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Block creation of partitions with open references to its parent
When a partition is created as part of a trigger processing, it is possible that the partition which just gets created changes the properties of the table the executor of the ongoing command relies on, causing a subsequent crash. This has been found possible when for example using a BEFORE INSERT which creates a new partition for a partitioned table being inserted to. Any attempt to do so is blocked when working on a partition, with regression tests added for both CREATE TABLE PARTITION OF and ALTER TABLE ATTACH PARTITION. Reported-by: Dmitry Shalashov Author: Amit Langote Reviewed-by: Michael Paquier, Tom Lane Discussion: https://postgr.es/m/15437-3fe01ee66bd1bae1@postgresql.org Backpatch-through: 10
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‎src/backend/commands/tablecmds.c

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@@ -1750,6 +1750,14 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
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else
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relation = heap_openrv(parent, AccessExclusiveLock);
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/*
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* Check for active uses of the parent partitioned table in the
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* current transaction, such as being used in some manner by an
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* enclosing command.
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*/
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if (is_partition)
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CheckTableNotInUse(relation, "CREATE TABLE .. PARTITION OF");
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/*
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* We do not allow partitioned tables and partitions to participate in
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* regular inheritance.

‎src/test/regress/expected/alter_table.out

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@@ -3669,6 +3669,24 @@ alter table temp_part_parent attach partition temp_part_child
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for values in (1, 2); -- ok
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drop table perm_part_parent cascade;
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drop table temp_part_parent cascade;
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-- check that attaching partitions to a table while it is being used is
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-- prevented
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create table tab_part_attach (a int) partition by list (a);
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create or replace function func_part_attach() returns trigger
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language plpgsql as $$
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begin
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execute 'create table tab_part_attach_1 (a int)';
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execute 'alter table tab_part_attach attach partition tab_part_attach_1 for values in (1)';
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return null;
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end $$;
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create trigger trig_part_attach before insert on tab_part_attach
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for each statement execute procedure func_part_attach();
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insert into tab_part_attach values (1);
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ERROR: cannot ALTER TABLE "tab_part_attach" because it is being used by active queries in this session
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CONTEXT: SQL statement "alter table tab_part_attach attach partition tab_part_attach_1 for values in (1)"
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PL/pgSQL function func_part_attach() line 4 at EXECUTE
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drop table tab_part_attach;
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drop function func_part_attach();
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-- test case where the partitioning operator is a SQL function whose
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-- evaluation results in the table's relcache being rebuilt partway through
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-- the execution of an ATTACH PARTITION command

‎src/test/regress/expected/create_table.out

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@@ -830,3 +830,19 @@ ERROR: cannot create a temporary relation as partition of permanent relation "p
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create temp table temp_part partition of temp_parted for values in (1, 2); -- ok
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drop table perm_parted cascade;
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drop table temp_parted cascade;
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-- check that adding partitions to a table while it is being used is prevented
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create table tab_part_create (a int) partition by list (a);
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create or replace function func_part_create() returns trigger
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language plpgsql as $$
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begin
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execute 'create table tab_part_create_1 partition of tab_part_create for values in (1)';
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return null;
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end $$;
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create trigger trig_part_create before insert on tab_part_create
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for each statement execute procedure func_part_create();
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insert into tab_part_create values (1);
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ERROR: cannot CREATE TABLE .. PARTITION OF "tab_part_create" because it is being used by active queries in this session
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CONTEXT: SQL statement "create table tab_part_create_1 partition of tab_part_create for values in (1)"
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PL/pgSQL function func_part_create() line 3 at EXECUTE
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drop table tab_part_create;
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drop function func_part_create();

‎src/test/regress/sql/alter_table.sql

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@@ -2389,6 +2389,22 @@ alter table temp_part_parent attach partition temp_part_child
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drop table perm_part_parent cascade;
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drop table temp_part_parent cascade;
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-- check that attaching partitions to a table while it is being used is
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-- prevented
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create table tab_part_attach (a int) partition by list (a);
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create or replace function func_part_attach() returns trigger
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language plpgsql as $$
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begin
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execute 'create table tab_part_attach_1 (a int)';
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execute 'alter table tab_part_attach attach partition tab_part_attach_1 for values in (1)';
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return null;
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end $$;
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create trigger trig_part_attach before insert on tab_part_attach
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for each statement execute procedure func_part_attach();
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insert into tab_part_attach values (1);
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drop table tab_part_attach;
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drop function func_part_attach();
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-- test case where the partitioning operator is a SQL function whose
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-- evaluation results in the table's relcache being rebuilt partway through
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-- the execution of an ATTACH PARTITION command

‎src/test/regress/sql/create_table.sql

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@@ -679,3 +679,17 @@ create temp table temp_part partition of perm_parted for values in (1, 2); -- er
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create temp table temp_part partition of temp_parted for values in (1, 2); -- ok
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drop table perm_parted cascade;
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drop table temp_parted cascade;
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-- check that adding partitions to a table while it is being used is prevented
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create table tab_part_create (a int) partition by list (a);
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create or replace function func_part_create() returns trigger
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language plpgsql as $$
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begin
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execute 'create table tab_part_create_1 partition of tab_part_create for values in (1)';
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return null;
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end $$;
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create trigger trig_part_create before insert on tab_part_create
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for each statement execute procedure func_part_create();
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insert into tab_part_create values (1);
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drop table tab_part_create;
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drop function func_part_create();

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