More tests with USING INDEX replident and dropped indexes

diff --git a/src/include/commands/tablecmds.h b/src/include/commands/tablecmds.h
index c1581ad178..b163a82c52 100644
--- a/src/include/commands/tablecmds.h
+++ b/src/include/commands/tablecmds.h
@@ -61,6 +61,8 @@ extern void ExecuteTruncateGuts(List *explicit_rels, List *relids, List *relids_
 
 extern void SetRelationHasSubclass(Oid relationId, bool relhassubclass);
 
+extern void SetRelationReplIdent(Oid relationId, char ri_type);
+
 extern ObjectAddress renameatt(RenameStmt *stmt);
 
 extern ObjectAddress RenameConstraint(RenameStmt *stmt);
diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index 1be27eec52..d344a070ce 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -2195,6 +2195,18 @@ index_drop(Oid indexId, bool concurrent, bool concurrent_lock_mode)
 	if (userIndexRelation->rd_rel->relkind != RELKIND_PARTITIONED_INDEX)
 		RelationDropStorage(userIndexRelation);
 
+	/*
+	 * If the index to be dropped is marked as indisreplident, reset
+	 * pg_class.relreplident for the parent table.
+	 */
+	if (userIndexRelation->rd_index->indisreplident)
+	{
+		SetRelationReplIdent(heapId, REPLICA_IDENTITY_NOTHING);
+
+		/* make the update visible */
+		CommandCounterIncrement();
+	}
+
 	/*
 	 * Close and flush the index's relcache entry, to ensure relcache doesn't
 	 * try to rebuild it while we're deleting catalog entries. We keep the
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cd989c95e5..e11e8baf89 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -2976,6 +2976,41 @@ SetRelationHasSubclass(Oid relationId, bool relhassubclass)
 	table_close(relationRelation, RowExclusiveLock);
 }
 
+/*
+ * SetRelationReplIdent
+ *		Set the value of the relation's relreplident field in pg_class.
+ *
+ * NOTE: caller must be holding an appropriate lock on the relation.
+ * ShareUpdateExclusiveLock is sufficient.
+ */
+void
+SetRelationReplIdent(Oid relationId, char ri_type)
+{
+	Relation	relationRelation;
+	HeapTuple	tuple;
+	Form_pg_class classtuple;
+
+	/*
+	 * Fetch a modifiable copy of the tuple, modify it, update pg_class.
+	 */
+	relationRelation = table_open(RelationRelationId, RowExclusiveLock);
+	tuple = SearchSysCacheCopy1(RELOID,
+								ObjectIdGetDatum(relationId));
+	if (!HeapTupleIsValid(tuple))
+		elog(ERROR, "cache lookup failed for relation \"%s\"",
+			 get_rel_name(relationId));
+	classtuple = (Form_pg_class) GETSTRUCT(tuple);
+
+	if (classtuple->relreplident != ri_type)
+	{
+		classtuple->relreplident = ri_type;
+		CatalogTupleUpdate(relationRelation, &tuple->t_self, tuple);
+	}
+
+	heap_freetuple(tuple);
+	table_close(relationRelation, RowExclusiveLock);
+}
+
 /*
  *		renameatt_check			- basic sanity checks before attribute rename
  */
@@ -14384,31 +14419,12 @@ relation_mark_replica_identity(Relation rel, char ri_type, Oid indexOid,
 							   bool is_internal)
 {
 	Relation	pg_index;
-	Relation	pg_class;
-	HeapTuple	pg_class_tuple;
 	HeapTuple	pg_index_tuple;
-	Form_pg_class pg_class_form;
 	Form_pg_index pg_index_form;
-
 	ListCell   *index;
 
-	/*
-	 * Check whether relreplident has changed, and update it if so.
-	 */
-	pg_class = table_open(RelationRelationId, RowExclusiveLock);
-	pg_class_tuple = SearchSysCacheCopy1(RELOID,
-										 ObjectIdGetDatum(RelationGetRelid(rel)));
-	if (!HeapTupleIsValid(pg_class_tuple))
-		elog(ERROR, "cache lookup failed for relation \"%s\"",
-			 RelationGetRelationName(rel));
-	pg_class_form = (Form_pg_class) GETSTRUCT(pg_class_tuple);
-	if (pg_class_form->relreplident != ri_type)
-	{
-		pg_class_form->relreplident = ri_type;
-		CatalogTupleUpdate(pg_class, &pg_class_tuple->t_self, pg_class_tuple);
-	}
-	table_close(pg_class, RowExclusiveLock);
-	heap_freetuple(pg_class_tuple);
+	/* update relreplident if necessary */
+	SetRelationReplIdent(RelationGetRelid(rel), ri_type);
 
 	/*
 	 * Check whether the correct index is marked indisreplident; if so, we're
diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index fc329c5cff..6e293c9cca 100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -2144,8 +2144,7 @@ SCRAM-SHA-256$<replaceable>&lt;iteration count&gt;</replaceable>:<replaceable>&l
        <literal>n</literal> = nothing,
        <literal>f</literal> = all columns,
        <literal>i</literal> = index with
-       <structfield>indisreplident</structfield> set (same as nothing if the
-       index used has been dropped)
+       <structfield>indisreplident</structfield> set
       </para></entry>
      </row>
 
