuffer(delq, "DROP SCHEMA %s%s;\n",
+						    if_exists ? "IF EXISTS " : "",
+						    qnspname);
 
 	appendPQExpBuffer(q, "CREATE SCHEMA %s;\n", qnspname);
 
@@ -7953,7 +7963,9 @@ dumpExtension(Archive *fout, ExtensionInfo *extinfo)
 
 	qextname = pg_strdup(fmtId(extinfo->dobj.name));
 
-	appendPQExpBuffer(delq, "DROP EXTENSION %s;\n", qextname);
+	appendPQExpBuffer(delq, "DROP EXTENSION %s%s;\n",
+						    if_exists ? "IF EXISTS " : "",
+						    qextname);
 
 	if (!binary_upgrade)
 	{
@@ -8127,7 +8139,8 @@ dumpEnumType(Archive *fout, TypeInfo *tyinfo)
 	 * CASCADE shouldn't be required here as for normal types since the I/O
 	 * functions are generic and do not get dropped.
 	 */
-	appendPQExpBuffer(delq, "DROP TYPE %s.",
+	appendPQExpBuffer(delq, "DROP TYPE %s%s.",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tyinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, "%s;\n",
 					  qtypname);
@@ -8257,7 +8270,8 @@ dumpRangeType(Archive *fout, TypeInfo *tyinfo)
 	 * CASCADE shouldn't be required here as for normal types since the I/O
 	 * functions are generic and do not get dropped.
 	 */
-	appendPQExpBuffer(delq, "DROP TYPE %s.",
+	appendPQExpBuffer(delq, "DROP TYPE %s%s.",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tyinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, "%s;\n",
 					  qtypname);
@@ -8596,7 +8610,8 @@ dumpBaseType(Archive *fout, TypeInfo *tyinfo)
 	 * the type and its I/O functions makes it impossible to drop the type any
 	 * other way.
 	 */
-	appendPQExpBuffer(delq, "DROP TYPE %s.",
+	appendPQExpBuffer(delq, "DROP TYPE %s%s.",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tyinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, "%s CASCADE;\n",
 					  qtypname);
@@ -8855,7 +8870,8 @@ dumpDomain(Archive *fout, TypeInfo *tyinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP DOMAIN %s.",
+	appendPQExpBuffer(delq, "DROP DOMAIN %s%s.",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tyinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, "%s;\n",
 					  qtypname);
@@ -9069,7 +9085,8 @@ dumpCompositeType(Archive *fout, TypeInfo *tyinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP TYPE %s.",
+	appendPQExpBuffer(delq, "DROP TYPE %s%s.",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tyinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, "%s;\n",
 					  qtypname);
@@ -9379,7 +9396,8 @@ dumpProcLang(Archive *fout, ProcLangInfo *plang)
 	else
 		lanschema = NULL;
 
-	appendPQExpBuffer(delqry, "DROP PROCEDURAL LANGUAGE %s;\n",
+	appendPQExpBuffer(delqry, "DROP PROCEDURAL LANGUAGE %s%s;\n",
+					  if_exists ? "IF EXISTS " : "",
 					  qlanname);
 
 	if (useParams)
@@ -9923,7 +9941,8 @@ dumpFunc(Archive *fout, FuncInfo *finfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delqry, "DROP FUNCTION %s.%s;\n",
+	appendPQExpBuffer(delqry, "DROP FUNCTION %s%s.%s;\n",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(finfo->dobj.namespace->dobj.name),
 					  funcsig);
 
@@ -10141,7 +10160,8 @@ dumpCast(Archive *fout, CastInfo *cast)
 	delqry = createPQExpBuffer();
 	labelq = createPQExpBuffer();
 
-	appendPQExpBuffer(delqry, "DROP CAST (%s AS %s);\n",
+	appendPQExpBuffer(delqry, "DROP CAST %s(%s AS %s);\n",
+					if_exists ? "IF EXISTS " : "",
 					getFormattedTypeName(fout, cast->castsource, zeroAsNone),
 				   getFormattedTypeName(fout, cast->casttarget, zeroAsNone));
 
@@ -10411,7 +10431,8 @@ dumpOpr(Archive *fout, OprInfo *oprinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP OPERATOR %s.%s;\n",
+	appendPQExpBuffer(delq, "DROP OPERATOR %s%s.%s;\n",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(oprinfo->dobj.namespace->dobj.name),
 					  oprid->data);
 
@@ -10696,7 +10717,8 @@ dumpOpclass(Archive *fout, OpclassInfo *opcinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP OPERATOR CLASS %s",
+	appendPQExpBuffer(delq, "DROP OPERATOR CLASS %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(opcinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s",
 					  fmtId(opcinfo->dobj.name));
@@ -11140,7 +11162,8 @@ dumpOpfamily(Archive *fout, OpfamilyInfo *opfinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP OPERATOR FAMILY %s",
+	appendPQExpBuffer(delq, "DROP OPERATOR FAMILY %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(opfinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s",
 					  fmtId(opfinfo->dobj.name));
@@ -11314,7 +11337,8 @@ dumpCollation(Archive *fout, CollInfo *collinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP COLLATION %s",
+	appendPQExpBuffer(delq, "DROP COLLATION %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(collinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s;\n",
 					  fmtId(collinfo->dobj.name));
@@ -11411,7 +11435,8 @@ dumpConversion(Archive *fout, ConvInfo *convinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP CONVERSION %s",
+	appendPQExpBuffer(delq, "DROP CONVERSION %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(convinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s;\n",
 					  fmtId(convinfo->dobj.name));
@@ -11723,7 +11748,8 @@ dumpAgg(Archive *fout, AggInfo *agginfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP AGGREGATE %s.%s;\n",
+	appendPQExpBuffer(delq, "DROP AGGREGATE %s%s.%s;\n",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(agginfo->aggfn.dobj.namespace->dobj.name),
 					  aggsig);
 
@@ -11822,7 +11848,8 @@ dumpTSParser(Archive *fout, TSParserInfo *prsinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP TEXT SEARCH PARSER %s",
+	appendPQExpBuffer(delq, "DROP TEXT SEARCH PARSER %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(prsinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s;\n",
 					  fmtId(prsinfo->dobj.name));
@@ -11909,7 +11936,8 @@ dumpTSDictionary(Archive *fout, TSDictInfo *dictinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP TEXT SEARCH DICTIONARY %s",
+	appendPQExpBuffer(delq, "DROP TEXT SEARCH DICTIONARY %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(dictinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s;\n",
 					  fmtId(dictinfo->dobj.name));
@@ -11975,7 +12003,8 @@ dumpTSTemplate(Archive *fout, TSTemplateInfo *tmplinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP TEXT SEARCH TEMPLATE %s",
+	appendPQExpBuffer(delq, "DROP TEXT SEARCH TEMPLATE %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tmplinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s;\n",
 					  fmtId(tmplinfo->dobj.name));
@@ -12103,7 +12132,8 @@ dumpTSConfig(Archive *fout, TSConfigInfo *cfginfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "DROP TEXT SEARCH CONFIGURATION %s",
+	appendPQExpBuffer(delq, "DROP TEXT SEARCH CONFIGURATION %s%s",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(cfginfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, ".%s;\n",
 					  fmtId(cfginfo->dobj.name));
@@ -12179,7 +12209,8 @@ dumpForeignDataWrapper(Archive *fout, FdwInfo *fdwinfo)
 
 	appendPQExpBufferStr(q, ";\n");
 
-	appendPQExpBuffer(delq, "DROP FOREIGN DATA WRAPPER %s;\n",
+	appendPQExpBuffer(delq, "DROP FOREIGN DATA WRAPPER %s%s;\n",
+					  if_exists ? "IF EXISTS " : "",
 					  qfdwname);
 
 	appendPQExpBuffer(labelq, "FOREIGN DATA WRAPPER %s",
@@ -12272,7 +12303,8 @@ dumpForeignServer(Archive *fout, ForeignServerInfo *srvinfo)
 
 	appendPQExpBufferStr(q, ";\n");
 
-	appendPQExpBuffer(delq, "DROP SERVER %s;\n",
+	appendPQExpBuffer(delq, "DROP SERVER %s%s;\n",
+					  if_exists ? "IF EXISTS " : "",
 					  qsrvname);
 
 	appendPQExpBuffer(labelq, "SERVER %s", qsrvname);
@@ -12390,7 +12422,9 @@ dumpUserMappings(Archive *fout,
 		appendPQExpBufferStr(q, ";\n");
 
 		resetPQExpBuffer(delq);
-		appendPQExpBuffer(delq, "DROP USER MAPPING FOR %s", fmtId(usename));
+		appendPQExpBuffer(delq, "DROP USER MAPPING %sFOR %s",
+							    if_exists ? "IF EXISTS " : "",
+							    fmtId(usename));
 		appendPQExpBuffer(delq, " SERVER %s;\n", fmtId(servername));
 
 		resetPQExpBuffer(tag);
@@ -12997,7 +13031,8 @@ dumpTableSchema(Archive *fout, TableInfo *tbinfo)
 		 * DROP must be fully qualified in case same name appears in
 		 * pg_catalog
 		 */
-		appendPQExpBuffer(delq, "DROP VIEW %s.",
+		appendPQExpBuffer(delq, "DROP VIEW %s%s.",
+						  if_exists ? "IF EXISTS " : "",
 						  fmtId(tbinfo->dobj.namespace->dobj.name));
 		appendPQExpBuffer(delq, "%s;\n",
 						  fmtId(tbinfo->dobj.name));
@@ -13074,7 +13109,8 @@ dumpTableSchema(Archive *fout, TableInfo *tbinfo)
 		 * DROP must be fully qualified in case same name appears in
 		 * pg_catalog
 		 */
-		appendPQExpBuffer(delq, "DROP %s %s.", reltypename,
+		appendPQExpBuffer(delq, "DROP %s %s%s.", reltypename,
+						  if_exists ? "IF EXISTS " : "",
 						  fmtId(tbinfo->dobj.namespace->dobj.name));
 		appendPQExpBuffer(delq, "%s;\n",
 						  fmtId(tbinfo->dobj.name));
@@ -13627,7 +13663,8 @@ dumpAttrDef(Archive *fout, AttrDefInfo *adinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delq, "ALTER TABLE %s.",
+	appendPQExpBuffer(delq, "ALTER TABLE %s%s.",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tbinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delq, "%s ",
 					  fmtId(tbinfo->dobj.name));
@@ -13743,7 +13780,8 @@ dumpIndex(Archive *fout, IndxInfo *indxinfo)
 		 * DROP must be fully qualified in case same name appears in
 		 * pg_catalog
 		 */
-		appendPQExpBuffer(delq, "DROP INDEX %s.",
+		appendPQExpBuffer(delq, "DROP INDEX %s%s.",
+						  if_exists ? "IF EXISTS " : "",
 						  fmtId(tbinfo->dobj.namespace->dobj.name));
 		appendPQExpBuffer(delq, "%s;\n",
 						  fmtId(indxinfo->dobj.name));
@@ -13864,7 +13902,8 @@ dumpConstraint(Archive *fout, ConstraintInfo *coninfo)
 		 * DROP must be fully qualified in case same name appears in
 		 * pg_catalog
 		 */
-		appendPQExpBuffer(delq, "ALTER TABLE ONLY %s.",
+		appendPQExpBuffer(delq, "ALTER TABLE %sONLY %s.",
+						  if_exists ? "IF EXISTS " : "",
 						  fmtId(tbinfo->dobj.namespace->dobj.name));
 		appendPQExpBuffer(delq, "%s ",
 						  fmtId(tbinfo->dobj.name));
@@ -13897,7 +13936,8 @@ dumpConstraint(Archive *fout, ConstraintInfo *coninfo)
 		 * DROP must be fully qualified in case same name appears in
 		 * pg_catalog
 		 */
-		appendPQExpBuffer(delq, "ALTER TABLE ONLY %s.",
+		appendPQExpBuffer(delq, "ALTER TABLE %sONLY %s.",
+						  if_exists ? "IF EXISTS " : "",
 						  fmtId(tbinfo->dobj.namespace->dobj.name));
 		appendPQExpBuffer(delq, "%s ",
 						  fmtId(tbinfo->dobj.name));
@@ -14166,7 +14206,8 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delqry, "DROP SEQUENCE %s.",
+	appendPQExpBuffer(delqry, "DROP SEQUENCE %s%s.",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tbinfo->dobj.namespace->dobj.name));
 	appendPQExpBuffer(delqry, "%s;\n",
 					  fmtId(tbinfo->dobj.name));
@@ -14362,7 +14403,8 @@ dumpTrigger(Archive *fout, TriggerInfo *tginfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delqry, "DROP TRIGGER %s ",
+	appendPQExpBuffer(delqry, "DROP TRIGGER %s%s ",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(tginfo->dobj.name));
 	appendPQExpBuffer(delqry, "ON %s.",
 					  fmtId(tbinfo->dobj.namespace->dobj.name));
@@ -14710,7 +14752,8 @@ dumpRule(Archive *fout, RuleInfo *rinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delcmd, "DROP RULE %s ",
+	appendPQExpBuffer(delcmd, "DROP RULE %s%s ",
+					  if_exists ? "IF EXISTS " : "",
 					  fmtId(rinfo->dobj.name));
 	appendPQExpBuffer(delcmd, "ON %s.",
 					  fmtId(tbinfo->dobj.namespace->dobj.name));
diff --git a/src/bin/pg_dump/pg_dumpall.c b/src/bin/pg_dump/pg_dumpall.c
index 193c1a0..335fdde 100644
--- a/src/bin/pg_dump/pg_dumpall.c
+++ b/src/bin/pg_dump/pg_dumpall.c
@@ -73,6 +73,7 @@ static int	binary_upgrade = 0;
 static int	column_inserts = 0;
 static int	disable_dollar_quoting = 0;
 static int	disable_triggers = 0;
+static int	if_exists = 0;
 static int	inserts = 0;
 static int	no_tablespaces = 0;
 static int	use_setsessauth = 0;
@@ -119,6 +120,7 @@ main(int argc, char *argv[])
 		{"column-inserts", no_argument, &column_inserts, 1},
 		{"disable-dollar-quoting", no_argument, &disable_dollar_quoting, 1},
 		{"disable-triggers", no_argument, &disable_triggers, 1},
+		{"if-exists", no_argument, &if_exists, 1},
 		{"inserts", no_argument, &inserts, 1},
 		{"lock-wait-timeout", required_argument, NULL, 2},
 		{"no-tablespaces", no_argument, &no_tablespaces, 1},
@@ -352,6 +354,8 @@ main(int argc, char *argv[])
 		appendPQExpBufferStr(pgdumpopts, " --disable-dollar-quoting");
 	if (disable_triggers)
 		appendPQExpBufferStr(pgdumpopts, " --disable-triggers");
+	if (if_exists)
+		appendPQExpBufferStr(pgdumpopts, " --if-exists");
 	if (inserts)
 		appendPQExpBufferStr(pgdumpopts, " --inserts");
 	if (no_tablespaces)
@@ -564,6 +568,7 @@ help(void)
 	printf(_("  --column-inserts             dump data as INSERT commands with column names\n"));
 	printf(_("  --disable-dollar-quoting     disable dollar quoting, use SQL standard quoting\n"));
 	printf(_("  --disable-triggers           disable triggers during data-only restore\n"));
+	printf(_("  --if-exists                  use IF EXISTS when dropping objects\n"));
 	printf(_("  --inserts                    dump data as INSERT commands, rather than COPY\n"));
 	printf(_("  --no-security-labels         do not dump security label assignments\n"));
 	printf(_("  --no-tablespaces             do not dump tablespace assignments\n"));
diff --git a/src/bin/pg_dump/pg_restore.c b/src/bin/pg_dump/pg_restore.c
index 2648003..74f9c2a 100644
--- a/src/bin/pg_dump/pg_restore.c
+++ b/src/bin/pg_dump/pg_restore.c
@@ -76,6 +76,7 @@ main(int argc, char **argv)
 	Archive    *AH;
 	char	   *inputFileSpec;
 	static int	disable_triggers = 0;
+	static int	if_exists = 0;
 	static int	no_data_for_failed_tables = 0;
 	static int	outputNoTablespaces = 0;
 	static int	use_setsessauth = 0;
@@ -116,6 +117,7 @@ main(int argc, char **argv)
 		 * the following options don't have an equivalent short option letter
 		 */
 		{"disable-triggers", no_argument, &disable_triggers, 1},
+		{"if-exists", no_argument, &if_exists, 1},
 		{"no-data-for-failed-tables", no_argument, &no_data_for_failed_tables, 1},
 		{"no-tablespaces", no_argument, &outputNoTablespaces, 1},
 		{"role", required_argument, NULL, 2},
@@ -342,6 +344,14 @@ main(int argc, char **argv)
 	opts->use_setsessauth = use_setsessauth;
 	opts->no_security_labels = no_security_labels;
 
