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Make identity sequence management more robust 

Some code could get confused when certain catalog state involving both
identity and serial sequences was present, perhaps during an attempt
to upgrade the latter to the former.  Specifically, dropping the
default of a serial column maintains the ownership of the sequence by
the column, and so it would then be possible to afterwards make the
column an identity column that would now own two sequences.  This
causes the code that looks up the identity sequence to error out,
making the new identity column inoperable until the ownership of the
previous sequence is released.

To fix this, make the identity sequence lookup only consider sequences
with the appropriate dependency type for an identity sequence, so it
only ever finds one (unless something else is broken).  In the above
example, the old serial sequence would then be ignored.  Reorganize
the various owned-sequence-lookup functions a bit to make this
clearer.

Reported-by: Laurenz Albe <laurenz.albe@cybertec.at>
Discussion: https://www.postgresql.org/message-id/flat/470c54fc8590be4de0f41b0d295fd6390d5e8a6c.camel@cybertec.at
This commit is contained in:
Peter Eisentraut 2019-07-22 12:05:03 +02:00
parent efdcca55a3
commit 19781729f7
7 changed files with 48 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

33
src/backend/catalog/pg_depend.c
View File

@ -705,10 +705,11 @@ sequenceIsOwned(Oid seqId, char deptype, Oid *tableId, int32 *colId)
/*
* Collect a list of OIDs of all sequences owned by the specified relation,
* and column if specified.
* and column if specified. If deptype is not zero, then only find sequences
* with the specified dependency type.
*/
List *
getOwnedSequences(Oid relid, AttrNumber attnum)
static List *
getOwnedSequences_internal(Oid relid, AttrNumber attnum, char deptype)
{
List *result = NIL;
Relation depRel;
@ -750,7 +751,8 @@ getOwnedSequences(Oid relid, AttrNumber attnum)
(deprec->deptype == DEPENDENCY_AUTO || deprec->deptype == DEPENDENCY_INTERNAL) &&
get_rel_relkind(deprec->objid) == RELKIND_SEQUENCE)
{
result = lappend_oid(result, deprec->objid);
if (!deptype || deprec->deptype == deptype)
result = lappend_oid(result, deprec->objid);
}
}
@ -762,17 +764,32 @@ getOwnedSequences(Oid relid, AttrNumber attnum)
}
/*
* Get owned sequence, error if not exactly one.
* Collect a list of OIDs of all sequences owned (identity or serial) by the
* specified relation.
*/
List *
getOwnedSequences(Oid relid)
{
return getOwnedSequences_internal(relid, 0, 0);
}
/*
* Get owned identity sequence, error if not exactly one.
*/
Oid
getOwnedSequence(Oid relid, AttrNumber attnum)
getIdentitySequence(Oid relid, AttrNumber attnum, bool missing_ok)
{
List *seqlist = getOwnedSequences(relid, attnum);
List *seqlist = getOwnedSequences_internal(relid, attnum, DEPENDENCY_INTERNAL);
if (list_length(seqlist) > 1)
elog(ERROR, "more than one owned sequence found");
else if (list_length(seqlist) < 1)
elog(ERROR, "no owned sequence found");
{
if (missing_ok)
return InvalidOid;
else
elog(ERROR, "no owned sequence found");
}
return linitial_oid(seqlist);
}

4
src/backend/commands/tablecmds.c
View File

@ -1689,7 +1689,7 @@ ExecuteTruncateGuts(List *explicit_rels, List *relids, List *relids_logged,
foreach(cell, rels)
{
Relation rel = (Relation) lfirst(cell);
List *seqlist = getOwnedSequences(RelationGetRelid(rel), 0);
List *seqlist = getOwnedSequences(RelationGetRelid(rel));
ListCell *seqcell;
foreach(seqcell, seqlist)
@ -6635,7 +6635,7 @@ ATExecDropIdentity(Relation rel, const char *colName, bool missing_ok, LOCKMODE
table_close(attrelation, RowExclusiveLock);
/* drop the internal sequence */
seqid = getOwnedSequence(RelationGetRelid(rel), attnum);
seqid = getIdentitySequence(RelationGetRelid(rel), attnum, false);
deleteDependencyRecordsForClass(RelationRelationId, seqid,
RelationRelationId, DEPENDENCY_INTERNAL);
CommandCounterIncrement();

