From ec7f9a7407d3f6e0d27033b026bcb966eebe8e71 Mon Sep 17 00:00:00 2001 From: Alvaro Herrera Date: Tue, 23 Jul 2019 17:22:15 -0400 Subject: [PATCH] Check that partitions are not in use when dropping constraints If the user creates a deferred constraint in a partition, and in a transaction they cause the constraint's trigger execution to be deferred until commit time *and* drop the constraint, then when commit time comes the queued trigger will fail to run because the trigger object will have been dropped. This is explained because when a constraint gets dropped in a partitioned table, the recursion to drop the ones in partitions is done by the dependency mechanism, not by ALTER TABLE traversing the recursion tree as in all other cases. In the non-partitioned case, this problem is avoided by checking that the table is not "in use" by alter-table; other alter-table subcommands that recurse to partitions do that check for each partition. But the dependency mechanism doesn't have a way to do that. Fix the problem by applying the same check to all partitions during ALTER TABLE's "prep" phase, which correctly raises the necessary error. Reported-by: Rajkumar Raghuwanshi Discussion: https://postgr.es/m/CAKcux6nZiO9-eEpr1ZD84bT1mBoVmeZkfont8iSpcmYrjhGWgA@mail.gmail.com --- src/backend/commands/tablecmds.c | 56 ++++++++++++++++++----- src/test/regress/expected/foreign_key.out | 15 +++++- src/test/regress/sql/foreign_key.sql | 13 +++++- 3 files changed, 70 insertions(+), 14 deletions(-) diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 2ceda4f0a16..836e0845c0d 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -353,6 +353,7 @@ static void ATSimplePermissions(Relation rel, int allowed_targets); static void ATWrongRelkindError(Relation rel, int allowed_targets); static void ATSimpleRecursion(List **wqueue, Relation rel, AlterTableCmd *cmd, bool recurse, LOCKMODE lockmode); +static void ATCheckPartitionsNotInUse(Relation rel, LOCKMODE lockmode); static void ATTypedTableRecursion(List **wqueue, Relation rel, AlterTableCmd *cmd, LOCKMODE lockmode); static List *find_typed_table_dependencies(Oid typeOid, const char *typeName, @@ -3269,8 +3270,7 @@ CheckTableNotInUse(Relation rel, const char *stmt) ereport(ERROR, (errcode(ERRCODE_OBJECT_IN_USE), /* translator: first %s is a SQL command, eg ALTER TABLE */ - errmsg("cannot %s \"%s\" because " - "it is being used by active queries in this session", + errmsg("cannot %s \"%s\" because it is being used by active queries in this session", stmt, RelationGetRelationName(rel)))); if (rel->rd_rel->relkind != RELKIND_INDEX && @@ -3279,8 +3279,7 @@ CheckTableNotInUse(Relation rel, const char *stmt) ereport(ERROR, (errcode(ERRCODE_OBJECT_IN_USE), /* translator: first %s is a SQL command, eg ALTER TABLE */ - errmsg("cannot %s \"%s\" because " - "it has pending trigger events", + errmsg("cannot %s \"%s\" because it has pending trigger events", stmt, RelationGetRelationName(rel)))); } @@ -3746,16 +3745,19 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd, break; case AT_AddIdentity: ATSimplePermissions(rel, ATT_TABLE | ATT_VIEW | ATT_FOREIGN_TABLE); + /* This command never recurses */ pass = AT_PASS_ADD_CONSTR; break; - case AT_DropIdentity: - ATSimplePermissions(rel, ATT_TABLE | ATT_VIEW | ATT_FOREIGN_TABLE); - pass = AT_PASS_DROP; - break; case AT_SetIdentity: ATSimplePermissions(rel, ATT_TABLE | ATT_VIEW | ATT_FOREIGN_TABLE); + /* This command never recurses */ pass = AT_PASS_COL_ATTRS; break; + case AT_DropIdentity: + ATSimplePermissions(rel, ATT_TABLE | ATT_VIEW | ATT_FOREIGN_TABLE); + /* This command never recurses */ + pass = AT_PASS_DROP; + break; case AT_DropNotNull: /* ALTER COLUMN DROP NOT NULL */ ATSimplePermissions(rel, ATT_TABLE | ATT_FOREIGN_TABLE); ATPrepDropNotNull(rel, recurse, recursing); @@ -3817,7 +3819,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd, break; case AT_DropConstraint: /* DROP CONSTRAINT */ ATSimplePermissions(rel, ATT_TABLE | ATT_FOREIGN_TABLE); - /* Recursion occurs during execution phase */ + ATCheckPartitionsNotInUse(rel, lockmode); + /* Other