+	if (if_exists && !opts->dropSchema)
+	{
+		fprintf(stderr, _("%s: option --if-exists requires -c/--clean option\n"),
+				progname);
+		exit_nicely(1);
+	}
+	opts->if_exists = if_exists;
+
 	if (opts->formatName)
 	{
 		switch (opts->formatName[0])
@@ -456,6 +466,7 @@ usage(const char *progname)
 	printf(_("  -x, --no-privileges          skip restoration of access privileges (grant/revoke)\n"));
 	printf(_("  -1, --single-transaction     restore as a single transaction\n"));
 	printf(_("  --disable-triggers           disable triggers during data-only restore\n"));
+	printf(_("  --if-exists                  use IF EXISTS when dropping objects\n"));
 	printf(_("  --no-data-for-failed-tables  do not restore data of tables that could not be\n"
 			 "                               created\n"));
 	printf(_("  --no-security-labels         do not restore security labels\n"));

*** a/doc/src/sgml/ref/pg_dump.sgml
--- b/doc/src/sgml/ref/pg_dump.sgml
***************
*** 650,655 ****
--- 650,665 ----
       </varlistentry>
  
       <varlistentry>
+       <term><option>--if-exists</option></term>
+       <listitem>
+        <para>
+         It uses conditional commands (with <literal>IF EXISTS</literal>
+         clause) for cleaning database schema.
+        </para>
+       </listitem>
+      </varlistentry>
+ 
+      <varlistentry>
        <term><option>--disable-dollar-quoting</></term>
        <listitem>
         <para>
*** a/doc/src/sgml/ref/pg_dumpall.sgml
--- b/doc/src/sgml/ref/pg_dumpall.sgml
***************
*** 301,306 ****
--- 301,316 ----
       </varlistentry>
  
       <varlistentry>
+       <term><option>--if-exists</option></term>
+       <listitem>
+        <para>
+         It uses conditional commands (with <literal>IF EXISTS</literal>
+         clause) for cleaning database schema.
+        </para>
+       </listitem>
+      </varlistentry>
+ 
+      <varlistentry>
        <term><option>--inserts</option></term>
        <listitem>
         <para>
*** a/doc/src/sgml/ref/pg_restore.sgml
--- b/doc/src/sgml/ref/pg_restore.sgml
***************
*** 490,495 ****
--- 490,505 ----
       </varlistentry>
  
       <varlistentry>
+       <term><option>--if-exists</option></term>
+       <listitem>
+        <para>
+         It uses conditional commands (with <literal>IF EXISTS</literal>
+         clause) for cleaning database schema.
+        </para>
+       </listitem>
+      </varlistentry>
+ 
+      <varlistentry>
        <term><option>--no-data-for-failed-tables</option></term>
        <listitem>
         <para>
*** a/src/bin/pg_dump/pg_backup.h
--- b/src/bin/pg_dump/pg_backup.h
***************
*** 113,118 ****
--- 113,119 ----
  	char	   *superuser;		/* Username to use as superuser */
  	char	   *use_role;		/* Issue SET ROLE to this */
  	int			dropSchema;
+ 	int			if_exists;
  	const char *filename;
  	int			dataOnly;
  	int			schemaOnly;
*** a/src/bin/pg_dump/pg_backup_archiver.c
--- b/src/bin/pg_dump/pg_backup_archiver.c
***************
*** 413,420 ****
  				/* Select owner and schema as necessary */
  				_becomeOwner(AH, te);
  				_selectOutputSchema(AH, te->namespace);
! 				/* Drop it */
! 				ahprintf(AH, "%s", te->dropStmt);
  			}
  		}
  
--- 413,493 ----
  				/* Select owner and schema as necessary */
  				_becomeOwner(AH, te);
  				_selectOutputSchema(AH, te->namespace);
! 
! 				if (*te->dropStmt != '\0')
! 				{
! 					/* Inject IF EXISTS clause to DROP part when it is required. */
! 					if (ropt->if_exists)
! 					{
! 						char buffer[40];
! 						char *mark;
! 						char *dropStmt = te->dropStmt;
! 						PQExpBuffer ftStmt = createPQExpBuffer();
! 
! 						/* ALTER TABLE should be enahnced to ALTER TABLE IF EXISTS */
! 						if (strncmp(dropStmt, "ALTER TABLE", 11) == 0)
! 						{
! 							/*
! 							 * Prepare fault tolerant statement, but
! 							 * ensure unique IF EXISTS option.
! 							 */
! 							if (strncmp(dropStmt + 11, " IF EXISTS", 10) != 0)
! 							{
! 								appendPQExpBuffer(ftStmt, "ALTER TABLE IF EXISTS");
! 								dropStmt = dropStmt + 11;
! 							}
! 						}
! 
! 						/*
! 						 * Descriptor string (te-desc) should not be same as object
! 						 * specifier for DROP STATEMENT. The DROP DEFAULT has not
! 						 * IF EXISTS clause - has not sense.
! 						 */
! 						if (strcmp(te->desc, "DEFAULT") != 0)
! 						{
! 							if (strcmp(te->desc, "CONSTRAINT") == 0 ||
! 									 strcmp(te->desc, "CHECK CONSTRAINT") == 0 ||
! 									 strcmp(te->desc, "FK CONSTRAINT") == 0)
! 								strcpy(buffer, "DROP CONSTRAINT");
! 							else
! 								snprintf(buffer, sizeof(buffer), "DROP %s",
! 													 te->desc);
! 
! 							mark = strstr(dropStmt, buffer);
! 						}
! 						else
! 							mark = NULL;
! 
! 						if (mark != NULL)
! 						{
! 							size_t l = strlen(buffer);
! 
! 							/*
! 							 * Insert IF EXISTS clause when it is not
! 							 * used yet.
! 							 */
! 							if (strncmp(mark + l, " IF EXISTS", 10) != 0)
! 							{
! 								*mark = '\0';
! 
! 								appendPQExpBuffer(ftStmt, "%s%s IF EXISTS%s",
! 													    dropStmt,
! 													    buffer,
! 													    mark + l);
! 							}
! 							else
! 								appendPQExpBuffer(ftStmt, "%s", dropStmt);
! 						}
! 						else
! 							appendPQExpBuffer(ftStmt, "%s", dropStmt);
! 
! 						ahprintf(AH, "%s", ftStmt->data);
! 
! 						destroyPQExpBuffer(ftStmt);
! 					}
! 					else
! 						ahprintf(AH, "%s", te->dropStmt);
! 				}
  			}
  		}
  
***************
*** 2942,2950 ****
  		strcmp(type, "OPERATOR CLASS") == 0 ||
  		strcmp(type, "OPERATOR FAMILY") == 0)
  	{
! 		/* Chop "DROP " off the front and make a modifiable copy */
! 		char	   *first = pg_strdup(te->dropStmt + 5);
! 		char	   *last;
  
  		/* point to last character in string */
  		last = first + strlen(first) - 1;
--- 3015,3053 ----
  		strcmp(type, "OPERATOR CLASS") == 0 ||
  		strcmp(type, "OPERATOR FAMILY") == 0)
  	{
! 		char	    *first;
! 		char	    *last;
! 
! 		/*
! 		 * Object description is based on dropStmt statement which may have
! 		 * IF EXISTS clause.  Thus we need to update an offset such that it
! 		 * won't be included in the object description.
! 		 */
! 		if (strstr(te->dropStmt, "IF EXISTS") != NULL)
! 		{
! 			char buffer[40];
! 			size_t   l;
! 
! 			/* Be sure, so IF EXISTS is used as DROP stmt option. */
! 			snprintf(buffer, sizeof(buffer), "DROP %s IF EXISTS", type);
! 
! 			l = strlen(buffer);
! 
! 			if (strncmp(te->dropStmt, buffer, l) == 0)
! 			{
! 				/* append command type to target type */
! 				appendPQExpBufferStr(buf, type);
! 
! 				/* skip first n chars, and create a modifiable copy */
! 				first = pg_strdup(te->dropStmt + l);
! 			}
! 			else
! 				/* DROP IF EXISTS pattern is not applicable on dropStmt */
! 				first = pg_strdup(te->dropStmt + 5);
! 		}
! 		else
! 			/* IF EXISTS clause was not used, simple solution */
! 			first = pg_strdup(te->dropStmt + 5);
  
  		/* point to last character in string */
  		last = first + strlen(first) - 1;
*** a/src/bin/pg_dump/pg_dump.c
--- b/src/bin/pg_dump/pg_dump.c
***************
*** 136,141 ****
--- 136,142 ----
  static int	disable_dollar_quoting = 0;
  static int	dump_inserts = 0;
  static int	column_inserts = 0;
+ static int	if_exists = 0;
  static int	no_security_labels = 0;
  static int	no_synchronized_snapshots = 0;
  static int	no_unlogged_table_data = 0;
***************
*** 349,354 ****
--- 350,356 ----
  		{"disable-dollar-quoting", no_argument, &disable_dollar_quoting, 1},
  		{"disable-triggers", no_argument, &disable_triggers, 1},
  		{"exclude-table-data", required_argument, NULL, 4},
+ 		{"if-exists", no_argument, &if_exists, 1},
  		{"inserts", no_argument, &dump_inserts, 1},
  		{"lock-wait-timeout", required_argument, NULL, 2},
  		{"no-tablespaces", no_argument, &outputNoTablespaces, 1},
***************
*** 577,582 ****
--- 579,587 ----
  		exit_nicely(1);
  	}
  