diff --git a/contrib/test_decoding/expected/ddl.out b/contrib/test_decoding/expected/ddl.out
index d79cd316b7..3e7228a937 100644
--- a/contrib/test_decoding/expected/ddl.out
+++ b/contrib/test_decoding/expected/ddl.out
@@ -565,6 +565,50 @@ UPDATE table_with_unique_not_null SET data = 3 WHERE data = 2;
 UPDATE table_with_unique_not_null SET id = -id;
 UPDATE table_with_unique_not_null SET id = -id;
 DELETE FROM table_with_unique_not_null WHERE data = 3;
+-- check tables with dropped indexes used in REPLICA IDENTITY
+-- with primary key
+CREATE TABLE table_dropped_index_with_pk (a int PRIMARY KEY, b int, c int);
+CREATE UNIQUE INDEX table_dropped_index_with_pk_idx
+  ON table_dropped_index_with_pk(a);
+ALTER TABLE table_dropped_index_with_pk REPLICA IDENTITY
+  USING INDEX table_dropped_index_with_pk_idx;
+DROP INDEX table_dropped_index_with_pk_idx;
+SELECT relreplident FROM pg_class
+  WHERE oid = 'table_dropped_index_with_pk'::regclass;
+ relreplident 
+--------------
+ n
+(1 row)
+
+INSERT INTO table_dropped_index_with_pk VALUES (1,1,1), (2,2,2), (3,3,3);
+UPDATE table_dropped_index_with_pk SET a = 4 WHERE a = 1;
+UPDATE table_dropped_index_with_pk SET b = 5 WHERE a = 2;
+UPDATE table_dropped_index_with_pk SET b = 6, c = 7 WHERE a = 3;
+DELETE FROM table_dropped_index_with_pk WHERE b = 1;
+DELETE FROM table_dropped_index_with_pk WHERE a = 3;
+DROP TABLE table_dropped_index_with_pk;
+-- without primary key
+CREATE TABLE table_dropped_index_no_pk (a int NOT NULL, b int, c int);
+CREATE UNIQUE INDEX table_dropped_index_no_pk_idx
+  ON table_dropped_index_no_pk(a);
+ALTER TABLE table_dropped_index_no_pk REPLICA IDENTITY
+  USING INDEX table_dropped_index_no_pk_idx;
+INSERT INTO table_dropped_index_no_pk VALUES (1,1,1), (2,2,2), (3,3,3);
+DROP INDEX table_dropped_index_no_pk_idx;
+SELECT relreplident FROM pg_class
+  WHERE oid = 'table_dropped_index_no_pk'::regclass;
+ relreplident 
+--------------
+ n
+(1 row)
+
+INSERT INTO table_dropped_index_no_pk VALUES (1,1,1), (2,2,2), (3,3,3);
+UPDATE table_dropped_index_no_pk SET a = 4 WHERE a = 1;
+UPDATE table_dropped_index_no_pk SET b = 5 WHERE a = 2;
+UPDATE table_dropped_index_no_pk SET b = 6, c = 7 WHERE a = 3;
+DELETE FROM table_dropped_index_no_pk WHERE b = 1;
+DELETE FROM table_dropped_index_no_pk WHERE a = 3;
+DROP TABLE table_dropped_index_no_pk;
 -- check toast support
 BEGIN;
 CREATE SEQUENCE toasttable_rand_seq START 79 INCREMENT 1499; -- portable "random"
@@ -682,6 +726,56 @@ SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'inc
  table public.table_with_unique_not_null: DELETE: id[integer]:4
  COMMIT
  BEGIN
+ table public.table_dropped_index_with_pk: INSERT: a[integer]:1 b[integer]:1 c[integer]:1
+ table public.table_dropped_index_with_pk: INSERT: a[integer]:2 b[integer]:2 c[integer]:2
+ table public.table_dropped_index_with_pk: INSERT: a[integer]:3 b[integer]:3 c[integer]:3
+ COMMIT
+ BEGIN
+ table public.table_dropped_index_with_pk: UPDATE: a[integer]:4 b[integer]:1 c[integer]:1
+ COMMIT
+ BEGIN
+ table public.table_dropped_index_with_pk: UPDATE: a[integer]:2 b[integer]:5 c[integer]:2
+ COMMIT
+ BEGIN
+ table public.table_dropped_index_with_pk: UPDATE: a[integer]:3 b[integer]:6 c[integer]:7
+ COMMIT
+ BEGIN
+ table public.table_dropped_index_with_pk: DELETE: (no-tuple-data)
+ COMMIT
+ BEGIN
+ table public.table_dropped_index_with_pk: DELETE: (no-tuple-data)
+ COMMIT
+ BEGIN
+ table public.table_dropped_index_no_pk: INSERT: a[integer]:1 b[integer]:1 c[integer]:1
+ table public.table_dropped_index_no_pk: INSERT: a[integer]:2 b[integer]:2 c[integer]:2
+ table public.table_dropped_index_no_pk: INSERT: a[integer]:3 b[integer]:3 c[integer]:3
+ COMMIT
+ BEGIN
+ table public.table_dropped_index_no_pk: INSERT: a[integer]:1 b[integer]:1 c[integer]:1
+ table public.table_dropped_index_no_pk: INSERT: a[integer]:2 b[integer]:2 c[integer]:2
+ table public.table_dropped_index_no_pk: INSERT: a[integer]:3 b[integer]:3 c[integer]:3
+ COMMIT
+ BEGIN
+ table public.table_dropped_index_no_pk: UPDATE: a[integer]:4 b[integer]:1 c[integer]:1
+ table public.table_dropped_index_no_pk: UPDATE: a[integer]:4 b[integer]:1 c[integer]:1
+ COMMIT
+ BEGIN
+ table public.table_dropped_index_no_pk: UPDATE: a[integer]:2 b[integer]:5 c[integer]:2
+ table public.table_dropped_index_no_pk: UPDATE: a[integer]:2 b[integer]:5 c[integer]:2
+ COMMIT
+ BEGIN
+ table public.table_dropped_index_no_pk: UPDATE: a[integer]:3 b[integer]:6 c[integer]:7
+ table public.table_dropped_index_no_pk: UPDATE: a[integer]:3 b[integer]:6 c[integer]:7
+ COMMIT
+ BEGIN
+ table public.table_dropped_index_no_pk: DELETE: (no-tuple-data)
+ table public.table_dropped_index_no_pk: DELETE: (no-tuple-data)
+ COMMIT
+ BEGIN
+ table public.table_dropped_index_no_pk: DELETE: (no-tuple-data)
+ table public.table_dropped_index_no_pk: DELETE: (no-tuple-data)
+ COMMIT
+ BEGIN
  table public.toasttable: INSERT: id[integer]:1 toasted_col1[text]:'123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423424425426427428429430431432433434435436437438439440441442443444445446447448449450451452453454455456457458459460461462463464465466467468469470471472473474475476477478479480481482483484485486487488489490491492493494495496497498499500501502503504505506507508509510511512513514515516517518519520521522523524525526527528529530531532533534535536537538539540541542543544545546547548549550551552553554555556557558559560561562563564565566567568569570571572573574575576577578579580581582583584585586587588589590591592593594595596597598599600601602603604605606607608609610611612613614615616617618619620621622623624625626627628629630631632633634635636637638639640641642643644645646647648649650651652653654655656657658659660661662663664665666667668669670671672673674675676677678679680681682683684685686687688689690691692693694695696697698699700701702703704705706707708709710711712713714715716717718719720721722723724725726727728729730731732733734735736737738739740741742743744745746747748749750751752753754755756757758759760761762763764765766767768769770771772773774775776777778779780781782783784785786787788789790791792793794795796797798799800801802803804805806807808809810811812813814815816817818819820821822823824825826827828829830831832833834835836837838839840841842843844845846847848849850851852853854855856857858859860861862863864865866867868869870871872873874875876877878879880881882883884885886887888889890891892893894895896897898899900901902903904905906907908909910911912913914915916917918919920921922923924925926927928929930931932933934935936937938939940941942943944945946947948949950951952953954955956957958959960961962963964965966967968969970971972973974975976977978979980981982983984985986987988989990991992993994995996997998999100010011002100310041005100610071008100910101011101210131014101510161017101810191020102110221023102410251026102710281029103010311032103310341035103610371038103910401041104210431044104510461047104810491050105110521053105410551056105710581059106010611062106310641065106610671068106910701071107210731074107510761077107810791080108110821083108410851086108710881089109010911092109310941095109610971098109911001101110211031104110511061107110811091110111111121113111411151116111711181119112011211122112311241125112611271128112911301131113211331134113511361137113811391140114111421143114411451146114711481149115011511152115311541155115611571158115911601161116211631164116511661167116811691170117111721173117411751176117711781179118011811182118311841185118611871188118911901191119211931194119511961197119811991200120112021203120412051206120712081209121012111212121312141215121612171218121912201221122212231224122512261227122812291230123112321233123412351236123712381239124012411242124312441245124612471248124912501251125212531254125512561257125812591260126112621263126412651266126712681269127012711272127312741275127612771278127912801281128212831284128512861287128812891290129112921293129412951296129712981299130013011302130313041305130613071308130913101311131213131314131513161317131813191320132113221323132413251326132713281329133013311332133313341335133613371338133913401341134213431344134513461347134813491350135113521353135413551356135713581359136013611362136313641365136613671368136913701371137213731374137513761377137813791380138113821383138413851386138713881389139013911392139313941395139613971398139914001401140214031404140514061407140814091410141114121413141414151416141714181419142014211422142314241425142614271428142914301431143214331434143514361437143814391440144114421443144414451446144714481449145014511452145314541455145614571458145914601461146214631464146514661467146814691470147114721473147414751476147714781479148014811482148314841485148614871488148914901491149214931494149514961497149814991500150115021503150415051506150715081509151015111512151315141515151615171518151915201521152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rand1[double precision]:79 toasted_col2[text]:null rand2[double precision]:1578
