Thread: BUG #17211: Partitioned index partition does not inherit table partition tablespace
BUG #17211: Partitioned index partition does not inherit table partition tablespace
From
PG Bug reporting form
Date:
The following bug has been logged on the website: Bug reference: 17211 Logged by: Andy S Email address: gatekeeper.mail@gmail.com PostgreSQL version: 14.0 Operating system: Debian Bullseye Description: Suppose we have 2 tablespaces: pg_default (which is slow) fast We also have a partitioned table: create table a (id serial not null, b int not null primary key, c int not null, d int) partition by hash (b); and 2 partitions: create table a_1 partition of a for values with (modulus 2, remainder 0); create table a_2 partition of a for values with (modulus 2, remainder 1) tablespace fast; This successfully allocates table a_2 pages within the 'fast' tablespace; but this fails to allocate a_2_pkey primary key index there too and the result is the index is allocated on tablespace oid(0) which means pg_default I guess, at least the corresponding relfilenode is allocated within the pg_default tablespace. There's also a CREATE TABLE hack for index/constraint declaration within the command that allows USING INDEX TABLESPACE, though there's an unresolved error loop in partitioned tables use-case for such a syntax: create table a_2 partition of a (primary key using index tablespace fast) for values with (modulus 2, remainder 1) tablespace fast; fails since there's no primary key definition provided create table a_2 partition of a (primary key (b) using index tablespace fast) for values with (modulus 2, remainder 1) tablespace fast; fails with 'ERROR: multiple primary keys for table "a_2" are not allowed' The only possibility for a user to then allocate both index(es) and a table on a non-default tablespace is to create a partition, scan pg_class/pg_index to find all the names of indexes' partitions allocated for the new table, traverse them programmatically and ALTER INDEX SET TABLESPACE them. Which does not seem convenient since there's a simpler syntax/approach for a regular table.
Re: BUG #17211: Partitioned index partition does not inherit table partition tablespace
From
"Euler Taveira"
Date:
On Fri, Oct 1, 2021, at 3:07 PM, PG Bug reporting form wrote:
Suppose we have 2 tablespaces:pg_default (which is slow)fastWe also have a partitioned table:create table a (id serial not null, b int not null primary key, c int notnull, d int) partition by hash (b);and 2 partitions:create table a_1 partition of a for values with (modulus 2, remainder 0);create table a_2 partition of a for values with (modulus 2, remainder 1)tablespace fast;This successfully allocates table a_2 pages within the 'fast' tablespace;but this fails to allocate a_2_pkey primary key index there too and theresult is the index is allocated on tablespace oid(0) which means pg_defaultI guess, at least the corresponding relfilenode is allocated within thepg_default tablespace.
That's how it was designed. TABLESPACE clause at the end of CREATE TABLE set
the tablespace only for the table. The index is stored based on the
default_tablespace [1] value.
Since there is no way to specify USING INDEX TABLESPACE for partitions, you
should set default_tablespace to achieve what you want.
CREATE TABLE a (
id serial NOT NULL,
b int NOT NULL PRIMARY KEY,
c int NOT NULL,
d int
) PARTITION BY hash (b);
CREATE TABLE a_1 PARTITION OF a
FOR VALUES WITH (MODULUS 3, REMAINDER 0);
SET default_tablespace TO 'fast';
-- the TABLESPACE clause is not required
-- table -> fast ; index -> fast
CREATE TABLE a_2 PARTITION OF a
FOR VALUES WITH (MODULUS 3, REMAINDER 1) TABLESPACE fast;
-- table -> tablespace slow ; index -> tablespace fast
CREATE TABLE a_3 PARTITION OF a
FOR VALUES WITH (MODULUS 3, REMAINDER 2) TABLESPACE slow;
RESET default_tablespace;