diff --git a/doc/src/sgml/ref/truncate.sgml b/doc/src/sgml/ref/truncate.sgml index f32d255..137eade 100644 *** a/doc/src/sgml/ref/truncate.sgml --- b/doc/src/sgml/ref/truncate.sgml *************** TRUNCATE [ TABLE ] [ ONLY ] - - - Any ALTER SEQUENCE RESTART operations performed as a - consequence of using the RESTART IDENTITY option are - nontransactional and will not be rolled back on failure. To minimize - the risk, these operations are performed only after all the rest of - TRUNCATE's work is done. However, there is still a risk - if TRUNCATE is performed inside a transaction block that is - aborted afterwards. For example, consider - - BEGIN; - TRUNCATE TABLE foo RESTART IDENTITY; - COPY foo FROM ...; - COMMIT; - - - If the COPY fails partway through, the table data - rolls back correctly, but the sequences will be left with values - that are probably smaller than they had before, possibly leading - to duplicate-key failures or other problems in later transactions. - If this is likely to be a problem, it's best to avoid using - RESTART IDENTITY, and accept that the new contents of - the table will have higher serial numbers than the old. - - --- 159,165 ---- diff --git a/src/backend/commands/sequence.c b/src/backend/commands/sequence.c index 04b0c71..4fb9093 100644 *** a/src/backend/commands/sequence.c --- b/src/backend/commands/sequence.c *************** *** 35,41 **** #include "utils/lsyscache.h" #include "utils/resowner.h" #include "utils/syscache.h" ! /* * We don't want to log each fetching of a value from a sequence, --- 35,41 ---- #include "utils/lsyscache.h" #include "utils/resowner.h" #include "utils/syscache.h" ! #include "utils/snapmgr.h" /* * We don't want to log each fetching of a value from a sequence, *************** static void init_params(List *options, b *** 96,101 **** --- 96,104 ---- static void do_setval(Oid relid, int64 next, bool iscalled); static void process_owned_by(Relation seqrel, List *owned_by); + static void init_seq_relation(Relation rel,TupleDesc tupDesc,Datum * value, + bool * null,List * owned_by); + /* * DefineSequence *************** DefineSequence(CreateSeqStmt *seq) *** 109,119 **** CreateStmt *stmt = makeNode(CreateStmt); Oid seqoid; Relation rel; ! Buffer buf; ! Page page; ! sequence_magic *sm; ! HeapTuple tuple; ! TupleDesc tupDesc; Datum value[SEQ_COL_LASTCOL]; bool null[SEQ_COL_LASTCOL]; int i; --- 112,118 ---- CreateStmt *stmt = makeNode(CreateStmt); Oid seqoid; Relation rel; ! TupleDesc tupDesc; Datum value[SEQ_COL_LASTCOL]; bool null[SEQ_COL_LASTCOL]; int i; *************** DefineSequence(CreateSeqStmt *seq) *** 210,217 **** rel = heap_open(seqoid, AccessExclusiveLock); tupDesc = RelationGetDescr(rel); ! /* Initialize first page of relation with special magic number */ buf = ReadBuffer(rel, P_NEW); Assert(BufferGetBlockNumber(buf) == 0); --- 209,293 ---- rel = heap_open(seqoid, AccessExclusiveLock); tupDesc = RelationGetDescr(rel); + init_seq_relation(rel, tupDesc,value,null,owned_by); + heap_close(rel, NoLock); + } ! /** ! * Resets the relation used by a sequence. ! * ! * The sequence is reset to its initial values, ! * the old sequence is left in place in case the ! * transaction rolls back. ! */ ! void ResetSequenceRelation(Oid seq_relid,List * options) ! { ! Relation seq_rel = relation_open(seq_relid,AccessExclusiveLock); ! SeqTable elm; ! Page page; ! Form_pg_sequence seq; ! Buffer buf; ! TupleDesc tupDesc; ! sequence_magic * sm; ! HeapTupleData tuple; ! ItemId lp; ! Datum * values; ! bool * isnull; ! ! /** ! * Read the old sequence. ! * ! */ ! init_sequence(seq_relid,&elm,&seq_rel); ! seq = read_info(elm,seq_rel,&buf); ! page = BufferGetPage(buf); ! sm = (sequence_magic *) PageGetSpecialPointer(page); ! ! if (sm->magic != SEQ_MAGIC) ! elog(ERROR, "bad magic number in sequence \"%s\": %08X", ! RelationGetRelationName(seq_rel), sm->magic); ! ! lp = PageGetItemId(page, FirstOffsetNumber); ! Assert(ItemIdIsNormal(lp)); ! ! tuple.t_data = (HeapTupleHeader) PageGetItem(page, lp); ! tupDesc = RelationGetDescr(seq_rel); ! values=palloc(sizeof(Datum)*tupDesc->natts); ! isnull=palloc(sizeof(bool)*tupDesc->natts); ! heap_deform_tuple(&tuple,tupDesc,values,isnull); ! UnlockReleaseBuffer(buf); ! relation_close(seq_rel,NoLock); ! ! /** ! * Get a new Relfilenode ! */ ! RelationSetNewRelfilenode(seq_rel,RecentXmin); ! ! /** ! * Add a tuple to the new refilenode. use the values ! * from the old version. ! */ ! init_seq_relation(seq_rel,tupDesc,values,isnull,NULL); ! pfree(values); ! pfree(isnull); ! /** ! * reset the sequence ! */ ! AlterSequenceInternal(seq_relid, options); ! relation_close(seq_rel,NoLock); ! ! } ! static void init_seq_relation(Relation rel,TupleDesc tupDesc,Datum *value, ! bool * null, List * owned_by) ! { ! Buffer buf; ! Page page; ! sequence_magic * sm; ! HeapTuple