  COMMIT
  BEGIN
@@ -690,7 +784,7 @@ SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'inc
  BEGIN
  table public.toasttable: UPDATE: id[integer]:1 toasted_col1[text]:'12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667686970717273747576777879808182838485868788899091929394959697989910010110210310410510610710810911011111211311411511611711811912012112212312412512612712812913013113213313413513613713813914014114214314414514614714814915015115215315415515615715815916016116216316416516616716816917017117217317417517617717817918018118218318418518618718818919019119219319419519619719819920020120220320420520620720820921021121221321421521621721821922022122222322422522622722822923023123223323423523623723823924024124224324424524624724824925025125225325425525625725825926026126226326426526626726826927027127227327427527627727827928028128228328428528628728828929029129229329429529629729829930030130230330430530630730830931031131231331431531631731831932032132232332432532632732832933033133233333433533633733833934034134234334434534634734834935035135235335435535635735835936036136236336436536636736836937037137237337437537637737837938038138238338438538638738838939039139239339439539639739839940040140240340440540640740840941041141241341441541641741841942042142242342442542642742842943043143243343443543643743843944044144244344444544644744844945045145245345445545645745845946046146246346446546646746846947047147247347447547647747847948048148248348448548648748848949049149249349449549649749849950050150250350450550650750850951051151251351451551651751851952052152252352452552652752852953053153253353453553653753853954054154254354454554654754854955055155255355455555655755855956056156256356456556656756856957057157257357457557657757857958058158258358458558658758858959059159259359459559659759859960060160260360460560660760860961061161261361461561661761861962062162262362462562662762862963063163263363463563663763863964064164264364464564664764864965065165265365465565665765865966066166266366466566666766866967067167267367467567667767867968068168268368468568668768868969069169269369469569669769869970070170270370470570670770870971071171271371471571671771871972072172272372472572672772872973073173273373473573673773873974074174274374474574674774874975075175275375475575675775875976076176276376476576676776876977077177277377477577677777877978078178278378478578678778878979079179279379479579679779879980080180280380480580680780880981081181281381481581681781881982082182282382482582682782882983083183283383483583683783883984084184284384484584684784884985085185285385485585685785885986086186286386486586686786886987087187287387487587687787887988088188288388488588688788888989089189289389489589689789889990090190290390490590690790890991091191291391491591691791891992092192292392492592692792892993093193293393493593693793893994094194294394494594694794894995095195295395495595695795895996096196296396496596696796896997097197297397497597697797897998098198298398498598698798898999099199299399499599699799899910001001100210031004100510061007100810091010101110121013101410151016101710181019102010211022102310241025102610271028102910301031103210331034103510361037103810391040104110421043104410451046104710481049105010511052105310541055105610571058105910601061106210631064106510661067106810691070107110721073107410751076107710781079108010811082108310841085108610871088108910901091109210931094109510961097109810991100110111021103110411051106110711081109111011111112111311141115111611171118111911201121112211231124112511261127112811291130113111321133113411351136113711381139114011411142114311441145114611471148114911501151115211531154115511561157115811591160116111621163116411651166116711681169117011711172117311741175117611771178117911801181118211831184118511861187118811891190119111921193119411951196119711981199120012011202120312041205120612071208120912101211121212131214121512161217121812191220122112221223122412251226122712281229123012311232123312341235123612371238123912401241124212431244124512461247124812491250125112521253125412551256125712581259126012611262126312641265126612671268126912701271127212731274127512761277127812791280128112821283128412851286128712881289129012911292129312941295129612971298129913001301130213031304130513061307130813091310131113121313131413151316131713181319132013211322132313241325132613271328132913301331133213331334133513361337133813391340134113421343134413451346134713481349135013511352135313541355135613571358135913601361136213631364136513661367136813691370137113721373137413751376137713781379138013811382138313841385138613871388138913901391139213931394139513961397139813991400140114021403140414051406140714081409141014111412141314141415141614171418141914201421142214231424142514261427142814291430143114321433143414351436143714381439144014411442144314441445144614471448144914501451145214531454145514561457145814591460146114621463146414651466146714681469147014711472147314741475147614771478147914801481148214831484148514861487148814891490149114921493149414951496149714981499150015011502150315041505150615071508150915101511151215131514151515161517151815191520152115221523152415251526152715281529153015311532153315341535153615371538153915401541154215431544154515461547154815491550155115521553155415551556155715581559156015611562156315641565156615671568156915701571157215731574157515761577157815791580158115821583158415851586158715881589159015911592159315941595159615971598159916001601160216031604160516061607160816091610161116121613161416151616161716181619162016211622162316241625162616271628162916301631163216331634163516361637163816391640164116421643164416451646164716481649165016511652165316541655165616571658165916601661166216631664166516661667166816691670167116721673167416751676167716781679168016811682168316841685168616871688168916901691169216931694169516961697169816991700170117021703170417051706170717081709171017111712171317141715171617171718171917201721172217231724172517261727172817291730173117321733173417351736173717381739174017411742174317441745174617471748174917501751175217531754175517561757175817591760176117621763176417651766176717681769177017711772177317741775177617771778177917801781178217831784178517861787178817891790179117921793179417951796179717981799180018011802180318041805180618071808180918101811181218131814181518161817181818191820182118221823182418251826182718281829183018311832183318341835183618371838183918401841184218431844184518461847184818491850185118521853185418551856185718581859186018611862186318641865186618671868186918701871187218731874187518761877187818791880188118821883188418851886188718881889189018911892189318941895189618971898189919001901190219031904190519061907190819091910191119121913191419151916191719181919192019211922192319241925192619271928192919301931193219331934193519361937193819391940194119421943194419451946194719481949195019511952195319541955195619571958195919601961196219631964196519661967196819691970197119721973197419751976197719781979198019811982198319841985198619871988198919901991199219931994199519961997199819992000' rand1[double precision]:79 toasted_col2[text]:null rand2[double precision]:1578
  COMMIT
-(103 rows)
+(153 rows)
 