12
src/backend/parser/parse_utilcmd.c
View File

@ -1083,7 +1083,7 @@ transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_cla
* find sequence owned by old column; extract sequence parameters;
* build new create sequence command
*/
seq_relid = getOwnedSequence(RelationGetRelid(relation), attribute->attnum);
seq_relid = getIdentitySequence(RelationGetRelid(relation), attribute->attnum, false);
seq_options = sequence_options(seq_relid);
generateSerialExtraStmts(cxt, def,
InvalidOid, seq_options, true,
@ -3165,7 +3165,7 @@ transformAlterTableStmt(Oid relid, AlterTableStmt *stmt,
if (attnum != InvalidAttrNumber &&
TupleDescAttr(tupdesc, attnum - 1)->attidentity)
{
Oid seq_relid = getOwnedSequence(relid, attnum);
Oid seq_relid = getIdentitySequence(relid, attnum, false);
Oid typeOid = typenameTypeId(pstate, def->typeName);
AlterSeqStmt *altseqstmt = makeNode(AlterSeqStmt);
@ -3216,7 +3216,6 @@ transformAlterTableStmt(Oid relid, AlterTableStmt *stmt,
ListCell *lc;
List *newseqopts = NIL;
List *newdef = NIL;
List *seqlist;
AttrNumber attnum;
/*
@ -3237,14 +3236,13 @@ transformAlterTableStmt(Oid relid, AlterTableStmt *stmt,
if (attnum)
{
seqlist = getOwnedSequences(relid, attnum);
if (seqlist)
Oid seq_relid = getIdentitySequence(relid, attnum, true);
if (seq_relid)
{
AlterSeqStmt *seqstmt;
Oid seq_relid;
seqstmt = makeNode(AlterSeqStmt);
seq_relid = linitial_oid(seqlist);
seqstmt->sequence = makeRangeVar(get_namespace_name(get_rel_namespace(seq_relid)),
get_rel_name(seq_relid), -1);
seqstmt->options = newseqopts;

2
src/backend/rewrite/rewriteHandler.c
View File

@ -1130,7 +1130,7 @@ build_column_default(Relation rel, int attrno)
{
NextValueExpr *nve = makeNode(NextValueExpr);
nve->seqid = getOwnedSequence(RelationGetRelid(rel), attrno);
nve->seqid = getIdentitySequence(RelationGetRelid(rel), attrno, false);
nve->typeId = att_tup->atttypid;
return (Node *) nve;

4
src/include/catalog/dependency.h
View File

@ -209,8 +209,8 @@ extern long changeDependenciesOn(Oid refClassId, Oid oldRefObjectId,
extern Oid getExtensionOfObject(Oid classId, Oid objectId);
extern bool sequenceIsOwned(Oid seqId, char deptype, Oid *tableId, int32 *colId);
extern List *getOwnedSequences(Oid relid, AttrNumber attnum);
extern Oid getOwnedSequence(Oid relid, AttrNumber attnum);
extern List *getOwnedSequences(Oid relid);
extern Oid getIdentitySequence(Oid relid, AttrNumber attnum, bool missing_ok);
extern Oid get_constraint_index(Oid constraintId);

5
src/test/regress/expected/identity.out
View File

@ -399,3 +399,8 @@ CREATE TABLE itest_child PARTITION OF itest_parent (
) FOR VALUES FROM ('2016-07-01') TO ('2016-08-01'); -- error
ERROR: identity columns are not supported on partitions
DROP TABLE itest_parent;
-- test that sequence of half-dropped serial column is properly ignored
CREATE TABLE itest14 (id serial);
ALTER TABLE itest14 ALTER id DROP DEFAULT;
ALTER TABLE itest14 ALTER id ADD GENERATED BY DEFAULT AS IDENTITY;
INSERT INTO itest14 (id) VALUES (DEFAULT);

8
src/test/regress/sql/identity.sql
View File

@ -254,3 +254,11 @@ CREATE TABLE itest_child PARTITION OF itest_parent (
f3 WITH OPTIONS GENERATED ALWAYS AS IDENTITY
) FOR VALUES FROM ('2016-07-01') TO ('2016-08-01'); -- error
DROP TABLE itest_parent;
-- test that sequence of half-dropped serial column is properly ignored
CREATE TABLE itest14 (id serial);
ALTER TABLE itest14 ALTER id DROP DEFAULT;
ALTER TABLE itest14 ALTER id ADD GENERATED BY DEFAULT AS IDENTITY;
INSERT INTO itest14 (id) VALUES (DEFAULT);