+ 	if (if_exists && !outputClean)
+ 		exit_horribly(NULL, "option --if-exists requires -c/--clean option\n");
+ 
  	/* Identify archive format to emit */
  	archiveFormat = parseArchiveFormat(format, &archiveMode);
  
***************
*** 809,814 ****
--- 814,820 ----
  	ropt->dropSchema = outputClean;
  	ropt->dataOnly = dataOnly;
  	ropt->schemaOnly = schemaOnly;
+ 	ropt->if_exists = if_exists;
  	ropt->dumpSections = dumpSections;
  	ropt->aclsSkip = aclsSkip;
  	ropt->superuser = outputSuperuser;
***************
*** 890,895 ****
--- 896,902 ----
  	printf(_("  --disable-dollar-quoting     disable dollar quoting, use SQL standard quoting\n"));
  	printf(_("  --disable-triggers           disable triggers during data-only restore\n"));
  	printf(_("  --exclude-table-data=TABLE   do NOT dump data for the named table(s)\n"));
+ 	printf(_("  --if-exists                  use IF EXISTS when dropping objects\n"));
  	printf(_("  --inserts                    dump data as INSERT commands, rather than COPY\n"));
  	printf(_("  --no-security-labels         do not dump security label assignments\n"));
  	printf(_("  --no-synchronized-snapshots  do not use synchronized snapshots in parallel jobs\n"));
*** a/src/bin/pg_dump/pg_dumpall.c
--- b/src/bin/pg_dump/pg_dumpall.c
***************
*** 73,78 ****
--- 73,79 ----
  static int	column_inserts = 0;
  static int	disable_dollar_quoting = 0;
  static int	disable_triggers = 0;
+ static int	if_exists = 0;
  static int	inserts = 0;
  static int	no_tablespaces = 0;
  static int	use_setsessauth = 0;
***************
*** 119,124 ****
--- 120,126 ----
  		{"column-inserts", no_argument, &column_inserts, 1},
  		{"disable-dollar-quoting", no_argument, &disable_dollar_quoting, 1},
  		{"disable-triggers", no_argument, &disable_triggers, 1},
+ 		{"if-exists", no_argument, &if_exists, 1},
  		{"inserts", no_argument, &inserts, 1},
  		{"lock-wait-timeout", required_argument, NULL, 2},
  		{"no-tablespaces", no_argument, &no_tablespaces, 1},
***************
*** 352,357 ****
--- 354,361 ----
  		appendPQExpBufferStr(pgdumpopts, " --disable-dollar-quoting");
  	if (disable_triggers)
  		appendPQExpBufferStr(pgdumpopts, " --disable-triggers");
+ 	if (if_exists)
+ 		appendPQExpBufferStr(pgdumpopts, " --if-exists");
  	if (inserts)
  		appendPQExpBufferStr(pgdumpopts, " --inserts");
  	if (no_tablespaces)
***************
*** 564,569 ****
--- 568,574 ----
  	printf(_("  --column-inserts             dump data as INSERT commands with column names\n"));
  	printf(_("  --disable-dollar-quoting     disable dollar quoting, use SQL standard quoting\n"));
  	printf(_("  --disable-triggers           disable triggers during data-only restore\n"));
+ 	printf(_("  --if-exists                  use IF EXISTS when dropping objects\n"));
  	printf(_("  --inserts                    dump data as INSERT commands, rather than COPY\n"));
  	printf(_("  --no-security-labels         do not dump security label assignments\n"));
  	printf(_("  --no-tablespaces             do not dump tablespace assignments\n"));
*** a/src/bin/pg_dump/pg_restore.c
--- b/src/bin/pg_dump/pg_restore.c
***************
*** 76,81 ****
--- 76,82 ----
  	Archive    *AH;
  	char	   *inputFileSpec;
  	static int	disable_triggers = 0;
+ 	static int	if_exists = 0;
  	static int	no_data_for_failed_tables = 0;
  	static int	outputNoTablespaces = 0;
  	static int	use_setsessauth = 0;
***************
*** 116,121 ****
--- 117,123 ----
  		 * the following options don't have an equivalent short option letter
  		 */
  		{"disable-triggers", no_argument, &disable_triggers, 1},
+ 		{"if-exists", no_argument, &if_exists, 1},
  		{"no-data-for-failed-tables", no_argument, &no_data_for_failed_tables, 1},
  		{"no-tablespaces", no_argument, &outputNoTablespaces, 1},
  		{"role", required_argument, NULL, 2},
***************
*** 342,347 ****
--- 344,357 ----
  	opts->use_setsessauth = use_setsessauth;
  	opts->no_security_labels = no_security_labels;
  
+ 	if (if_exists && !opts->dropSchema)
+ 	{
+ 		fprintf(stderr, _("%s: option --if-exists requires -c/--clean option\n"),
+ 				progname);
+ 		exit_nicely(1);
+ 	}
+ 	opts->if_exists = if_exists;
+ 
  	if (opts->formatName)
  	{
  		switch (opts->formatName[0])
***************
*** 456,461 ****
--- 466,472 ----
  	printf(_("  -x, --no-privileges          skip restoration of access privileges (grant/revoke)\n"));
  	printf(_("  -1, --single-transaction     restore as a single transaction\n"));
  	printf(_("  --disable-triggers           disable triggers during data-only restore\n"));
+ 	printf(_("  --if-exists                  use IF EXISTS when dropping objects\n"));
  	printf(_("  --no-data-for-failed-tables  do not restore data of tables that could not be\n"
  			 "                               created\n"));
  	printf(_("  --no-security-labels         do not restore security labels\n"));

commit e72e3ae9003d2c8eea0e687122a2f31d21674b81
Author: Pavel Stehule <pavel.stehule@gooddata.com>
Date:   Thu Jan 30 11:28:40 2014 +0100

    fix comment

diff --git a/doc/src/sgml/ref/pg_dump.sgml b/doc/src/sgml/ref/pg_dump.sgml
new file mode 100644
index 8d45f24..c39767b
*** a/doc/src/sgml/ref/pg_dump.sgml
--- b/doc/src/sgml/ref/pg_dump.sgml
*************** PostgreSQL documentation
*** 650,655 ****
--- 650,665 ----
       </varlistentry>
  
       <varlistentry>
+       <term><option>--if-exists</option></term>
+       <listitem>
+        <para>
+         It uses conditional commands (with <literal>IF EXISTS</literal>
+         clause) for cleaning database schema.
+        </para>
+       </listitem>
+      </varlistentry>
+ 
+      <varlistentry>
        <term><option>--disable-dollar-quoting</></term>
        <listitem>
         <para>
diff --git a/doc/src/sgml/ref/pg_dumpall.sgml b/doc/src/sgml/ref/pg_dumpall.sgml
new file mode 100644
index 5c6a101..ba6583d
*** a/doc/src/sgml/ref/pg_dumpall.sgml
--- b/doc/src/sgml/ref/pg_dumpall.sgml
*************** PostgreSQL documentation
*** 301,306 ****
--- 301,316 ----
       </varlistentry>
  
       <varlistentry>
+       <term><option>--if-exists</option></term>
+       <listitem>
+        <para>
+         It uses conditional commands (with <literal>IF EXISTS</literal>
+         clause) for cleaning database schema.
+        </para>
+       </listitem>
+      </varlistentry>
+ 
+      <varlistentry>
        <term><option>--inserts</option></term>
        <listitem>
         <para>
diff --git a/doc/src/sgml/ref/pg_restore.sgml b/doc/src/sgml/ref/pg_restore.sgml
new file mode 100644
index 717da42..55326d5
*** a/doc/src/sgml/ref/pg_restore.sgml
--- b/doc/src/sgml/ref/pg_restore.sgml
***************
*** 490,495 ****
--- 490,505 ----
       </varlistentry>
  
       <varlistentry>
+       <term><option>--if-exists</option></term>
+       <listitem>
+        <para>
+         It uses conditional commands (with <literal>IF EXISTS</literal>
+         clause) for cleaning database schema.
+        </para>
+       </listitem>
+      </varlistentry>
+ 
+      <varlistentry>
        <term><option>--no-data-for-failed-tables</option></term>
        <listitem>
         <para>
diff --git a/src/bin/pg_dump/pg_backup.h b/src/bin/pg_dump/pg_backup.h
new file mode 100644
index 6927968..83f7216
*** a/src/bin/pg_dump/pg_backup.h
--- b/src/bin/pg_dump/pg_backup.h
*************** typedef struct _restoreOptions
*** 113,118 ****
--- 113,119 ----
  	char	   *superuser;		/* Username to use as superuser */
  	char	   *use_role;		/* Issue SET ROLE to this */
  	int			dropSchema;
+ 	int			if_exists;
  	const char *filename;
  	int			dataOnly;
  	int			schemaOnly;
diff --git a/src/bin/pg_dump/pg_backup_archiver.c b/src/bin/pg_dump/pg_backup_archiver.c
new file mode 100644
index 7fc0288..a7061d3
*** a/src/bin/pg_dump/pg_backup_archiver.c
--- b/src/bin/pg_dump/pg_backup_archiver.c
*************** RestoreArchive(Archive *AHX)
*** 413,420 ****
  				/* Select owner and schema as necessary */
  				_becomeOwner(AH, te);
  				_selectOutputSchema(AH, te->namespace);
! 				/* Drop it */
! 				ahprintf(AH, "%s", te->dropStmt);
  			}
  		}
  
--- 413,496 ----
  				/* Select owner and schema as necessary */
  				_becomeOwner(AH, te);
  				_selectOutputSchema(AH, te->namespace);
! 
! 				if (*te->dropStmt != '\0')
! 				{
! 					/* Inject IF EXISTS clause to DROP part when it is required. */
! 					if (ropt->if_exists)
! 					{
! 						char buffer[40];
! 						char *mark;
! 						char *dropStmt = te->dropStmt;
! 						PQExpBuffer ftStmt = createPQExpBuffer();
! 
! 						/* ALTER TABLE should be enahnced to ALTER TABLE IF EXISTS */
! 						if (strncmp(dropStmt, "ALTER TABLE", 11) == 0)
! 						{
! 							/*
! 							 * Prepare fault tolerant statement, but
! 							 * ensure unique IF EXISTS option.
! 							 */
! 							if (strncmp(dropStmt + 11, " IF EXISTS", 10) != 0)
! 							{
! 								appendPQExpBuffer(ftStmt, "ALTER TABLE IF EXISTS");
! 								dropStmt = dropStmt + 11;
! 							}
! 						}
! 
! 						/*
! 						 * A content of te->desc is usually substring of DROP STATEMENT
! 						 * with one related exception - CONSTRAINTs.
! 						 *
! 						 * Independent to previous sentence - ALTER TABLE ALTER COLUMN
! 						 * DROP DEFAULT doesn't support IF EXISTS - and therefore it
! 						 * should not be injected.
! 						 */
! 						if (strcmp(te->desc, "DEFAULT") != 0)
! 						{
! 							if (strcmp(te->desc, "CONSTRAINT") == 0 ||
! 									 strcmp(te->desc, "CHECK CONSTRAINT") == 0 ||
! 									 strcmp(te->desc, "FK CONSTRAINT") == 0)
! 								strcpy(buffer, "DROP CONSTRAINT");
! 							else
! 								snprintf(buffer, sizeof(buffer), "DROP %s",
! 													 te->desc);
! 
! 							mark = strstr(dropStmt, buffer);
! 						}
! 						else
! 							mark = NULL;
! 
! 						if (mark != NULL)
! 						{
! 							size_t l = strlen(buffer);
! 
! 							/*
! 							 * Insert IF EXISTS clause when it is not
! 							 * used yet.
! 							 */
! 							if (strncmp(mark + l, " IF EXISTS", 10) != 0)
! 							{
! 								*mark = '\0';
! 
! 								appendPQExpBuffer(ftStmt, "%s%s IF EXISTS%s",
! 													    dropStmt,
! 													    buffer,
! 													    mark + l);
! 							}
! 							else
! 								appendPQExpBuffer(ftStmt, "%s", dropStmt);
! 						}
! 						else
! 							appendPQExpBuffer(ftStmt, "%s", dropStmt);
! 
! 						ahprintf(AH, "%s", ftStmt->data);
! 
! 						destroyPQExpBuffer(ftStmt);
! 					}
! 					else
! 						ahprintf(AH, "%s", te->dropStmt);
! 				}
  			}
  		}
  