 INSERT INTO toasttable(toasted_col1) SELECT string_agg(g.i::text, '') FROM generate_series(1, 2000) g(i);
 -- update of second column, first column unchanged
diff --git a/contrib/test_decoding/sql/ddl.sql b/contrib/test_decoding/sql/ddl.sql
index 2c4823e578..cbb6966e34 100644
--- a/contrib/test_decoding/sql/ddl.sql
+++ b/contrib/test_decoding/sql/ddl.sql
@@ -345,6 +345,42 @@ UPDATE table_with_unique_not_null SET id = -id;
 UPDATE table_with_unique_not_null SET id = -id;
 DELETE FROM table_with_unique_not_null WHERE data = 3;
 
+-- check tables with dropped indexes used in REPLICA IDENTITY
+-- with primary key
+CREATE TABLE table_dropped_index_with_pk (a int PRIMARY KEY, b int, c int);
+CREATE UNIQUE INDEX table_dropped_index_with_pk_idx
+  ON table_dropped_index_with_pk(a);
+ALTER TABLE table_dropped_index_with_pk REPLICA IDENTITY
+  USING INDEX table_dropped_index_with_pk_idx;
+DROP INDEX table_dropped_index_with_pk_idx;
+SELECT relreplident FROM pg_class
+  WHERE oid = 'table_dropped_index_with_pk'::regclass;
+INSERT INTO table_dropped_index_with_pk VALUES (1,1,1), (2,2,2), (3,3,3);
+UPDATE table_dropped_index_with_pk SET a = 4 WHERE a = 1;
+UPDATE table_dropped_index_with_pk SET b = 5 WHERE a = 2;
+UPDATE table_dropped_index_with_pk SET b = 6, c = 7 WHERE a = 3;
+DELETE FROM table_dropped_index_with_pk WHERE b = 1;
+DELETE FROM table_dropped_index_with_pk WHERE a = 3;
+DROP TABLE table_dropped_index_with_pk;
+
+-- without primary key
+CREATE TABLE table_dropped_index_no_pk (a int NOT NULL, b int, c int);
+CREATE UNIQUE INDEX table_dropped_index_no_pk_idx
+  ON table_dropped_index_no_pk(a);
+ALTER TABLE table_dropped_index_no_pk REPLICA IDENTITY
+  USING INDEX table_dropped_index_no_pk_idx;
+INSERT INTO table_dropped_index_no_pk VALUES (1,1,1), (2,2,2), (3,3,3);
+DROP INDEX table_dropped_index_no_pk_idx;
+SELECT relreplident FROM pg_class
+  WHERE oid = 'table_dropped_index_no_pk'::regclass;
+INSERT INTO table_dropped_index_no_pk VALUES (1,1,1), (2,2,2), (3,3,3);
+UPDATE table_dropped_index_no_pk SET a = 4 WHERE a = 1;
+UPDATE table_dropped_index_no_pk SET b = 5 WHERE a = 2;
+UPDATE table_dropped_index_no_pk SET b = 6, c = 7 WHERE a = 3;
+DELETE FROM table_dropped_index_no_pk WHERE b = 1;
+DELETE FROM table_dropped_index_no_pk WHERE a = 3;
+DROP TABLE table_dropped_index_no_pk;
+
 -- check toast support
 BEGIN;
 CREATE SEQUENCE toasttable_rand_seq START 79 INCREMENT 1499; -- portable "random"

From 277d9b53e2be9098e72167b5de2a52c40e6e8542 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Wed, 26 Aug 2020 20:59:34 +0900
Subject: [PATCH v3] Reset pg_class.relreplident when associated replica index
 is dropped

When an index associated to REPLICA IDENTITY USING INDEX gets dropped,
relreplident gets set to 'i', which can be confusing as the catalogs
have a state inconsistent with pg_index that lacks an associated entry
marked with indisreplident.  This changes the logic so as such an index
dropped leads to 'n' to be set for the parent table, equivalent to
REPLICA IDENTITY NOTHING.

Author: Michael Paquier
Reviewed-by: Masahiko Sawada, Rahila Syed, Euler Taveira
Discussion: https://postgr.es/m/20200522035028.GO2355@paquier.xyz
---
 src/include/commands/tablecmds.h              |  2 +
 src/backend/catalog/index.c                   | 12 ++++
 src/backend/commands/tablecmds.c              | 58 ++++++++++++-------
 .../regress/expected/replica_identity.out     | 30 ++++++++++
 src/test/regress/sql/replica_identity.sql     | 22 +++++++
 doc/src/sgml/catalogs.sgml                    |  3 +-
 6 files changed, 104 insertions(+), 23 deletions(-)

diff --git a/src/include/commands/tablecmds.h b/src/include/commands/tablecmds.h
index c1581ad178..b163a82c52 100644
--- a/src/include/commands/tablecmds.h
+++ b/src/include/commands/tablecmds.h
@@ -61,6 +61,8 @@ extern void ExecuteTruncateGuts(List *explicit_rels, List *relids, List *relids_
 
 extern void SetRelationHasSubclass(Oid relationId, bool relhassubclass);
 
+extern void SetRelationReplIdent(Oid relationId, char ri_type);
+
 extern ObjectAddress renameatt(RenameStmt *stmt);
 
 extern ObjectAddress RenameConstraint(RenameStmt *stmt);
diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index 1be27eec52..d344a070ce 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -2195,6 +2195,18 @@ index_drop(Oid indexId, bool concurrent, bool concurrent_lock_mode)
 	if (userIndexRelation->rd_rel->relkind != RELKIND_PARTITIONED_INDEX)
 		RelationDropStorage(userIndexRelation);
 
+	/*
+	 * If the index to be dropped is marked as indisreplident, reset
+	 * pg_class.relreplident for the parent table.
+	 */
+	if (userIndexRelation->rd_index->indisreplident)
+	{
+		SetRelationReplIdent(heapId, REPLICA_IDENTITY_NOTHING);
+
+		/* make the update visible */
+		CommandCounterIncrement();
+	}
+
 	/*
 	 * Close and flush the index's relcache entry, to ensure relcache doesn't
 	 * try to rebuild it while we're deleting catalog entries. We keep the
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index d2b15a3387..968cb41f98 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -3020,6 +3020,41 @@ SetRelationHasSubclass(Oid relationId, bool relhassubclass)
 	table_close(relationRelation, RowExclusiveLock);
 }
 
+/*
+ * SetRelationReplIdent
+ *		Set the value of the relation's relreplident field in pg_class.
+ *
+ * NOTE: caller must be holding an appropriate lock on the relation.
+ * ShareUpdateExclusiveLock is sufficient.
+ */
+void
+SetRelationReplIdent(Oid relationId, char ri_type)
+{
+	Relation	relationRelation;
+	HeapTuple	tuple;
+	Form_pg_class classtuple;
+
+	/*
+	 * Fetch a modifiable copy of the tuple, modify it, update pg_class.
+	 */
+	relationRelation = table_open(RelationRelationId, RowExclusiveLock);
+	tuple = SearchSysCacheCopy1(RELOID,
+								ObjectIdGetDatum(relationId));
+	if (!HeapTupleIsValid(tuple))
+		elog(ERROR, "cache lookup failed for relation \"%s\"",
+			 get_rel_name(relationId));
+	classtuple = (Form_pg_class) GETSTRUCT(tuple);
+
+	if (classtuple->relreplident != ri_type)
+	{
+		classtuple->relreplident = ri_type;
+		CatalogTupleUpdate(relationRelation, &tuple->t_self, tuple);
+	}
+
+	heap_freetuple(tuple);
+	table_close(relationRelation, RowExclusiveLock);
+}
+
 /*
  *		renameatt_check			- basic sanity checks before attribute rename
  */
@@ -14487,31 +14522,12 @@ relation_mark_replica_identity(Relation rel, char ri_type, Oid indexOid,
 							   bool is_internal)
 {
 	Relation	pg_index;
-	Relation	pg_class;
-	HeapTuple	pg_class_tuple;
 	HeapTuple	pg_index_tuple;
-	Form_pg_class pg_class_form;
 	Form_pg_index pg_index_form;
-
 	ListCell   *index;
 