recursion occurs during execution phase */ /* No command-specific prep needed except saving recurse flag */ if (recurse) cmd->subtype = AT_DropConstraintRecurse; @@ -5085,8 +5088,9 @@ ATSimpleRecursion(List **wqueue, Relation rel, AlterTableCmd *cmd, bool recurse, LOCKMODE lockmode) { /* - * Propagate to children if desired. Only plain tables and foreign tables - * have children, so no need to search for other relkinds. + * Propagate to children if desired. Only plain tables, foreign tables + * and partitioned tables have children, so no need to search for other + * relkinds. */ if (recurse && (rel->rd_rel->relkind == RELKIND_RELATION || @@ -5120,6 +5124,36 @@ ATSimpleRecursion(List **wqueue, Relation rel, } } +/* + * Obtain list of partitions of the given table, locking them all at the given + * lockmode and ensuring that they all pass CheckTableNotInUse. + * + * This function is a no-op if the given relation is not a partitioned table; + * in particular, nothing is done if it's a legacy inheritance parent. + */ +static void +ATCheckPartitionsNotInUse(Relation rel, LOCKMODE lockmode) +{ + if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE) + { + List *inh; + ListCell *cell; + + inh = find_all_inheritors(RelationGetRelid(rel), lockmode, NULL); + /* first element is the parent rel; must ignore it */ + for_each_cell(cell, lnext(list_head(inh))) + { + Relation childrel; + + /* find_all_inheritors already got lock */ + childrel = heap_open(lfirst_oid(cell), NoLock); + CheckTableNotInUse(childrel, "ALTER TABLE"); + heap_close(childrel, NoLock); + } + list_free(inh); + } +} + /* * ATTypedTableRecursion * diff --git a/src/test/regress/expected/foreign_key.out b/src/test/regress/expected/foreign_key.out index d283ca661a7..754a9d5ae1b 100644 --- a/src/test/regress/expected/foreign_key.out +++ b/src/test/regress/expected/foreign_key.out @@ -1926,7 +1926,18 @@ alter table fkpart2.fk_part detach partition fkpart2.fk_part_1; alter table fkpart2.fk_part_1 drop constraint fkey; -- ok alter table fkpart2.fk_part_1_1 drop constraint my_fkey; -- doesn't exist ERROR: constraint "my_fkey" of relation "fk_part_1_1" does not exist +-- ensure we check partitions are "not used" when dropping constraints +CREATE SCHEMA fkpart8 + CREATE TABLE tbl1(f1 int PRIMARY KEY) + CREATE TABLE tbl2(f1 int REFERENCES tbl1 DEFERRABLE INITIALLY DEFERRED) PARTITION BY RANGE(f1) + CREATE TABLE tbl2_p1 PARTITION OF tbl2 FOR VALUES FROM (minvalue) TO (maxvalue); +INSERT INTO fkpart8.tbl1 VALUES(1); +BEGIN; +INSERT INTO fkpart8.tbl2 VALUES(1); +ALTER TABLE fkpart8.tbl2 DROP CONSTRAINT tbl2_f1_fkey; +ERROR: cannot ALTER TABLE "tbl2_p1" because it has pending trigger events +COMMIT; \set VERBOSITY terse \\ -- suppress cascade details -drop schema fkpart0, fkpart1, fkpart2 cascade; -NOTICE: drop cascades to 8 other objects +drop schema fkpart0, fkpart1, fkpart2, fkpart8 cascade; +NOTICE: drop cascades to 10 other objects \set VERBOSITY default diff --git a/src/test/regress/sql/foreign_key.sql b/src/test/regress/sql/foreign_key.sql index 2dcbfe4cf8c..3f8e9b83d34 100644 --- a/src/test/regress/sql/foreign_key.sql +++ b/src/test/regress/sql/foreign_key.sql @@ -1380,6 +1380,17 @@ alter table fkpart2.fk_part detach partition fkpart2.fk_part_1; alter table fkpart2.fk_part_1 drop constraint fkey; -- ok alter table fkpart2.fk_part_1_1 drop constraint my_fkey; -- doesn't exist +-- ensure we check partitions are "not used" when dropping constraints +CREATE SCHEMA fkpart8 + CREATE TABLE tbl1(f1 int PRIMARY KEY) + CREATE TABLE tbl2(f1 int REFERENCES tbl1 DEFERRABLE INITIALLY DEFERRED) PARTITION BY RANGE(f1) + CREATE TABLE tbl2_p1 PARTITION OF tbl2 FOR VALUES FROM (minvalue) TO (maxvalue); +INSERT INTO fkpart8.tbl1 VALUES(1); +BEGIN; +INSERT INTO fkpart8.tbl2 VALUES(1); +ALTER TABLE fkpart8.tbl2 DROP CONSTRAINT tbl2_f1_fkey; +COMMIT; + \set VERBOSITY terse \\ -- suppress cascade details -drop schema fkpart0, fkpart1, fkpart2 cascade; +drop schema fkpart0, fkpart1, fkpart2, fkpart8 cascade; \set VERBOSITY default -- 2.39.5