*************** _getObjectDescription(PQExpBuffer buf, T
*** 2942,2950 ****
  		strcmp(type, "OPERATOR CLASS") == 0 ||
  		strcmp(type, "OPERATOR FAMILY") == 0)
  	{
! 		/* Chop "DROP " off the front and make a modifiable copy */
! 		char	   *first = pg_strdup(te->dropStmt + 5);
! 		char	   *last;
  
  		/* point to last character in string */
  		last = first + strlen(first) - 1;
--- 3018,3056 ----
  		strcmp(type, "OPERATOR CLASS") == 0 ||
  		strcmp(type, "OPERATOR FAMILY") == 0)
  	{
! 		char	    *first;
! 		char	    *last;
! 
! 		/*
! 		 * Object description is based on dropStmt statement which may have
! 		 * IF EXISTS clause.  Thus we need to update an offset such that it
! 		 * won't be included in the object description.
! 		 */
! 		if (strstr(te->dropStmt, "IF EXISTS") != NULL)
! 		{
! 			char buffer[40];
! 			size_t   l;
! 
! 			/* Be sure, so IF EXISTS is used as DROP stmt option. */
! 			snprintf(buffer, sizeof(buffer), "DROP %s IF EXISTS", type);
! 
! 			l = strlen(buffer);
! 
! 			if (strncmp(te->dropStmt, buffer, l) == 0)
! 			{
! 				/* append command type to target type */
! 				appendPQExpBufferStr(buf, type);
! 
! 				/* skip first n chars, and create a modifiable copy */
! 				first = pg_strdup(te->dropStmt + l);
! 			}
! 			else
! 				/* DROP IF EXISTS pattern is not applicable on dropStmt */
! 				first = pg_strdup(te->dropStmt + 5);
! 		}
! 		else
! 			/* IF EXISTS clause was not used, simple solution */
! 			first = pg_strdup(te->dropStmt + 5);
  
  		/* point to last character in string */
  		last = first + strlen(first) - 1;
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
new file mode 100644
index ebbb5b7..2f4f3a1
*** a/src/bin/pg_dump/pg_dump.c
--- b/src/bin/pg_dump/pg_dump.c
*************** static int	binary_upgrade = 0;
*** 136,141 ****
--- 136,142 ----
  static int	disable_dollar_quoting = 0;
  static int	dump_inserts = 0;
  static int	column_inserts = 0;
+ static int	if_exists = 0;
  static int	no_security_labels = 0;
  static int	no_synchronized_snapshots = 0;
  static int	no_unlogged_table_data = 0;
*************** main(int argc, char **argv)
*** 349,354 ****
--- 350,356 ----
  		{"disable-dollar-quoting", no_argument, &disable_dollar_quoting, 1},
  		{"disable-triggers", no_argument, &disable_triggers, 1},
  		{"exclude-table-data", required_argument, NULL, 4},
+ 		{"if-exists", no_argument, &if_exists, 1},
  		{"inserts", no_argument, &dump_inserts, 1},
  		{"lock-wait-timeout", required_argument, NULL, 2},
  		{"no-tablespaces", no_argument, &outputNoTablespaces, 1},
*************** main(int argc, char **argv)
*** 577,582 ****
--- 579,587 ----
  		exit_nicely(1);
  	}
  
+ 	if (if_exists && !outputClean)
+ 		exit_horribly(NULL, "option --if-exists requires -c/--clean option\n");
+ 
  	/* Identify archive format to emit */
  	archiveFormat = parseArchiveFormat(format, &archiveMode);
  
*************** main(int argc, char **argv)
*** 809,814 ****
--- 814,820 ----
  	ropt->dropSchema = outputClean;
  	ropt->dataOnly = dataOnly;
  	ropt->schemaOnly = schemaOnly;
+ 	ropt->if_exists = if_exists;
  	ropt->dumpSections = dumpSections;
  	ropt->aclsSkip = aclsSkip;
  	ropt->superuser = outputSuperuser;
*************** help(const char *progname)
*** 890,895 ****
--- 896,902 ----
  	printf(_("  --disable-dollar-quoting     disable dollar quoting, use SQL standard quoting\n"));
  	printf(_("  --disable-triggers           disable triggers during data-only restore\n"));
  	printf(_("  --exclude-table-data=TABLE   do NOT dump data for the named table(s)\n"));
+ 	printf(_("  --if-exists                  use IF EXISTS when dropping objects\n"));
  	printf(_("  --inserts                    dump data as INSERT commands, rather than COPY\n"));
  	printf(_("  --no-security-labels         do not dump security label assignments\n"));
  	printf(_("  --no-synchronized-snapshots  do not use synchronized snapshots in parallel jobs\n"));
diff --git a/src/bin/pg_dump/pg_dumpall.c b/src/bin/pg_dump/pg_dumpall.c
new file mode 100644
index 193c1a0..335fdde
*** a/src/bin/pg_dump/pg_dumpall.c
--- b/src/bin/pg_dump/pg_dumpall.c
*************** static int	binary_upgrade = 0;
*** 73,78 ****
--- 73,79 ----
  static int	column_inserts = 0;
  static int	disable_dollar_quoting = 0;
  static int	disable_triggers = 0;
+ static int	if_exists = 0;
  static int	inserts = 0;
  static int	no_tablespaces = 0;
  static int	use_setsessauth = 0;
*************** main(int argc, char *argv[])
*** 119,124 ****
--- 120,126 ----
  		{"column-inserts", no_argument, &column_inserts, 1},
  		{"disable-dollar-quoting", no_argument, &disable_dollar_quoting, 1},
  		{"disable-triggers", no_argument, &disable_triggers, 1},
+ 		{"if-exists", no_argument, &if_exists, 1},
  		{"inserts", no_argument, &inserts, 1},
  		{"lock-wait-timeout", required_argument, NULL, 2},
  		{"no-tablespaces", no_argument, &no_tablespaces, 1},
*************** main(int argc, char *argv[])
*** 352,357 ****
--- 354,361 ----
  		appendPQExpBufferStr(pgdumpopts, " --disable-dollar-quoting");
  	if (disable_triggers)
  		appendPQExpBufferStr(pgdumpopts, " --disable-triggers");
+ 	if (if_exists)
+ 		appendPQExpBufferStr(pgdumpopts, " --if-exists");
  	if (inserts)
  		appendPQExpBufferStr(pgdumpopts, " --inserts");
  	if (no_tablespaces)
*************** help(void)
*** 564,569 ****
--- 568,574 ----
  	printf(_("  --column-inserts             dump data as INSERT commands with column names\n"));
  	printf(_("  --disable-dollar-quoting     disable dollar quoting, use SQL standard quoting\n"));
  	printf(_("  --disable-triggers           disable triggers during data-only restore\n"));
+ 	printf(_("  --if-exists                  use IF EXISTS when dropping objects\n"));
  	printf(_("  --inserts                    dump data as INSERT commands, rather than COPY\n"));
  	printf(_("  --no-security-labels         do not dump security label assignments\n"));
  	printf(_("  --no-tablespaces             do not dump tablespace assignments\n"));
diff --git a/src/bin/pg_dump/pg_restore.c b/src/bin/pg_dump/pg_restore.c
new file mode 100644
index 2648003..74f9c2a
*** a/src/bin/pg_dump/pg_restore.c
--- b/src/bin/pg_dump/pg_restore.c
*************** main(int argc, char **argv)
*** 76,81 ****
--- 76,82 ----
  	Archive    *AH;
  	char	   *inputFileSpec;
  	static int	disable_triggers = 0;
+ 	static int	if_exists = 0;
  	static int	no_data_for_failed_tables = 0;
  	static int	outputNoTablespaces = 0;
  	static int	use_setsessauth = 0;
*************** main(int argc, char **argv)
*** 116,121 ****
--- 117,123 ----
  		 * the following options don't have an equivalent short option letter
  		 */
  		{"disable-triggers", no_argument, &disable_triggers, 1},
+ 		{"if-exists", no_argument, &if_exists, 1},
  		{"no-data-for-failed-tables", no_argument, &no_data_for_failed_tables, 1},
  		{"no-tablespaces", no_argument, &outputNoTablespaces, 1},
  		{"role", required_argument, NULL, 2},
*************** main(int argc, char **argv)
*** 342,347 ****
--- 344,357 ----
  	opts->use_setsessauth = use_setsessauth;
  	opts->no_security_labels = no_security_labels;
  
+ 	if (if_exists && !opts->dropSchema)
+ 	{
+ 		fprintf(stderr, _("%s: option --if-exists requires -c/--clean option\n"),
+ 				progname);
+ 		exit_nicely(1);
+ 	}
+ 	opts->if_exists = if_exists;
+ 
  	if (opts->formatName)
  	{
  		switch (opts->formatName[0])
*************** usage(const char *progname)
*** 456,461 ****
--- 466,472 ----
  	printf(_("  -x, --no-privileges          skip restoration of access privileges (grant/revoke)\n"));
  	printf(_("  -1, --single-transaction     restore as a single transaction\n"));
  	printf(_("  --disable-triggers           disable triggers during data-only restore\n"));
+ 	printf(_("  --if-exists                  use IF EXISTS when dropping objects\n"));
  	printf(_("  --no-data-for-failed-tables  do not restore data of tables that could not be\n"
  			 "                               created\n"));
  	printf(_("  --no-security-labels         do not restore security labels\n"));

diff --git a/doc/src/sgml/ref/pg_dump.sgml b/doc/src/sgml/ref/pg_dump.sgml
index 8d45f24..c39767b 100644
--- a/doc/src/sgml/ref/pg_dump.sgml
+++ b/doc/src/sgml/ref/pg_dump.sgml
@@ -650,6 +650,16 @@ PostgreSQL documentation
      </varlistentry>
 
      <varlistentry>
+      <term><option>--if-exists</option></term>
+      <listitem>
+       <para>
+        It uses conditional commands (with <literal>IF EXISTS</literal>
+        clause) for cleaning database schema.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><option>--disable-dollar-quoting</></term>
       <listitem>
        <para>
diff --git a/doc/src/sgml/ref/pg_dumpall.sgml b/doc/src/sgml/ref/pg_dumpall.sgml
index 5c6a101..ba6583d 100644
--- a/doc/src/sgml/ref/pg_dumpall.sgml
+++ b/doc/src/sgml/ref/pg_dumpall.sgml
@@ -301,6 +301,16 @@ PostgreSQL documentation
      </varlistentry>
 
      <varlistentry>
+      <term><option>--if-exists</option></term>
+      <listitem>
+       <para>
+        It uses conditional commands (with <literal>IF EXISTS</literal>
+        clause) for cleaning database schema.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><option>--inserts</option></term>
       <listitem>
        <para>
diff --git a/doc/src/sgml/ref/pg_restore.sgml b/doc/src/sgml/ref/pg_restore.sgml
index 717da42..55326d5 100644
--- a/doc/src/sgml/ref/pg_restore.sgml
+++ b/doc/src/sgml/ref/pg_restore.sgml
@@ -490,6 +490,16 @@
      </varlistentry>
 