-	/*
-	 * Check whether relreplident has changed, and update it if so.
-	 */
-	pg_class = table_open(RelationRelationId, RowExclusiveLock);
-	pg_class_tuple = SearchSysCacheCopy1(RELOID,
-										 ObjectIdGetDatum(RelationGetRelid(rel)));
-	if (!HeapTupleIsValid(pg_class_tuple))
-		elog(ERROR, "cache lookup failed for relation \"%s\"",
-			 RelationGetRelationName(rel));
-	pg_class_form = (Form_pg_class) GETSTRUCT(pg_class_tuple);
-	if (pg_class_form->relreplident != ri_type)
-	{
-		pg_class_form->relreplident = ri_type;
-		CatalogTupleUpdate(pg_class, &pg_class_tuple->t_self, pg_class_tuple);
-	}
-	table_close(pg_class, RowExclusiveLock);
-	heap_freetuple(pg_class_tuple);
+	/* update relreplident if necessary */
+	SetRelationReplIdent(RelationGetRelid(rel), ri_type);
 
 	/*
 	 * Check whether the correct index is marked indisreplident; if so, we're
diff --git a/src/test/regress/expected/replica_identity.out b/src/test/regress/expected/replica_identity.out
index 79002197a7..340f8615f5 100644
--- a/src/test/regress/expected/replica_identity.out
+++ b/src/test/regress/expected/replica_identity.out
@@ -227,3 +227,33 @@ DROP TABLE test_replica_identity;
 DROP TABLE test_replica_identity2;
 DROP TABLE test_replica_identity3;
 DROP TABLE test_replica_identity_othertable;
+--
+-- Test that DROP INDEX on a index used for REPLICA IDENTITY sets
+-- relreplident back to NOTHING.
+--
+CREATE TABLE test_replica_identity_4 (id int NOT NULL);
+CREATE UNIQUE INDEX test_replica_index_4 ON test_replica_identity_4(id);
+ALTER TABLE test_replica_identity_4 REPLICA IDENTITY
+  USING INDEX test_replica_index_4;
+DROP INDEX test_replica_index_4;
+SELECT relreplident FROM pg_class WHERE oid = 'test_replica_identity_4'::regclass;
+ relreplident 
+--------------
+ n
+(1 row)
+
+DROP TABLE test_replica_identity_4;
+-- Partitioned table
+CREATE TABLE test_replica_part (id int NOT NULL)
+  PARTITION BY RANGE (id);
+CREATE UNIQUE INDEX test_replica_part_index ON test_replica_part(id);
+ALTER TABLE test_replica_part REPLICA IDENTITY
+  USING INDEX test_replica_part_index;
+DROP INDEX test_replica_part_index;
+SELECT relreplident FROM pg_class WHERE oid = 'test_replica_part'::regclass;
+ relreplident 
+--------------
+ n
+(1 row)
+
+DROP TABLE test_replica_part;
diff --git a/src/test/regress/sql/replica_identity.sql b/src/test/regress/sql/replica_identity.sql
index a5ac8f5567..18220a595b 100644
--- a/src/test/regress/sql/replica_identity.sql
+++ b/src/test/regress/sql/replica_identity.sql
@@ -98,3 +98,25 @@ DROP TABLE test_replica_identity;
 DROP TABLE test_replica_identity2;
 DROP TABLE test_replica_identity3;
 DROP TABLE test_replica_identity_othertable;
+
+--
+-- Test that DROP INDEX on a index used for REPLICA IDENTITY sets
+-- relreplident back to NOTHING.
+--
+
+CREATE TABLE test_replica_identity_4 (id int NOT NULL);
+CREATE UNIQUE INDEX test_replica_index_4 ON test_replica_identity_4(id);
+ALTER TABLE test_replica_identity_4 REPLICA IDENTITY
+  USING INDEX test_replica_index_4;
+DROP INDEX test_replica_index_4;
+SELECT relreplident FROM pg_class WHERE oid = 'test_replica_identity_4'::regclass;
+DROP TABLE test_replica_identity_4;
+-- Partitioned table
+CREATE TABLE test_replica_part (id int NOT NULL)
+  PARTITION BY RANGE (id);
+CREATE UNIQUE INDEX test_replica_part_index ON test_replica_part(id);
+ALTER TABLE test_replica_part REPLICA IDENTITY
+  USING INDEX test_replica_part_index;
+DROP INDEX test_replica_part_index;
+SELECT relreplident FROM pg_class WHERE oid = 'test_replica_part'::regclass;
+DROP TABLE test_replica_part;
diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index 9fe260ecff..601b3d448c 100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -2144,8 +2144,7 @@ SCRAM-SHA-256$<replaceable>&lt;iteration count&gt;</replaceable>:<replaceable>&l
        <literal>n</literal> = nothing,
        <literal>f</literal> = all columns,
        <literal>i</literal> = index with
-       <structfield>indisreplident</structfield> set (same as nothing if the
-       index used has been dropped)
+       <structfield>indisreplident</structfield> set
       </para></entry>
      </row>
 
-- 
2.28.0

From 8893acae8b4d14b1cccb3bdcf8c23e46215d2060 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Thu, 27 Aug 2020 11:27:04 +0900
Subject: [PATCH v4] Reset pg_class.relreplident when associated replica index
 is dropped

When an index associated to REPLICA IDENTITY USING INDEX gets dropped,
relreplident gets set to 'i', which can be confusing as the catalogs
have a state inconsistent with pg_index that lacks an associated entry
marked with indisreplident.  This changes the logic so as such an index
dropped leads to 'n' to be set for the parent table, equivalent to
REPLICA IDENTITY NOTHING.

Author: Michael Paquier
Reviewed-by: Masahiko Sawada, Rahila Syed, Euler Taveira
Discussion: https://postgr.es/m/20200522035028.GO2355@paquier.xyz
---
 src/include/commands/tablecmds.h              |  2 +
 src/backend/catalog/index.c                   | 43 +++++++++++++-
 src/backend/commands/tablecmds.c              | 58 ++++++++++++-------
 .../regress/expected/replica_identity.out     | 30 ++++++++++
 src/test/regress/sql/replica_identity.sql     | 22 +++++++
 doc/src/sgml/catalogs.sgml                    |  3 +-
 6 files changed, 132 insertions(+), 26 deletions(-)

diff --git a/src/include/commands/tablecmds.h b/src/include/commands/tablecmds.h
index c1581ad178..b163a82c52 100644
--- a/src/include/commands/tablecmds.h
+++ b/src/include/commands/tablecmds.h
@@ -61,6 +61,8 @@ extern void ExecuteTruncateGuts(List *explicit_rels, List *relids, List *relids_
 
 extern void SetRelationHasSubclass(Oid relationId, bool relhassubclass);
 
+extern void SetRelationReplIdent(Oid relationId, char ri_type);
+
 extern ObjectAddress renameatt(RenameStmt *stmt);
 
 extern ObjectAddress RenameConstraint(RenameStmt *stmt);
diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index 1be27eec52..ccdda7561a 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -2005,6 +2005,7 @@ index_drop(Oid indexId, bool concurrent, bool concurrent_lock_mode)
 	Relation	indexRelation;
 	HeapTuple	tuple;
 	bool		hasexprs;
+	bool		resetreplident;
 	LockRelId	heaprelid,
 				indexrelid;
 	LOCKTAG		heaplocktag;
@@ -2048,6 +2049,15 @@ index_drop(Oid indexId, bool concurrent, bool concurrent_lock_mode)
 	 */
 	CheckTableNotInUse(userIndexRelation, "DROP INDEX");
 
+	/*
+	 * Check if the REPLICA IDENTITY of the parent relation needs to be
+	 * reset.  This should be done only if the index to drop here is
+	 * marked as used in a replica identity.  We cannot rely on the
+	 * contents of pg_index for the index either as a concurrent drop
+	 * may have changed indisreplident already.
+	 */
+	resetreplident = userIndexRelation->rd_index->indisreplident;
+
 	/*
 	 * Drop Index Concurrently is more or less the reverse process of Create
 	 * Index Concurrently.
@@ -2159,10 +2169,32 @@ index_drop(Oid indexId, bool concurrent, bool concurrent_lock_mode)
 