tuple; ! ! ! tupDesc = RelationGetDescr(rel); ! /* Initialize first page of relation with special magic number */ buf = ReadBuffer(rel, P_NEW); Assert(BufferGetBlockNumber(buf) == 0); *************** DefineSequence(CreateSeqStmt *seq) *** 311,317 **** if (owned_by) process_owned_by(rel, owned_by); ! heap_close(rel, NoLock); } /* --- 387,393 ---- if (owned_by) process_owned_by(rel, owned_by); ! } /* diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index c009711..04318f8 100644 *** a/src/backend/commands/tablecmds.c --- b/src/backend/commands/tablecmds.c *************** ExecuteTruncate(TruncateStmt *stmt) *** 816,822 **** { List *rels = NIL; List *relids = NIL; - List *seq_relids = NIL; EState *estate; ResultRelInfo *resultRelInfos; ResultRelInfo *resultRelInfo; --- 816,821 ---- *************** ExecuteTruncate(TruncateStmt *stmt) *** 923,949 **** */ if (stmt->restart_seqs) { foreach(cell, rels) { Relation rel = (Relation) lfirst(cell); List *seqlist = getOwnedSequences(RelationGetRelid(rel)); ListCell *seqcell; ! foreach(seqcell, seqlist) { Oid seq_relid = lfirst_oid(seqcell); ! Relation seq_rel; ! ! seq_rel = relation_open(seq_relid, AccessShareLock); ! /* This check must match AlterSequence! */ if (!pg_class_ownercheck(seq_relid, GetUserId())) aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_CLASS, RelationGetRelationName(seq_rel)); - - seq_relids = lappend_oid(seq_relids, seq_relid); - relation_close(seq_rel, NoLock); } } } --- 922,944 ---- */ if (stmt->restart_seqs) { + foreach(cell, rels) { Relation rel = (Relation) lfirst(cell); List *seqlist = getOwnedSequences(RelationGetRelid(rel)); ListCell *seqcell; ! List *options = list_make1(makeDefElem("restart", NULL)); foreach(seqcell, seqlist) { Oid seq_relid = lfirst_oid(seqcell); ! Relation seq_rel = relation_open(seq_relid, AccessShareLock); /* This check must match AlterSequence! */ if (!pg_class_ownercheck(seq_relid, GetUserId())) aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_CLASS, RelationGetRelationName(seq_rel)); relation_close(seq_rel, NoLock); + ResetSequenceRelation(seq_relid,options); } } } *************** ExecuteTruncate(TruncateStmt *stmt) *** 1068,1093 **** heap_close(rel, NoLock); } - /* - * Lastly, restart any owned sequences if we were asked to. This is done - * last because it's nontransactional: restarts will not roll back if we - * abort later. Hence it's important to postpone them as long as - * possible. (This is also a big reason why we locked and - * permission-checked the sequences beforehand.) - */ - if (stmt->restart_seqs) - { - List *options = list_make1(makeDefElem("restart", NULL)); - - foreach(cell, seq_relids) - { - Oid seq_relid = lfirst_oid(cell); - - AlterSequenceInternal(seq_relid, options); - } - } } /* * Check that a given rel is safe to truncate. Subroutine for ExecuteTruncate */ --- 1063,1071 ---- heap_close(rel, NoLock); } } + /* * Check that a given rel is safe to truncate. Subroutine for ExecuteTruncate */ diff --git a/src/include/commands/sequence.h b/src/include/commands/sequence.h index 5f566f6..3dab6db 100644 *** a/src/include/commands/sequence.h --- b/src/include/commands/sequence.h *************** extern Datum lastval(PG_FUNCTION_ARGS); *** 72,77 **** --- 72,78 ---- extern void DefineSequence(CreateSeqStmt *stmt); extern void AlterSequence(AlterSeqStmt *stmt); extern void AlterSequenceInternal(Oid relid, List *options); + extern void ResetSequenceRelation(Oid seq_relid,List * options); extern void seq_redo(XLogRecPtr lsn, XLogRecord *rptr); extern void seq_desc(StringInfo buf, uint8 xl_info, char *rec); diff --git a/src/test/regress/expected/truncate.out b/src/test/regress/expected/truncate.out index 7f43df7..169c53a 100644 *** a/src/test/regress/expected/truncate.out --- b/src/test/regress/expected/truncate.out *************** SELECT * FROM truncate_a; *** 398,403 **** --- 398,415 ---- 2 | 34 (2 rows) + BEGIN; + TRUNCATE truncate_a RESTART IDENTITY; + ROLLBACK; + INSERT INTO truncate_a DEFAULT VALUES; + SELECT * FROM truncate_a; + id | id1 + ----+----- + 1 | 33 + 2 | 34 + 3 | 35 + (3 rows) + DROP TABLE truncate_a; SELECT nextval('truncate_a_id1'); -- fail, seq should have been dropped ERROR: relation "truncate_a_id1" does not exist diff --git a/src/test/regress/sql/truncate.sql b/src/test/regress/sql/truncate.sql index b348e94..9c2c91a 100644 *** a/src/test/regress/sql/truncate.sql --- b/src/test/regress/sql/truncate.sql *************** INSERT INTO truncate_a DEFAULT VALUES; *** 202,207 **** --- 202,214 ---- INSERT INTO truncate_a DEFAULT VALUES; SELECT * FROM truncate_a; + BEGIN; + TRUNCATE truncate_a RESTART IDENTITY; + ROLLBACK; + INSERT INTO truncate_a DEFAULT VALUES; + SELECT * FROM truncate_a; + + DROP TABLE truncate_a; SELECT nextval('truncate_a_id1'); -- fail, seq should have been dropped