      <varlistentry>
+      <term><option>--if-exists</option></term>
+      <listitem>
+       <para>
+        It uses conditional commands (with <literal>IF EXISTS</literal>
+        clause) for cleaning database schema.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><option>--no-data-for-failed-tables</option></term>
       <listitem>
        <para>
diff --git a/src/bin/pg_dump/pg_backup.h b/src/bin/pg_dump/pg_backup.h
index 6927968..83f7216 100644
--- a/src/bin/pg_dump/pg_backup.h
+++ b/src/bin/pg_dump/pg_backup.h
@@ -113,6 +113,7 @@ typedef struct _restoreOptions
 	char	   *superuser;		/* Username to use as superuser */
 	char	   *use_role;		/* Issue SET ROLE to this */
 	int			dropSchema;
+	int			if_exists;
 	const char *filename;
 	int			dataOnly;
 	int			schemaOnly;
diff --git a/src/bin/pg_dump/pg_backup_archiver.c b/src/bin/pg_dump/pg_backup_archiver.c
index 7fc0288..c08a0d3 100644
--- a/src/bin/pg_dump/pg_backup_archiver.c
+++ b/src/bin/pg_dump/pg_backup_archiver.c
@@ -413,8 +413,84 @@ RestoreArchive(Archive *AHX)
 				/* Select owner and schema as necessary */
 				_becomeOwner(AH, te);
 				_selectOutputSchema(AH, te->namespace);
-				/* Drop it */
-				ahprintf(AH, "%s", te->dropStmt);
+
+				if (*te->dropStmt != '\0')
+				{
+					/* Inject IF EXISTS clause to DROP part when required. */
+					if (ropt->if_exists)
+					{
+						char buffer[40];
+						char *mark;
+						char *dropStmt = te->dropStmt;
+						PQExpBuffer ftStmt = createPQExpBuffer();
+
+						/*
+						 * Need to inject IF EXISTS clause after ALTER TABLE
+						 * part in ALTER TABLE .. DROP statement
+						 */
+						if (strncmp(dropStmt, "ALTER TABLE", 11) == 0)
+						{
+							/*
+							 * Prepare fault tolerant statement, but ensure
+							 * unique IF EXISTS option.
+							 */
+							if (strncmp(dropStmt + 11, " IF EXISTS", 10) != 0)
+							{
+								appendPQExpBuffer(ftStmt,
+												  "ALTER TABLE IF EXISTS");
+								dropStmt = dropStmt + 11;
+							}
+						}
+
+						/*
+						 * A content of te->desc is usually substring of a DROP
+						 * statement with one related exception - CONSTRAINTs.
+						 *
+						 * Independent to previous sentence, ALTER TABLE ..
+						 * ALTER COLUMN .. DROP DEFAULT statement does not
+						 * support IF EXISTS clause and therefore it should not
+						 * be injected.
+						 */
+						if (strcmp(te->desc, "DEFAULT") != 0)
+						{
+							if (strcmp(te->desc, "CONSTRAINT") == 0 ||
+								strcmp(te->desc, "CHECK CONSTRAINT") == 0 ||
+								strcmp(te->desc, "FK CONSTRAINT") == 0)
+								strcpy(buffer, "DROP CONSTRAINT");
+							else
+								snprintf(buffer, sizeof(buffer), "DROP %s",
+													 te->desc);
+
+							mark = strstr(dropStmt, buffer);
+						}
+						else
+							mark = NULL;
+
+						if (mark != NULL)
+						{
+							size_t l = strlen(buffer);
+
+							/* Inject IF EXISTS clause if not alredy present */
+							if (strncmp(mark + l, " IF EXISTS", 10) != 0)
+							{
+								*mark = '\0';
+
+								appendPQExpBuffer(ftStmt, "%s%s IF EXISTS%s",
+												  dropStmt, buffer, mark + l);
+							}
+							else
+								appendPQExpBuffer(ftStmt, "%s", dropStmt);
+						}
+						else
+							appendPQExpBuffer(ftStmt, "%s", dropStmt);
+
+						ahprintf(AH, "%s", ftStmt->data);
+
+						destroyPQExpBuffer(ftStmt);
+					}
+					else
+						ahprintf(AH, "%s", te->dropStmt);
+				}
 			}
 		}
 
@@ -2942,9 +3018,39 @@ _getObjectDescription(PQExpBuffer buf, TocEntry *te, ArchiveHandle *AH)
 		strcmp(type, "OPERATOR CLASS") == 0 ||
 		strcmp(type, "OPERATOR FAMILY") == 0)
 	{
-		/* Chop "DROP " off the front and make a modifiable copy */
-		char	   *first = pg_strdup(te->dropStmt + 5);
-		char	   *last;
+		char	    *first;
+		char	    *last;
+
+		/*
+		 * Object description is based on dropStmt statement which may have
+		 * IF EXISTS clause.  Thus we need to update an offset such that it
+		 * won't be included in the object description.
+		 */
+		if (strstr(te->dropStmt, "IF EXISTS") != NULL)
+		{
+			char buffer[40];
+			size_t   l;
+
+			/* Be sure, so IF EXISTS is used as DROP stmt option. */
+			snprintf(buffer, sizeof(buffer), "DROP %s IF EXISTS", type);
+
+			l = strlen(buffer);
+
+			if (strncmp(te->dropStmt, buffer, l) == 0)
+			{
+				/* append command type to target type */
+				appendPQExpBufferStr(buf, type);
+
+				/* skip first n chars, and create a modifiable copy */
+				first = pg_strdup(te->dropStmt + l);
+			}
+			else
+				/* DROP IF EXISTS pattern is not applicable on dropStmt */
+				first = pg_strdup(te->dropStmt + 5);
+		}
+		else
+			/* IF EXISTS clause was not used, simple solution */
+			first = pg_strdup(te->dropStmt + 5);
 
 		/* point to last character in string */
 		last = first + strlen(first) - 1;
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index ebbb5b7..2f4f3a1 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -136,6 +136,7 @@ static int	binary_upgrade = 0;
 static int	disable_dollar_quoting = 0;
 static int	dump_inserts = 0;
 static int	column_inserts = 0;
+static int	if_exists = 0;
 static int	no_security_labels = 0;
 static int	no_synchronized_snapshots = 0;
 static int	no_unlogged_table_data = 0;
@@ -349,6 +350,7 @@ main(int argc, char **argv)
 		{"disable-dollar-quoting", no_argument, &disable_dollar_quoting, 1},
 		{"disable-triggers", no_argument, &disable_triggers, 1},
 		{"exclude-table-data", required_argument, NULL, 4},
+		{"if-exists", no_argument, &if_exists, 1},
 		{"inserts", no_argument, &dump_inserts, 1},
 		{"lock-wait-timeout", required_argument, NULL, 2},
 		{"no-tablespaces", no_argument, &outputNoTablespaces, 1},
@@ -577,6 +579,9 @@ main(int argc, char **argv)
 		exit_nicely(1);
 	}
 
+	if (if_exists && !outputClean)
+		exit_horribly(NULL, "option --if-exists requires -c/--clean option\n");
+
 	/* Identify archive format to emit */
 	archiveFormat = parseArchiveFormat(format, &archiveMode);
 
@@ -809,6 +814,7 @@ main(int argc, char **argv)
 	ropt->dropSchema = outputClean;
 	ropt->dataOnly = dataOnly;
 	ropt->schemaOnly = schemaOnly;
+	ropt->if_exists = if_exists;
 	ropt->dumpSections = dumpSections;
 	ropt->aclsSkip = aclsSkip;
 	ropt->superuser = outputSuperuser;
@@ -890,6 +896,7 @@ help(const char *progname)
 	printf(_("  --disable-dollar-quoting     disable dollar quoting, use SQL standard quoting\n"));
 	printf(_("  --disable-triggers           disable triggers during data-only restore\n"));
 	printf(_("  --exclude-table-data=TABLE   do NOT dump data for the named table(s)\n"));
+	printf(_("  --if-exists                  use IF EXISTS when dropping objects\n"));
 	printf(_("  --inserts                    dump data as INSERT commands, rather than COPY\n"));
 	printf(_("  --no-security-labels         do not dump security label assignments\n"));
 	printf(_("  --no-synchronized-snapshots  do not use synchronized snapshots in parallel jobs\n"));
diff --git a/src/bin/pg_dump/pg_dumpall.c b/src/bin/pg_dump/pg_dumpall.c
index 193c1a0..335fdde 100644
--- a/src/bin/pg_dump/pg_dumpall.c
+++ b/src/bin/pg_dump/pg_dumpall.c
@@ -73,6 +73,7 @@ static int	binary_upgrade = 0;
 static int	column_inserts = 0;
 static int	disable_dollar_quoting = 0;
 static int	disable_triggers = 0;
+static int	if_exists = 0;
 static int	inserts = 0;
 static int	no_tablespaces = 0;
 static int	use_setsessauth = 0;
@@ -119,6 +120,7 @@ main(int argc, char *argv[])
 		{"column-inserts", no_argument, &column_inserts, 1},
 		{"disable-dollar-quoting", no_argument, &disable_dollar_quoting, 1},
 		{"disable-triggers", no_argument, &disable_triggers, 1},
+		{"if-exists", no_argument, &if_exists, 1},
 		{"inserts", no_argument, &inserts, 1},
 		{"lock-wait-timeout", required_argument, NULL, 2},
 		{"no-tablespaces", no_argument, &no_tablespaces, 1},
@@ -352,6 +354,8 @@ main(int argc, char *argv[])
 		appendPQExpBufferStr(pgdumpopts, " --disable-dollar-quoting");
 	if (disable_triggers)
 		appendPQExpBufferStr(pgdumpopts, " --disable-triggers");
+	if (if_exists)
+		appendPQExpBufferStr(pgdumpopts, " --if-exists");
 	if (inserts)
 		appendPQExpBufferStr(pgdumpopts, " --inserts");
 	if (no_tablespaces)
@@ -564,6 +568,7 @@ help(void)
 	printf(_("  --column-inserts             dump data as INSERT commands with column names\n"));
 	printf(_("  --disable-dollar-quoting     disable dollar quoting, use SQL standard quoting\n"));
 	printf(_("  --disable-triggers           disable triggers during data-only restore\n"));
+	printf(_("  --if-exists                  use IF EXISTS when dropping objects\n"));
 	printf(_("  --inserts                    dump data as INSERT commands, rather than COPY\n"));
 	printf(_("  --no-security-labels         do not dump security label assignments\n"));
 	printf(_("  --no-tablespaces             do not dump tablespace assignments\n"));
diff --git a/src/bin/pg_dump/pg_restore.c b/src/bin/pg_dump/pg_restore.c
index 2648003..74f9c2a 100644
--- a/src/bin/pg_dump/pg_restore.c
+++ b/src/bin/pg_dump/pg_restore.c
@@ -76,6 +76,7 @@ main(int argc, char **argv)
 	Archive    *AH;
 	char	   *inputFileSpec;
 	static int	disable_triggers = 0;
+	static int	if_exists = 0;
 	static int	no_data_for_failed_tables = 0;
 	static int	outputNoTablespaces = 0;
 	static int	use_setsessauth = 0;
@@ -116,6 +117,7 @@ main(int argc, char **argv)
 		 * the following options don't have an equivalent short option letter
 		 */
 		{"disable-triggers", no_argument, &disable_triggers, 1},
+		{"if-exists", no_argument, &if_exists, 1},
 		{"no-data-for-failed-tables", no_argument, &no_data_for_failed_tables, 1},
 		{"no-tablespaces", no_argument, &outputNoTablespaces, 1},
 		{"role", required_argument, NULL, 2},
@@ -342,6 +344,14 @@ main(int argc, char **argv)
 	opts->use_setsessauth = use_setsessauth;
 	opts->no_security_labels = no_security_labels;
 
+	if (if_exists && !opts->dropSchema)
+	{
+		fprintf(stderr, _("%s: option --if-exists requires -c/--clean option\n"),
+				progname);
+		exit_nicely(1);
+	}
+	opts->if_exists = if_exists;
+
 	if (opts->formatName)
 	{
 		switch (opts->formatName[0])
@@ -456,6 +466,7 @@ usage(const char *progname)
 	printf(_("  -x, --no-privileges          skip restoration of access privileges (grant/revoke)\n"));
 	printf(_("  -1, --single-transaction     restore as a single transaction\n"));
 	printf(_("  --disable-triggers           disable triggers during data-only restore\n"));
+	printf(_("  --if-exists                  use IF EXISTS when dropping objects\n"));
 	printf(_("  --no-data-for-failed-tables  do not restore data of tables that could not be\n"
 			 "                               created\n"));
 	printf(_("  --no-security-labels         do not restore security labels\n"));

commit 937830b60920a8fac84cd2adb24c3d1b5280b036
Author: Pavel Stehule <pavel.stehule@gooddata.com>
Date:   Tue Feb 18 14:25:40 2014 +0100

    reduced2

diff --git a/doc/src/sgml/ref/pg_dump.sgml b/doc/src/sgml/ref/pg_dump.sgml
index 8d45f24..c39767b 100644
--- a/doc/src/sgml/ref/pg_dump.sgml
+++ b/doc/src/sgml/ref/pg_dump.sgml
@@ -650,6 +650,16 @@ PostgreSQL documentation
      </varlistentry>
 
      <varlistentry>
+      <term><option>--if-exists</option></term>
+      <listitem>
+       <para>
+        It uses conditional commands (with <literal>IF EXISTS</literal>
+        clause) for cleaning database schema.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><option>--disable-dollar-quoting</></term>
       <listitem>
        <para>
diff --git a/doc/src/sgml/ref/pg_dumpall.sgml b/doc/src/sgml/ref/pg_dumpall.sgml
index 5c6a101..ba6583d 100644
--- a/doc/src/sgml/ref/pg_dumpall.sgml
+++ b/doc/src/sgml/ref/pg_dumpall.sgml
@@ -301,6 +301,16 @@ PostgreSQL documentation
      </varlistentry>
 
      <varlistentry>
+      <term><option>--if-exists</option></term>
+      <listitem>
+       <para>
+        It uses conditional commands (with <literal>IF EXISTS</literal>
+        clause) for cleaning database schema.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><option>--inserts</option></term>
       <listitem>
        <para>
diff --git a/doc/src/sgml/ref/pg_restore.sgml b/doc/src/sgml/ref/pg_restore.sgml
index 717da42..55326d5 100644
--- a/doc/src/sgml/ref/pg_restore.sgml
+++ b/doc/src/sgml/ref/pg_restore.sgml
@@ -490,6 +490,16 @@
      </varlistentry>
 