 		/* Finish invalidation of index and mark it as dead */
 		index_concurrently_set_dead(heapId, indexId);
+	}
 
+	/*
+	 * If the index to be dropped was marked as indisreplident (it could
+	 * have been updated when clearing indisvalid previously), reset
+	 * pg_class.relreplident for the parent table.  Note that this part
+	 * needs to be done in the same transaction as the one marking the
+	 * index as invalid, so as we never finish with the case where the
+	 * parent's replica identity is based on an index, without any index
+	 * marked with indisreplident.
+	 */
+	if (resetreplident)
+	{
+		SetRelationReplIdent(heapId, REPLICA_IDENTITY_NOTHING);
+
+		/* make the update visible, mandatory for the non-concurrent case */
+		CommandCounterIncrement();
+	}
+
+	/* continue the concurrent process */
+	if (concurrent)
+	{
 		/*
-		 * Again, commit the transaction to make the pg_index update visible
-		 * to other sessions.
+		 * Again, commit the transaction to make the pg_index and pg_class
+		 * (in the case where indisreplident is set) updates are visible to
+		 * other sessions.
 		 */
 		CommitTransactionCommand();
 		StartTransactionCommand();
@@ -3349,10 +3381,13 @@ index_set_state_flags(Oid indexId, IndexStateFlagsAction action)
 			 * CONCURRENTLY that failed partway through.)
 			 *
 			 * Note: the CLUSTER logic assumes that indisclustered cannot be
-			 * set on any invalid index, so clear that flag too.
+			 * set on any invalid index, so clear that flag too.  Similarly,
+			 * ALTER TABLE assumes that indisreplident cannot be set for
+			 * invalid indexes.
 			 */
 			indexForm->indisvalid = false;
 			indexForm->indisclustered = false;
+			indexForm->indisreplident = false;
 			break;
 		case INDEX_DROP_SET_DEAD:
 
@@ -3364,6 +3399,8 @@ index_set_state_flags(Oid indexId, IndexStateFlagsAction action)
 			 * the index at all.
 			 */
 			Assert(!indexForm->indisvalid);
+			Assert(!indexForm->indisclustered);
+			Assert(!indexForm->indisreplident);
 			indexForm->indisready = false;
 			indexForm->indislive = false;
 			break;
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index d2b15a3387..968cb41f98 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -3020,6 +3020,41 @@ SetRelationHasSubclass(Oid relationId, bool relhassubclass)
 	table_close(relationRelation, RowExclusiveLock);
 }
 
+/*
+ * SetRelationReplIdent
+ *		Set the value of the relation's relreplident field in pg_class.
+ *
+ * NOTE: caller must be holding an appropriate lock on the relation.
+ * ShareUpdateExclusiveLock is sufficient.
+ */
+void
+SetRelationReplIdent(Oid relationId, char ri_type)
+{
+	Relation	relationRelation;
+	HeapTuple	tuple;
+	Form_pg_class classtuple;
+
+	/*
+	 * Fetch a modifiable copy of the tuple, modify it, update pg_class.
+	 */
+	relationRelation = table_open(RelationRelationId, RowExclusiveLock);
+	tuple = SearchSysCacheCopy1(RELOID,
+								ObjectIdGetDatum(relationId));
+	if (!HeapTupleIsValid(tuple))
+		elog(ERROR, "cache lookup failed for relation \"%s\"",
+			 get_rel_name(relationId));
+	classtuple = (Form_pg_class) GETSTRUCT(tuple);
+
+	if (classtuple->relreplident != ri_type)
+	{
+		classtuple->relreplident = ri_type;
+		CatalogTupleUpdate(relationRelation, &tuple->t_self, tuple);
+	}
+
+	heap_freetuple(tuple);
+	table_close(relationRelation, RowExclusiveLock);
+}
+
 /*
  *		renameatt_check			- basic sanity checks before attribute rename
  */
@@ -14487,31 +14522,12 @@ relation_mark_replica_identity(Relation rel, char ri_type, Oid indexOid,
 							   bool is_internal)
 {
 	Relation	pg_index;
-	Relation	pg_class;
-	HeapTuple	pg_class_tuple;
 	HeapTuple	pg_index_tuple;
-	Form_pg_class pg_class_form;
 	Form_pg_index pg_index_form;
-
 	ListCell   *index;
 
-	/*
-	 * Check whether relreplident has changed, and update it if so.
-	 */
-	pg_class = table_open(RelationRelationId, RowExclusiveLock);
-	pg_class_tuple = SearchSysCacheCopy1(RELOID,
-										 ObjectIdGetDatum(RelationGetRelid(rel)));
-	if (!HeapTupleIsValid(pg_class_tuple))
-		elog(ERROR, "cache lookup failed for relation \"%s\"",
-			 RelationGetRelationName(rel));
-	pg_class_form = (Form_pg_class) GETSTRUCT(pg_class_tuple);
-	if (pg_class_form->relreplident != ri_type)
-	{
-		pg_class_form->relreplident = ri_type;
-		CatalogTupleUpdate(pg_class, &pg_class_tuple->t_self, pg_class_tuple);
-	}
-	table_close(pg_class, RowExclusiveLock);
-	heap_freetuple(pg_class_tuple);
+	/* update relreplident if necessary */
+	SetRelationReplIdent(RelationGetRelid(rel), ri_type);
 