      <varlistentry>
+      <term><option>--if-exists</option></term>
+      <listitem>
+       <para>
+        It uses conditional commands (with <literal>IF EXISTS</literal>
+        clause) for cleaning database schema.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><option>--no-data-for-failed-tables</option></term>
       <listitem>
        <para>
diff --git a/src/bin/pg_dump/pg_backup.h b/src/bin/pg_dump/pg_backup.h
index 6927968..83f7216 100644
--- a/src/bin/pg_dump/pg_backup.h
+++ b/src/bin/pg_dump/pg_backup.h
@@ -113,6 +113,7 @@ typedef struct _restoreOptions
 	char	   *superuser;		/* Username to use as superuser */
 	char	   *use_role;		/* Issue SET ROLE to this */
 	int			dropSchema;
+	int			if_exists;
 	const char *filename;
 	int			dataOnly;
 	int			schemaOnly;
diff --git a/src/bin/pg_dump/pg_backup_archiver.c b/src/bin/pg_dump/pg_backup_archiver.c
index 2b36e45..f36caf2 100644
--- a/src/bin/pg_dump/pg_backup_archiver.c
+++ b/src/bin/pg_dump/pg_backup_archiver.c
@@ -413,8 +413,64 @@ RestoreArchive(Archive *AHX)
 				/* Select owner and schema as necessary */
 				_becomeOwner(AH, te);
 				_selectOutputSchema(AH, te->namespace);
-				/* Drop it */
-				ahprintf(AH, "%s", te->dropStmt);
+
+				if (*te->dropStmt != '\0')
+				{
+					/* Inject IF EXISTS clause to DROP part when required. */
+					if (ropt->if_exists)
+					{
+						char buffer[40];
+						char *mark;
+						char *dropStmt = te->dropStmt;
+						PQExpBuffer ftStmt = createPQExpBuffer();
+
+						/*
+						 * Need to inject IF EXISTS clause after ALTER TABLE
+						 * part in ALTER TABLE .. DROP statement
+						 */
+						if (strncmp(dropStmt, "ALTER TABLE", 11) == 0)
+						{
+							appendPQExpBuffer(ftStmt,
+											  "ALTER TABLE IF EXISTS");
+							dropStmt = dropStmt + 11;
+						}
+
+						/*
+						 * A content of te->desc is usually substring of a DROP
+						 * statement with one related exception - CONSTRAINTs.
+						 *
+						 * Independent to previous sentence, ALTER TABLE ..
+						 * ALTER COLUMN .. DROP DEFAULT statement does not
+						 * support IF EXISTS clause and therefore it should not
+						 * be injected.
+						 */
+						if (strcmp(te->desc, "DEFAULT") != 0)
+						{
+							if (strcmp(te->desc, "CONSTRAINT") == 0 ||
+								strcmp(te->desc, "CHECK CONSTRAINT") == 0 ||
+								strcmp(te->desc, "FK CONSTRAINT") == 0)
+								strcpy(buffer, "DROP CONSTRAINT");
+							else
+								snprintf(buffer, sizeof(buffer), "DROP %s",
+													 te->desc);
+
+							mark = strstr(dropStmt, buffer);
+							Assert(mark != NULL);
+
+							*mark = '\0';
+							appendPQExpBuffer(ftStmt, "%s%s IF EXISTS%s",
+										  dropStmt, buffer, mark + strlen(buffer));
+						}
+						else
+							appendPQExpBuffer(ftStmt, "%s", dropStmt);
+
+						ahprintf(AH, "%s", ftStmt->data);
+
+						destroyPQExpBuffer(ftStmt);
+					}
+					else
+						ahprintf(AH, "%s", te->dropStmt);
+				}
 			}
 		}
 
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 458a118..88ea556 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -136,6 +136,7 @@ static int	binary_upgrade = 0;
 static int	disable_dollar_quoting = 0;
 static int	dump_inserts = 0;
 static int	column_inserts = 0;
+static int	if_exists = 0;
 static int	no_security_labels = 0;
 static int	no_synchronized_snapshots = 0;
 static int	no_unlogged_table_data = 0;
@@ -349,6 +350,7 @@ main(int argc, char **argv)
 		{"disable-dollar-quoting", no_argument, &disable_dollar_quoting, 1},
 		{"disable-triggers", no_argument, &disable_triggers, 1},
 		{"exclude-table-data", required_argument, NULL, 4},
+		{"if-exists", no_argument, &if_exists, 1},
 		{"inserts", no_argument, &dump_inserts, 1},
 		{"lock-wait-timeout", required_argument, NULL, 2},
 		{"no-tablespaces", no_argument, &outputNoTablespaces, 1},
@@ -577,6 +579,9 @@ main(int argc, char **argv)
 		exit_nicely(1);
 	}
 
+	if (if_exists && !outputClean)
+		exit_horribly(NULL, "option --if-exists requires -c/--clean option\n");
+
 	/* Identify archive format to emit */
 	archiveFormat = parseArchiveFormat(format, &archiveMode);
 
@@ -809,6 +814,7 @@ main(int argc, char **argv)
 	ropt->dropSchema = outputClean;
 	ropt->dataOnly = dataOnly;
 	ropt->schemaOnly = schemaOnly;
+	ropt->if_exists = if_exists;
 	ropt->dumpSections = dumpSections;
 	ropt->aclsSkip = aclsSkip;
 	ropt->superuser = outputSuperuser;
@@ -890,6 +896,7 @@ help(const char *progname)
 	printf(_("  --disable-dollar-quoting     disable dollar quoting, use SQL standard quoting\n"));
 	printf(_("  --disable-triggers           disable triggers during data-only restore\n"));
 	printf(_("  --exclude-table-data=TABLE   do NOT dump data for the named table(s)\n"));
+	printf(_("  --if-exists                  use IF EXISTS when dropping objects\n"));
 	printf(_("  --inserts                    dump data as INSERT commands, rather than COPY\n"));
 	printf(_("  --no-security-labels         do not dump security label assignments\n"));
 	printf(_("  --no-synchronized-snapshots  do not use synchronized snapshots in parallel jobs\n"));
diff --git a/src/bin/pg_dump/pg_dumpall.c b/src/bin/pg_dump/pg_dumpall.c
index 193c1a0..335fdde 100644
--- a/src/bin/pg_dump/pg_dumpall.c
+++ b/src/bin/pg_dump/pg_dumpall.c
@@ -73,6 +73,7 @@ static int	binary_upgrade = 0;
 static int	column_inserts = 0;
 static int	disable_dollar_quoting = 0;
 static int	disable_triggers = 0;
+static int	if_exists = 0;
 static int	inserts = 0;
 static int	no_tablespaces = 0;
 static int	use_setsessauth = 0;
@@ -119,6 +120,7 @@ main(int argc, char *argv[])
 		{"column-inserts", no_argument, &column_inserts, 1},
 		{"disable-dollar-quoting", no_argument, &disable_dollar_quoting, 1},
 		{"disable-triggers", no_argument, &disable_triggers, 1},
+		{"if-exists", no_argument, &if_exists, 1},
 		{"inserts", no_argument, &inserts, 1},
 		{"lock-wait-timeout", required_argument, NULL, 2},
 		{"no-tablespaces", no_argument, &no_tablespaces, 1},
@@ -352,6 +354,8 @@ main(int argc, char *argv[])
 		appendPQExpBufferStr(pgdumpopts, " --disable-dollar-quoting");
 	if (disable_triggers)
 		appendPQExpBufferStr(pgdumpopts, " --disable-triggers");
+	if (if_exists)
+		appendPQExpBufferStr(pgdumpopts, " --if-exists");
 	if (inserts)
 		appendPQExpBufferStr(pgdumpopts, " --inserts");
 	if (no_tablespaces)
@@ -564,6 +568,7 @@ help(void)
 	printf(_("  --column-inserts             dump data as INSERT commands with column names\n"));
 	printf(_("  --disable-dollar-quoting     disable dollar quoting, use SQL standard quoting\n"));
 	printf(_("  --disable-triggers           disable triggers during data-only restore\n"));
+	printf(_("  --if-exists                  use IF EXISTS when dropping objects\n"));
 	printf(_("  --inserts                    dump data as INSERT commands, rather than COPY\n"));
 	printf(_("  --no-security-labels         do not dump security label assignments\n"));
 	printf(_("  --no-tablespaces             do not dump tablespace assignments\n"));
diff --git a/src/bin/pg_dump/pg_restore.c b/src/bin/pg_dump/pg_restore.c
index bb65253..f732027 100644
--- a/src/bin/pg_dump/pg_restore.c
+++ b/src/bin/pg_dump/pg_restore.c
@@ -76,6 +76,7 @@ main(int argc, char **argv)
 	Archive    *AH;
 	char	   *inputFileSpec;
 	static int	disable_triggers = 0;
+	static int	if_exists = 0;
 	static int	no_data_for_failed_tables = 0;
 	static int	outputNoTablespaces = 0;
 	static int	use_setsessauth = 0;
@@ -116,6 +117,7 @@ main(int argc, char **argv)
 		 * the following options don't have an equivalent short option letter
 		 */
 		{"disable-triggers", no_argument, &disable_triggers, 1},
+		{"if-exists", no_argument, &if_exists, 1},
 		{"no-data-for-failed-tables", no_argument, &no_data_for_failed_tables, 1},
 		{"no-tablespaces", no_argument, &outputNoTablespaces, 1},
 		{"role", required_argument, NULL, 2},
@@ -342,6 +344,14 @@ main(int argc, char **argv)
 	opts->use_setsessauth = use_setsessauth;
 	opts->no_security_labels = no_security_labels;
 
+	if (if_exists && !opts->dropSchema)
+	{
+		fprintf(stderr, _("%s: option --if-exists requires -c/--clean option\n"),
+				progname);
+		exit_nicely(1);
+	}
+	opts->if_exists = if_exists;
+
 	if (opts->formatName)
 	{
 		switch (opts->formatName[0])
@@ -456,6 +466,7 @@ usage(const char *progname)
 	printf(_("  -x, --no-privileges          skip restoration of access privileges (grant/revoke)\n"));
 	printf(_("  -1, --single-transaction     restore as a single transaction\n"));
 	printf(_("  --disable-triggers           disable triggers during data-only restore\n"));
+	printf(_("  --if-exists                  use IF EXISTS when dropping objects\n"));
 	printf(_("  --no-data-for-failed-tables  do not restore data of tables that could not be\n"
 			 "                               created\n"));
 	printf(_("  --no-security-labels         do not restore security labels\n"));

diff --git a/doc/src/sgml/ref/pg_dump.sgml b/doc/src/sgml/ref/pg_dump.sgml
index 40c69f0..1f0d4de 100644
--- a/doc/src/sgml/ref/pg_dump.sgml
+++ b/doc/src/sgml/ref/pg_dump.sgml
@@ -145,7 +145,8 @@ PostgreSQL documentation
        <para>
         Output commands to clean (drop)
         database objects prior to outputting the commands for creating them.
-        (Restore might generate some harmless error messages, if any objects
+        (Unless <option>--if-exists</> is also specified,
+        restore might generate some harmless error messages, if any objects
         were not present in the destination database.)
        </para>
 
@@ -650,6 +651,17 @@ PostgreSQL documentation
      </varlistentry>
 
      <varlistentry>
+      <term><option>--if-exists</option></term>
+      <listitem>
+       <para>
+        Use conditional commands (i.e. add an <literal>IF EXISTS</literal>
+        clause) when cleaning database objects.  This option is not valid
+        unless <option>--clean</> is also specified.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><option>--disable-dollar-quoting</></term>
       <listitem>
        <para>
diff --git a/doc/src/sgml/ref/pg_dumpall.sgml b/doc/src/sgml/ref/pg_dumpall.sgml
index f337939..fcf5f77 100644
--- a/doc/src/sgml/ref/pg_dumpall.sgml
+++ b/doc/src/sgml/ref/pg_dumpall.sgml
@@ -301,6 +301,17 @@ PostgreSQL documentation
      </varlistentry>
 
      <varlistentry>
+      <term><option>--if-exists</option></term>
+      <listitem>
+       <para>
+        Use conditional commands (i.e. add an <literal>IF EXISTS</literal>
+        clause) to clean databases and other objects.  This option is not valid
+        unless <option>--clean</> is also specified.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><option>--inserts</option></term>
       <listitem>
        <para>
diff --git a/doc/src/sgml/ref/pg_restore.sgml b/doc/src/sgml/ref/pg_restore.sgml
index cd60b25..4bc30ce 100644
--- a/doc/src/sgml/ref/pg_restore.sgml
+++ b/doc/src/sgml/ref/pg_restore.sgml
@@ -109,7 +109,8 @@
       <listitem>
        <para>
         Clean (drop) database objects before recreating them.
-        (This might generate some harmless error messages, if any objects
+        (Unless <option>--if-exists</> is used,
+        this might generate some harmless error messages, if any objects
         were not present in the destination database.)
        </para>
       </listitem>
@@ -490,6 +491,17 @@
      </varlistentry>
 