 	/*
 	 * Check whether the correct index is marked indisreplident; if so, we're
diff --git a/src/test/regress/expected/replica_identity.out b/src/test/regress/expected/replica_identity.out
index 79002197a7..86053c5bb4 100644
--- a/src/test/regress/expected/replica_identity.out
+++ b/src/test/regress/expected/replica_identity.out
@@ -227,3 +227,33 @@ DROP TABLE test_replica_identity;
 DROP TABLE test_replica_identity2;
 DROP TABLE test_replica_identity3;
 DROP TABLE test_replica_identity_othertable;
+--
+-- Test that DROP INDEX on a index used for REPLICA IDENTITY sets
+-- relreplident back to NOTHING.
+--
+CREATE TABLE test_replica_identity_4 (id int NOT NULL);
+CREATE UNIQUE INDEX test_replica_index_4 ON test_replica_identity_4(id);
+ALTER TABLE test_replica_identity_4 REPLICA IDENTITY
+  USING INDEX test_replica_index_4;
+DROP INDEX CONCURRENTLY test_replica_index_4;
+SELECT relreplident FROM pg_class WHERE oid = 'test_replica_identity_4'::regclass;
+ relreplident 
+--------------
+ n
+(1 row)
+
+DROP TABLE test_replica_identity_4;
+-- Partitioned table
+CREATE TABLE test_replica_part (id int NOT NULL)
+  PARTITION BY RANGE (id);
+CREATE UNIQUE INDEX test_replica_part_index ON test_replica_part(id);
+ALTER TABLE test_replica_part REPLICA IDENTITY
+  USING INDEX test_replica_part_index;
+DROP INDEX test_replica_part_index;
+SELECT relreplident FROM pg_class WHERE oid = 'test_replica_part'::regclass;
+ relreplident 
+--------------
+ n
+(1 row)
+
+DROP TABLE test_replica_part;
diff --git a/src/test/regress/sql/replica_identity.sql b/src/test/regress/sql/replica_identity.sql
index a5ac8f5567..6dd34dc39d 100644
--- a/src/test/regress/sql/replica_identity.sql
+++ b/src/test/regress/sql/replica_identity.sql
@@ -98,3 +98,25 @@ DROP TABLE test_replica_identity;
 DROP TABLE test_replica_identity2;
 DROP TABLE test_replica_identity3;
 DROP TABLE test_replica_identity_othertable;
+
+--
+-- Test that DROP INDEX on a index used for REPLICA IDENTITY sets
+-- relreplident back to NOTHING.
+--
+
+CREATE TABLE test_replica_identity_4 (id int NOT NULL);
+CREATE UNIQUE INDEX test_replica_index_4 ON test_replica_identity_4(id);
+ALTER TABLE test_replica_identity_4 REPLICA IDENTITY
+  USING INDEX test_replica_index_4;
+DROP INDEX CONCURRENTLY test_replica_index_4;
+SELECT relreplident FROM pg_class WHERE oid = 'test_replica_identity_4'::regclass;
+DROP TABLE test_replica_identity_4;
+-- Partitioned table
+CREATE TABLE test_replica_part (id int NOT NULL)
+  PARTITION BY RANGE (id);
+CREATE UNIQUE INDEX test_replica_part_index ON test_replica_part(id);
+ALTER TABLE test_replica_part REPLICA IDENTITY
+  USING INDEX test_replica_part_index;
+DROP INDEX test_replica_part_index;
+SELECT relreplident FROM pg_class WHERE oid = 'test_replica_part'::regclass;
+DROP TABLE test_replica_part;
diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index 9fe260ecff..601b3d448c 100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -2144,8 +2144,7 @@ SCRAM-SHA-256$<replaceable>&lt;iteration count&gt;</replaceable>:<replaceable>&l
        <literal>n</literal> = nothing,
        <literal>f</literal> = all columns,
        <literal>i</literal> = index with
-       <structfield>indisreplident</structfield> set (same as nothing if the
-       index used has been dropped)
+       <structfield>indisreplident</structfield> set
       </para></entry>
      </row>
 
-- 
2.28.0

From fa7585609a614bdba27bc2e3199379d04fc0eabd Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Sun, 30 Aug 2020 16:02:32 +0900
Subject: [PATCH v5] Reset pg_class.relreplident when associated replica index
 is dropped

When an index associated to REPLICA IDENTITY USING INDEX gets dropped,
relreplident gets set to 'i', which can be confusing as the catalogs
have a state inconsistent with pg_index that lacks an associated entry
marked with indisreplident.  This changes the logic so as such an index
dropped leads to 'n' to be set for the parent table, equivalent to
REPLICA IDENTITY NOTHING.

Author: Michael Paquier
Reviewed-by: Masahiko Sawada, Rahila Syed, Euler Taveira
Discussion: https://postgr.es/m/20200522035028.GO2355@paquier.xyz
---
 src/include/catalog/pg_class.h                |  6 +-
 src/include/commands/tablecmds.h              |  2 +
 src/backend/catalog/index.c                   | 37 +++++++++++-
 src/backend/commands/tablecmds.c              | 58 ++++++++++++-------
 .../regress/expected/replica_identity.out     | 30 ++++++++++
 src/test/regress/sql/replica_identity.sql     | 22 +++++++
 doc/src/sgml/catalogs.sgml                    |  3 +-
 7 files changed, 128 insertions(+), 30 deletions(-)

diff --git a/src/include/catalog/pg_class.h b/src/include/catalog/pg_class.h
index 78b33b2a7f..4f9ce17651 100644
--- a/src/include/catalog/pg_class.h
+++ b/src/include/catalog/pg_class.h
@@ -175,11 +175,7 @@ typedef FormData_pg_class *Form_pg_class;
 #define		  REPLICA_IDENTITY_NOTHING	'n'
 /* all columns are logged as replica identity */
 #define		  REPLICA_IDENTITY_FULL		'f'
-/*
- * an explicitly chosen candidate key's columns are used as replica identity.
- * Note this will still be set if the index has been dropped; in that case it
- * has the same meaning as 'd'.
- */
+/* an explicitly-chosen candidate key's columns are used as replica identity */
 #define		  REPLICA_IDENTITY_INDEX	'i'
 
 /*
diff --git a/src/include/commands/tablecmds.h b/src/include/commands/tablecmds.h
index c1581ad178..b163a82c52 100644
--- a/src/include/commands/tablecmds.h
+++ b/src/include/commands/tablecmds.h
@@ -61,6 +61,8 @@ extern void ExecuteTruncateGuts(List *explicit_rels, List *relids, List *relids_
 
 extern void SetRelationHasSubclass(Oid relationId, bool relhassubclass);
 
+extern void SetRelationReplIdent(Oid relationId, char ri_type);
+
 extern ObjectAddress renameatt(RenameStmt *stmt);
 
 extern ObjectAddress RenameConstraint(RenameStmt *stmt);
diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index 62e487bb4c..61d05495b4 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -2005,6 +2005,7 @@ index_drop(Oid indexId, bool concurrent, bool concurrent_lock_mode)
 	Relation	indexRelation;
 	HeapTuple	tuple;
 	bool		hasexprs;
+	bool		resetreplident;
 	LockRelId	heaprelid,
 				indexrelid;
 	LOCKTAG		heaplocktag;
@@ -2048,6 +2049,15 @@ index_drop(Oid indexId, bool concurrent, bool concurrent_lock_mode)
 	 */
 	CheckTableNotInUse(userIndexRelation, "DROP INDEX");
 
+	/*
+	 * Check if the REPLICA IDENTITY of the parent relation needs to be
+	 * reset.  This should be done only if the index to drop here is
+	 * marked as used in a replica identity.  We cannot rely on the
+	 * contents of pg_index for the index as a concurrent drop would have
+	 * reset indisreplident already, so save the existing value first.
+	 */
+	resetreplident = userIndexRelation->rd_index->indisreplident;
+
 	/*
 	 * Drop Index Concurrently is more or less the reverse process of Create
 	 * Index Concurrently.
@@ -2132,7 +2142,29 @@ index_drop(Oid indexId, bool concurrent, bool concurrent_lock_mode)
 		 */
 		LockRelationIdForSession(&heaprelid, ShareUpdateExclusiveLock);
 		LockRelationIdForSession(&indexrelid, ShareUpdateExclusiveLock);
+	}
 
+	/*
+	 * If the index to be dropped was marked as indisreplident (note that it
+	 * would have been reset when clearing indisvalid previously), reset
+	 * pg_class.relreplident for the parent table.  Note that this part
+	 * needs to be done in the same transaction as the one marking the
+	 * index as invalid, so as we never finish with the case where the
+	 * parent relation uses REPLICA_IDENTITY_INDEX, without any index marked
+	 * with indisreplident.
+	 */
+	if (resetreplident)
+	{
+		SetRelationReplIdent(heapId, REPLICA_IDENTITY_NOTHING);
+
+		/* make the update visible, only for the non-concurrent case */
+		if (!concurrent)
+			CommandCounterIncrement();
+	}
+
+	/* continue the concurrent process */
+	if (concurrent)
+	{
 		PopActiveSnapshot();
 		CommitTransactionCommand();
 		StartTransactionCommand();
@@ -2161,8 +2193,9 @@ index_drop(Oid indexId, bool concurrent, bool concurrent_lock_mode)
 		index_concurrently_set_dead(heapId, indexId);
 
 		/*
-		 * Again, commit the transaction to make the pg_index update visible
-		 * to other sessions.
+		 * Again, commit the transaction to make the pg_index and pg_class
+		 * (in the case where indisreplident is set) updates are visible to
+		 * other sessions.
 		 */
 		CommitTransactionCommand();
 		StartTransactionCommand();
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index d2b15a3387..968cb41f98 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -3020,6 +3020,41 @@ SetRelationHasSubclass(Oid relationId, bool relhassubclass)
 	table_close(relationRelation, RowExclusiveLock);
 }
 
+/*
+ * SetRelationReplIdent
+ *		Set the value of the relation's relreplident field in pg_class.
+ *
+ * NOTE: caller must be holding an appropriate lock on the relation.
+ * ShareUpdateExclusiveLock is sufficient.
+ */
+void
+SetRelationReplIdent(Oid relationId, char ri_type)
+{
+	Relation	relationRelation;
+	HeapTuple	tuple;
+	Form_pg_class classtuple;
+
+	/*
+	 * Fetch a modifiable copy of the tuple, modify it, update pg_class.
+	 */
+	relationRelation = table_open(RelationRelationId, RowExclusiveLock);
+	tuple = SearchSysCacheCopy1(RELOID,
+								ObjectIdGetDatum(relationId));
+	if (!HeapTupleIsValid(tuple))
+		elog(ERROR, "cache lookup failed for relation \"%s\"",
+			 get_rel_name(relationId));
+	classtuple = (Form_pg_class) GETSTRUCT(tuple);
+
+	if (classtuple->relreplident != ri_type)
+	{
+		classtuple->relreplident = ri_type;
+		CatalogTupleUpdate(relationRelation, &tuple->t_self, tuple);
+	}
+
+	heap_freetuple(tuple);
+	table_close(relationRelation, RowExclusiveLock);
+}
+
 /*
  *		renameatt_check			- basic sanity checks before attribute rename
  */
@@ -14487,31 +14522,12 @@ relation_mark_replica_identity(Relation rel, char ri_type, Oid indexOid,
 							   bool is_internal)
 {
 	Relation	pg_index;
-	Relation	pg_class;
-	HeapTuple	pg_class_tuple;
 	HeapTuple	pg_index_tuple;
-	Form_pg_class pg_class_form;
 	Form_pg_index pg_index_form;
-
 	ListCell   *index;
 
-	/*
-	 * Check whether relreplident has changed, and update it if so.
-	 */
-	pg_class = table_open(RelationRelationId, RowExclusiveLock);
-	pg_class_tuple = SearchSysCacheCopy1(RELOID,
-										 ObjectIdGetDatum(RelationGetRelid(rel)));
-	if (!HeapTupleIsValid(pg_class_tuple))
-		elog(ERROR, "cache lookup failed for relation \"%s\"",
-			 RelationGetRelationName(rel));
-	pg_class_form = (Form_pg_class) GETSTRUCT(pg_class_tuple);
-	if (pg_class_form->relreplident != ri_type)
-	{
-		pg_class_form->relreplident = ri_type;
-		CatalogTupleUpdate(pg_class, &pg_class_tuple->t_self, pg_class_tuple);
-	}
-	table_close(pg_class, RowExclusiveLock);
-	heap_freetuple(pg_class_tuple);
+	/* update relreplident if necessary */
+	SetRelationReplIdent(RelationGetRelid(rel), ri_type);
 
 	/*
 	 * Check whether the correct index is marked indisreplident; if so, we're
diff --git a/src/test/regress/expected/replica_identity.out b/src/test/regress/expected/replica_identity.out
index 79002197a7..86053c5bb4 100644
--- a/src/test/regress/expected/replica_identity.out
+++ b/src/test/regress/expected/replica_identity.out
@@ -227,3 +227,33 @@ DROP TABLE test_replica_identity;
 DROP TABLE test_replica_identity2;
 DROP TABLE test_replica_identity3;
 DROP TABLE test_replica_identity_othertable;
+--
+-- Test that DROP INDEX on a index used for REPLICA IDENTITY sets
+-- relreplident back to NOTHING.
+--
+CREATE TABLE test_replica_identity_4 (id int NOT NULL);
+CREATE UNIQUE INDEX test_replica_index_4 ON test_replica_identity_4(id);
+ALTER TABLE test_replica_identity_4 REPLICA IDENTITY
+  USING INDEX test_replica_index_4;
+DROP INDEX CONCURRENTLY test_replica_index_4;
+SELECT relreplident FROM pg_class WHERE oid = 'test_replica_identity_4'::regclass;
+ relreplident 
+--------------
+ n
+(1 row)
+
+DROP TABLE test_replica_identity_4;
+-- Partitioned table
+CREATE TABLE test_replica_part (id int NOT NULL)
+  PARTITION BY RANGE (id);
+CREATE UNIQUE INDEX test_replica_part_index ON test_replica_part(id);
+ALTER TABLE test_replica_part REPLICA IDENTITY
+  USING INDEX test_replica_part_index;
+DROP INDEX test_replica_part_index;
+SELECT relreplident FROM pg_class WHERE oid = 'test_replica_part'::regclass;
+ relreplident 
+--------------
+ n
+(1 row)
+
+DROP TABLE test_replica_part;
diff --git a/src/test/regress/sql/replica_identity.sql b/src/test/regress/sql/replica_identity.sql
index a5ac8f5567..6dd34dc39d 100644
--- a/src/test/regress/sql/replica_identity.sql
+++ b/src/test/regress/sql/replica_identity.sql
@@ -98,3 +98,25 @@ DROP TABLE test_replica_identity;
 DROP TABLE test_replica_identity2;
 DROP TABLE test_replica_identity3;
 DROP TABLE test_replica_identity_othertable;
+
+--
+-- Test that DROP INDEX on a index used for REPLICA IDENTITY sets
+-- relreplident back to NOTHING.
+--
+
+CREATE TABLE test_replica_identity_4 (id int NOT NULL);
+CREATE UNIQUE INDEX test_replica_index_4 ON test_replica_identity_4(id);
+ALTER TABLE test_replica_identity_4 REPLICA IDENTITY
+  USING INDEX test_replica_index_4;
+DROP INDEX CONCURRENTLY test_replica_index_4;
+SELECT relreplident FROM pg_class WHERE oid = 'test_replica_identity_4'::regclass;
+DROP TABLE test_replica_identity_4;
+-- Partitioned table
+CREATE TABLE test_replica_part (id int NOT NULL)
+  PARTITION BY RANGE (id);
+CREATE UNIQUE INDEX test_replica_part_index ON test_replica_part(id);
+ALTER TABLE test_replica_part REPLICA IDENTITY
+  USING INDEX test_replica_part_index;
+DROP INDEX test_replica_part_index;
+SELECT relreplident FROM pg_class WHERE oid = 'test_replica_part'::regclass;
+DROP TABLE test_replica_part;
diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index 9fe260ecff..601b3d448c 100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -2144,8 +2144,7 @@ SCRAM-SHA-256$<replaceable>&lt;iteration count&gt;</replaceable>:<replaceable>&l
        <literal>n</literal> = nothing,
        <literal>f</literal> = all columns,
        <literal>i</literal> = index with
-       <structfield>indisreplident</structfield> set (same as nothing if the
-       index used has been dropped)
+       <structfield>indisreplident</structfield> set
       </para></entry>
      </row>
 
-- 
2.28.0