      <varlistentry>
+      <term><option>--if-exists</option></term>
+      <listitem>
+       <para>
+        Use conditional commands (i.e. add an <literal>IF EXISTS</literal>
+        clause) when cleaning database objects.  This option is not valid
+        unless <option>--clean</> is also specified.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><option>--no-data-for-failed-tables</option></term>
       <listitem>
        <para>
diff --git a/src/bin/pg_dump/pg_backup.h b/src/bin/pg_dump/pg_backup.h
index 6927968..83f7216 100644
--- a/src/bin/pg_dump/pg_backup.h
+++ b/src/bin/pg_dump/pg_backup.h
@@ -113,6 +113,7 @@ typedef struct _restoreOptions
 	char	   *superuser;		/* Username to use as superuser */
 	char	   *use_role;		/* Issue SET ROLE to this */
 	int			dropSchema;
+	int			if_exists;
 	const char *filename;
 	int			dataOnly;
 	int			schemaOnly;
diff --git a/src/bin/pg_dump/pg_backup_archiver.c b/src/bin/pg_dump/pg_backup_archiver.c
index 2b36e45..8395373 100644
--- a/src/bin/pg_dump/pg_backup_archiver.c
+++ b/src/bin/pg_dump/pg_backup_archiver.c
@@ -413,8 +413,76 @@ RestoreArchive(Archive *AHX)
 				/* Select owner and schema as necessary */
 				_becomeOwner(AH, te);
 				_selectOutputSchema(AH, te->namespace);
-				/* Drop it */
-				ahprintf(AH, "%s", te->dropStmt);
+
+				/*
+				 * Now emit the DROP command, if the object has one.  Note we
+				 * don't necessarily emit it verbatim; at this point we add an
+				 * appropriate IF EXISTS clause, if the user requested it.
+				 */
+				if (*te->dropStmt != '\0')
+				{
+					if (!ropt->if_exists)
+					{
+						/* No --if-exists?  Then just use the original */
+						ahprintf(AH, "%s", te->dropStmt);
+					}
+					else
+					{
+						char		buffer[40];
+						char	   *mark;
+						char	   *dropStmt = pg_strdup(te->dropStmt);
+						PQExpBuffer	ftStmt = createPQExpBuffer();
+
+						/*
+						 * Need to inject IF EXISTS clause after ALTER TABLE
+						 * part in ALTER TABLE .. DROP statement
+						 */
+						if (strncmp(dropStmt, "ALTER TABLE", 11) == 0)
+						{
+							appendPQExpBuffer(ftStmt,
+											  "ALTER TABLE IF EXISTS");
+							dropStmt = dropStmt + 11;
+						}
+
+						/*
+						 * ALTER TABLE..ALTER COLUMN..DROP DEFAULT does not
+						 * support the IF EXISTS clause, and therefore we
+						 * simply emit the original command for such objects.
+						 * For other objects, we need to extract the first part
+						 * of the DROP which includes the object type.  Most of
+						 * the time this matches te->desc, so search for that;
+						 * however for the different kinds of CONSTRAINTs, we
+						 * know to search for hardcoded "DROP CONSTRAINT"
+						 * instead.
+						 */
+						if (strcmp(te->desc, "DEFAULT") == 0)
+							appendPQExpBuffer(ftStmt, "%s", dropStmt);
+						else
+						{
+							if (strcmp(te->desc, "CONSTRAINT") == 0 ||
+								strcmp(te->desc, "CHECK CONSTRAINT") == 0 ||
+								strcmp(te->desc, "FK CONSTRAINT") == 0)
+								strcpy(buffer, "DROP CONSTRAINT");
+							else
+								snprintf(buffer, sizeof(buffer), "DROP %s",
+										 te->desc);
+
+							mark = strstr(dropStmt, buffer);
+							Assert(mark != NULL);
+
+							*mark = '\0';
+							appendPQExpBuffer(ftStmt, "%s%s IF EXISTS%s",
+											  dropStmt, buffer,
+											  mark + strlen(buffer));
+						}
+
+						ahprintf(AH, "%s", ftStmt->data);
+
+						destroyPQExpBuffer(ftStmt);
+
+						pg_free(dropStmt);
+					}
+				}
 			}
 		}
 
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 4fabc1d..80431fb 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -132,6 +132,7 @@ static int	binary_upgrade = 0;
 static int	disable_dollar_quoting = 0;
 static int	dump_inserts = 0;
 static int	column_inserts = 0;
+static int	if_exists = 0;
 static int	no_security_labels = 0;
 static int	no_synchronized_snapshots = 0;
 static int	no_unlogged_table_data = 0;
@@ -345,6 +346,7 @@ main(int argc, char **argv)
 		{"disable-dollar-quoting", no_argument, &disable_dollar_quoting, 1},
 		{"disable-triggers", no_argument, &disable_triggers, 1},
 		{"exclude-table-data", required_argument, NULL, 4},
+		{"if-exists", no_argument, &if_exists, 1},
 		{"inserts", no_argument, &dump_inserts, 1},
 		{"lock-wait-timeout", required_argument, NULL, 2},
 		{"no-tablespaces", no_argument, &outputNoTablespaces, 1},
@@ -573,6 +575,9 @@ main(int argc, char **argv)
 		exit_nicely(1);
 	}
 
+	if (if_exists && !outputClean)
+		exit_horribly(NULL, "option --if-exists requires -c/--clean option\n");
+
 	/* Identify archive format to emit */
 	archiveFormat = parseArchiveFormat(format, &archiveMode);
 
@@ -805,6 +810,7 @@ main(int argc, char **argv)
 	ropt->dropSchema = outputClean;
 	ropt->dataOnly = dataOnly;
 	ropt->schemaOnly = schemaOnly;
+	ropt->if_exists = if_exists;
 	ropt->dumpSections = dumpSections;
 	ropt->aclsSkip = aclsSkip;
 	ropt->superuser = outputSuperuser;
@@ -886,6 +892,7 @@ help(const char *progname)
 	printf(_("  --disable-dollar-quoting     disable dollar quoting, use SQL standard quoting\n"));
 	printf(_("  --disable-triggers           disable triggers during data-only restore\n"));
 	printf(_("  --exclude-table-data=TABLE   do NOT dump data for the named table(s)\n"));
+	printf(_("  --if-exists                  use IF EXISTS when dropping objects\n"));
 	printf(_("  --inserts                    dump data as INSERT commands, rather than COPY\n"));
 	printf(_("  --no-security-labels         do not dump security label assignments\n"));
 	printf(_("  --no-synchronized-snapshots  do not use synchronized snapshots in parallel jobs\n"));
diff --git a/src/bin/pg_dump/pg_dumpall.c b/src/bin/pg_dump/pg_dumpall.c
index 193c1a0..335fdde 100644
--- a/src/bin/pg_dump/pg_dumpall.c
+++ b/src/bin/pg_dump/pg_dumpall.c
@@ -73,6 +73,7 @@ static int	binary_upgrade = 0;
 static int	column_inserts = 0;
 static int	disable_dollar_quoting = 0;
 static int	disable_triggers = 0;
+static int	if_exists = 0;
 static int	inserts = 0;
 static int	no_tablespaces = 0;
 static int	use_setsessauth = 0;
@@ -119,6 +120,7 @@ main(int argc, char *argv[])
 		{"column-inserts", no_argument, &column_inserts, 1},
 		{"disable-dollar-quoting", no_argument, &disable_dollar_quoting, 1},
 		{"disable-triggers", no_argument, &disable_triggers, 1},
+		{"if-exists", no_argument, &if_exists, 1},
 		{"inserts", no_argument, &inserts, 1},
 		{"lock-wait-timeout", required_argument, NULL, 2},
 		{"no-tablespaces", no_argument, &no_tablespaces, 1},
@@ -352,6 +354,8 @@ main(int argc, char *argv[])
 		appendPQExpBufferStr(pgdumpopts, " --disable-dollar-quoting");
 	if (disable_triggers)
 		appendPQExpBufferStr(pgdumpopts, " --disable-triggers");
+	if (if_exists)
+		appendPQExpBufferStr(pgdumpopts, " --if-exists");
 	if (inserts)
 		appendPQExpBufferStr(pgdumpopts, " --inserts");
 	if (no_tablespaces)
@@ -564,6 +568,7 @@ help(void)
 	printf(_("  --column-inserts             dump data as INSERT commands with column names\n"));
 	printf(_("  --disable-dollar-quoting     disable dollar quoting, use SQL standard quoting\n"));
 	printf(_("  --disable-triggers           disable triggers during data-only restore\n"));
+	printf(_("  --if-exists                  use IF EXISTS when dropping objects\n"));
 	printf(_("  --inserts                    dump data as INSERT commands, rather than COPY\n"));
 	printf(_("  --no-security-labels         do not dump security label assignments\n"));
 	printf(_("  --no-tablespaces             do not dump tablespace assignments\n"));
diff --git a/src/bin/pg_dump/pg_restore.c b/src/bin/pg_dump/pg_restore.c
index df9477b..f7f3f51 100644
--- a/src/bin/pg_dump/pg_restore.c
+++ b/src/bin/pg_dump/pg_restore.c
@@ -70,6 +70,7 @@ main(int argc, char **argv)
 	Archive    *AH;
 	char	   *inputFileSpec;
 	static int	disable_triggers = 0;
+	static int	if_exists = 0;
 	static int	no_data_for_failed_tables = 0;
 	static int	outputNoTablespaces = 0;
 	static int	use_setsessauth = 0;
@@ -110,6 +111,7 @@ main(int argc, char **argv)
 		 * the following options don't have an equivalent short option letter
 		 */
 		{"disable-triggers", no_argument, &disable_triggers, 1},
+		{"if-exists", no_argument, &if_exists, 1},
 		{"no-data-for-failed-tables", no_argument, &no_data_for_failed_tables, 1},
 		{"no-tablespaces", no_argument, &outputNoTablespaces, 1},
 		{"role", required_argument, NULL, 2},
@@ -336,6 +338,14 @@ main(int argc, char **argv)
 	opts->use_setsessauth = use_setsessauth;
 	opts->no_security_labels = no_security_labels;
 
+	if (if_exists && !opts->dropSchema)
+	{
+		fprintf(stderr, _("%s: option --if-exists requires -c/--clean option\n"),
+				progname);
+		exit_nicely(1);
+	}
+	opts->if_exists = if_exists;
+
 	if (opts->formatName)
 	{
 		switch (opts->formatName[0])
@@ -450,6 +460,7 @@ usage(const char *progname)
 	printf(_("  -x, --no-privileges          skip restoration of access privileges (grant/revoke)\n"));
 	printf(_("  -1, --single-transaction     restore as a single transaction\n"));
 	printf(_("  --disable-triggers           disable triggers during data-only restore\n"));
+	printf(_("  --if-exists                  use IF EXISTS when dropping objects\n"));
 	printf(_("  --no-data-for-failed-tables  do not restore data of tables that could not be\n"
 			 "                               created\n"));
 	printf(_("  --no-security-labels         do not restore security labels\n"));

commit 3e2e9baa3b5e708b4014b18cbedd2e6b1fc095a5
Author: root <root@nemesis.(none)>
Date:   Fri Feb 28 23:31:32 2014 +0100

    pg_dumpall --if-exists fix

diff --git a/doc/src/sgml/ref/pg_dump.sgml b/doc/src/sgml/ref/pg_dump.sgml
index 40c69f0..1f0d4de 100644
--- a/doc/src/sgml/ref/pg_dump.sgml
+++ b/doc/src/sgml/ref/pg_dump.sgml
@@ -145,7 +145,8 @@ PostgreSQL documentation
        <para>
         Output commands to clean (drop)
         database objects prior to outputting the commands for creating them.
-        (Restore might generate some harmless error messages, if any objects
+        (Unless <option>--if-exists</> is also specified,
+        restore might generate some harmless error messages, if any objects
         were not present in the destination database.)
        </para>
 
@@ -650,6 +651,17 @@ PostgreSQL documentation
      </varlistentry>
 
      <varlistentry>
+      <term><option>--if-exists</option></term>
+      <listitem>
+       <para>
+        Use conditional commands (i.e. add an <literal>IF EXISTS</literal>
+        clause) when cleaning database objects.  This option is not valid
+        unless <option>--clean</> is also specified.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><option>--disable-dollar-quoting</></term>
       <listitem>
        <para>
diff --git a/doc/src/sgml/ref/pg_dumpall.sgml b/doc/src/sgml/ref/pg_dumpall.sgml
index f337939..fcf5f77 100644
--- a/doc/src/sgml/ref/pg_dumpall.sgml
+++ b/doc/src/sgml/ref/pg_dumpall.sgml
@@ -301,6 +301,17 @@ PostgreSQL documentation
      </varlistentry>
 
      <varlistentry>
+      <term><option>--if-exists</option></term>
+      <listitem>
+       <para>
+        Use conditional commands (i.e. add an <literal>IF EXISTS</literal>
+        clause) to clean databases and other objects.  This option is not valid
+        unless <option>--clean</> is also specified.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><option>--inserts</option></term>
       <listitem>
        <para>
diff --git a/doc/src/sgml/ref/pg_restore.sgml b/doc/src/sgml/ref/pg_restore.sgml
index cd60b25..4bc30ce 100644
--- a/doc/src/sgml/ref/pg_restore.sgml
+++ b/doc/src/sgml/ref/pg_restore.sgml
@@ -109,7 +109,8 @@
       <listitem>
        <para>
         Clean (drop) database objects before recreating them.
-        (This might generate some harmless error messages, if any objects
+        (Unless <option>--if-exists</> is used,
+        this might generate some harmless error messages, if any objects
         were not present in the destination database.)
        </para>
       </listitem>
@@ -490,6 +491,17 @@
      </varlistentry>
 
      <varlistentry>
+      <term><option>--if-exists</option></term>
+      <listitem>
+       <para>
+        Use conditional commands (i.e. add an <literal>IF EXISTS</literal>
+        clause) when cleaning database objects.  This option is not valid
+        unless <option>--clean</> is also specified.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><option>--no-data-for-failed-tables</option></term>
       <listitem>
        <para>
diff --git a/src/bin/pg_dump/pg_backup.h b/src/bin/pg_dump/pg_backup.h
index 6927968..83f7216 100644
--- a/src/bin/pg_dump/pg_backup.h
+++ b/src/bin/pg_dump/pg_backup.h
@@ -113,6 +113,7 @@ typedef struct _restoreOptions
 	char	   *superuser;		/* Username to use as superuser */
 	char	   *use_role;		/* Issue SET ROLE to this */
 	int			dropSchema;
+	int			if_exists;
 	const char *filename;
 	int			dataOnly;
 	int			schemaOnly;
diff --git a/src/bin/pg_dump/pg_backup_archiver.c b/src/bin/pg_dump/pg_backup_archiver.c
index 2b36e45..8395373 100644
--- a/src/bin/pg_dump/pg_backup_archiver.c
+++ b/src/bin/pg_dump/pg_backup_archiver.c
@@ -413,8 +413,76 @@ RestoreArchive(Archive *AHX)
 				/* Select owner and schema as necessary */
 				_becomeOwner(AH, te);
 				_selectOutputSchema(AH, te->namespace);
-				/* Drop it */
-				ahprintf(AH, "%s", te->dropStmt);
+
+				/*
+				 * Now emit the DROP command, if the object has one.  Note we
+				 * don't necessarily emit it verbatim; at this point we add an
+				 * appropriate IF EXISTS clause, if the user requested it.
+				 */
+				if (*te->dropStmt != '\0')
+				{
+					if (!ropt->if_exists)
+					{
+						/* No --if-exists?  Then just use the original */
+						ahprintf(AH, "%s", te->dropStmt);
+					}
+					else
+					{
+						char		buffer[40];
+						char	   *mark;
+						char	   *dropStmt = pg_strdup(te->dropStmt);
+						PQExpBuffer	ftStmt = createPQExpBuffer();
+
+						/*
+						 * Need to inject IF EXISTS clause after ALTER TABLE
+						 * part in ALTER TABLE .. DROP statement
+						 */
+						if (strncmp(dropStmt, "ALTER TABLE", 11) == 0)
+						{
+							appendPQExpBuffer(ftStmt,
+											  "ALTER TABLE IF EXISTS");
+							dropStmt = dropStmt + 11;
+						}
+
+						/*
+						 * ALTER TABLE..ALTER COLUMN..DROP DEFAULT does not
+						 * support the IF EXISTS clause, and therefore we
+						 * simply emit the original command for such objects.
+						 * For other objects, we need to extract the first part
+						 * of the DROP which includes the object type.  Most of
+						 * the time this matches te->desc, so search for that;
+						 * however for the different kinds of CONSTRAINTs, we
+						 * know to search for hardcoded "DROP CONSTRAINT"
+						 * instead.
+						 */
+						if (strcmp(te->desc, "DEFAULT") == 0)
+							appendPQExpBuffer(ftStmt, "%s", dropStmt);
+						else
+						{
+							if (strcmp(te->desc, "CONSTRAINT") == 0 ||
+								strcmp(te->desc, "CHECK CONSTRAINT") == 0 ||
+								strcmp(te->desc, "FK CONSTRAINT") == 0)
+								strcpy(buffer, "DROP CONSTRAINT");
+							else
+								snprintf(buffer, sizeof(buffer), "DROP %s",
+										 te->desc);
+
+							mark = strstr(dropStmt, buffer);
+							Assert(mark != NULL);
+
+							*mark = '\0';
+							appendPQExpBuffer(ftStmt, "%s%s IF EXISTS%s",
+											  dropStmt, buffer,
+											  mark + strlen(buffer));
+						}
+
+						ahprintf(AH, "%s", ftStmt->data);
+
+						destroyPQExpBuffer(ftStmt);
+
+						pg_free(dropStmt);
+					}
+				}
 			}
 		}
 
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 4fabc1d..80431fb 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -132,6 +132,7 @@ static int	binary_upgrade = 0;
 static int	disable_dollar_quoting = 0;
 static int	dump_inserts = 0;
 static int	column_inserts = 0;
+static int	if_exists = 0;
 static int	no_security_labels = 0;
 static int	no_synchronized_snapshots = 0;
 static int	no_unlogged_table_data = 0;
@@ -345,6 +346,7 @@ main(int argc, char **argv)
 		{"disable-dollar-quoting", no_argument, &disable_dollar_quoting, 1},
 		{"disable-triggers", no_argument, &disable_triggers, 1},
 		{"exclude-table-data", required_argument, NULL, 4},
+		{"if-exists", no_argument, &if_exists, 1},
 		{"inserts", no_argument, &dump_inserts, 1},
 		{"lock-wait-timeout", required_argument, NULL, 2},
 		{"no-tablespaces", no_argument, &outputNoTablespaces, 1},
@@ -573,6 +575,9 @@ main(int argc, char **argv)
 		exit_nicely(1);
 	}
 
+	if (if_exists && !outputClean)
+		exit_horribly(NULL, "option --if-exists requires -c/--clean option\n");
+
 	/* Identify archive format to emit */
 	archiveFormat = parseArchiveFormat(format, &archiveMode);
 
@@ -805,6 +810,7 @@ main(int argc, char **argv)
 	ropt->dropSchema = outputClean;
 	ropt->dataOnly = dataOnly;
 	ropt->schemaOnly = schemaOnly;
+	ropt->if_exists = if_exists;
 	ropt->dumpSections = dumpSections;
 	ropt->aclsSkip = aclsSkip;
 	ropt->superuser = outputSuperuser;
@@ -886,6 +892,7 @@ help(const char *progname)
 	printf(_("  --disable-dollar-quoting     disable dollar quoting, use SQL standard quoting\n"));
 	printf(_("  --disable-triggers           disable triggers during data-only restore\n"));
 	printf(_("  --exclude-table-data=TABLE   do NOT dump data for the named table(s)\n"));
+	printf(_("  --if-exists                  use IF EXISTS when dropping objects\n"));
 	printf(_("  --inserts                    dump data as INSERT commands, rather than COPY\n"));
 	printf(_("  --no-security-labels         do not dump security label assignments\n"));
 	printf(_("  --no-synchronized-snapshots  do not use synchronized snapshots in parallel jobs\n"));
diff --git a/src/bin/pg_dump/pg_dumpall.c b/src/bin/pg_dump/pg_dumpall.c
index 193c1a0..7114f1d 100644
--- a/src/bin/pg_dump/pg_dumpall.c
+++ b/src/bin/pg_dump/pg_dumpall.c
@@ -73,6 +73,7 @@ static int	binary_upgrade = 0;
 static int	column_inserts = 0;
 static int	disable_dollar_quoting = 0;
 static int	disable_triggers = 0;
+static int	if_exists = 0;
 static int	inserts = 0;
 static int	no_tablespaces = 0;
 static int	use_setsessauth = 0;
@@ -119,6 +120,7 @@ main(int argc, char *argv[])
 		{"column-inserts", no_argument, &column_inserts, 1},
 		{"disable-dollar-quoting", no_argument, &disable_dollar_quoting, 1},
 		{"disable-triggers", no_argument, &disable_triggers, 1},
+		{"if-exists", no_argument, &if_exists, 1},
 		{"inserts", no_argument, &inserts, 1},
 		{"lock-wait-timeout", required_argument, NULL, 2},
 		{"no-tablespaces", no_argument, &no_tablespaces, 1},
@@ -334,6 +336,13 @@ main(int argc, char *argv[])
 		exit_nicely(1);
 	}
 
+	if (if_exists && !output_clean)
+	{
+		fprintf(stderr, _("%s: option --if-exists requires -c/--clean option\n"),
+				progname);
+		exit_nicely(1);
+	}
+
 	if (roles_only && tablespaces_only)
 	{
 		fprintf(stderr, _("%s: options -r/--roles-only and -t/--tablespaces-only cannot be used together\n"),
@@ -564,6 +573,7 @@ help(void)
 	printf(_("  --column-inserts             dump data as INSERT commands with column names\n"));
 	printf(_("  --disable-dollar-quoting     disable dollar quoting, use SQL standard quoting\n"));
 	printf(_("  --disable-triggers           disable triggers during data-only restore\n"));
+	printf(_("  --if-exists                  use IF EXISTS when dropping objects\n"));
 	printf(_("  --inserts                    dump data as INSERT commands, rather than COPY\n"));
 	printf(_("  --no-security-labels         do not dump security label assignments\n"));
 	printf(_("  --no-tablespaces             do not dump tablespace assignments\n"));
@@ -624,7 +634,9 @@ dropRoles(PGconn *conn)
 
 		rolename = PQgetvalue(res, i, i_rolname);
 
-		fprintf(OPF, "DROP ROLE %s;\n", fmtId(rolename));
+		fprintf(OPF, "DROP ROLE %s%s;\n",
+					 if_exists ? "IF EXISTS " : "",
+					 fmtId(rolename));
 	}
 
 	PQclear(res);
@@ -994,7 +1006,9 @@ dropTablespaces(PGconn *conn)
 	{
 		char	   *spcname = PQgetvalue(res, i, 0);
 
-		fprintf(OPF, "DROP TABLESPACE %s;\n", fmtId(spcname));
+		fprintf(OPF, "DROP TABLESPACE %s%s;\n",
+							 if_exists ? "IF EXISTS " : "",
+							 fmtId(spcname));
 	}
 
 	PQclear(res);
@@ -1148,7 +1162,9 @@ dropDBs(PGconn *conn)
 		if (strcmp(dbname, "template1") != 0 &&
 			strcmp(dbname, "postgres") != 0)
 		{
-			fprintf(OPF, "DROP DATABASE %s;\n", fmtId(dbname));
+			fprintf(OPF, "DROP DATABASE %s%s;\n",
+								 if_exists ? "IF EXISTS " : "",
+								 fmtId(dbname));
 		}
 	}
 
diff --git a/src/bin/pg_dump/pg_restore.c b/src/bin/pg_dump/pg_restore.c
index df9477b..f7f3f51 100644
--- a/src/bin/pg_dump/pg_restore.c
+++ b/src/bin/pg_dump/pg_restore.c
@@ -70,6 +70,7 @@ main(int argc, char **argv)
 	Archive    *AH;
 	char	   *inputFileSpec;
 	static int	disable_triggers = 0;
+	static int	if_exists = 0;
 	static int	no_data_for_failed_tables = 0;
 	static int	outputNoTablespaces = 0;
 	static int	use_setsessauth = 0;
@@ -110,6 +111,7 @@ main(int argc, char **argv)
 		 * the following options don't have an equivalent short option letter
 		 */
 		{"disable-triggers", no_argument, &disable_triggers, 1},
+		{"if-exists", no_argument, &if_exists, 1},
 		{"no-data-for-failed-tables", no_argument, &no_data_for_failed_tables, 1},
 		{"no-tablespaces", no_argument, &outputNoTablespaces, 1},
 		{"role", required_argument, NULL, 2},
@@ -336,6 +338,14 @@ main(int argc, char **argv)
 	opts->use_setsessauth = use_setsessauth;
 	opts->no_security_labels = no_security_labels;
 
+	if (if_exists && !opts->dropSchema)
+	{
+		fprintf(stderr, _("%s: option --if-exists requires -c/--clean option\n"),
+				progname);
+		exit_nicely(1);
+	}
+	opts->if_exists = if_exists;
+
 	if (opts->formatName)
 	{
 		switch (opts->formatName[0])
@@ -450,6 +460,7 @@ usage(const char *progname)
 	printf(_("  -x, --no-privileges          skip restoration of access privileges (grant/revoke)\n"));
 	printf(_("  -1, --single-transaction     restore as a single transaction\n"));
 	printf(_("  --disable-triggers           disable triggers during data-only restore\n"));
+	printf(_("  --if-exists                  use IF EXISTS when dropping objects\n"));
 	printf(_("  --no-data-for-failed-tables  do not restore data of tables that could not be\n"
 			 "                               created\n"));
 	printf(_("  --no-security-labels         do not restore security labels\n"));