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Preserve clustered index after rewrites with ALTER TABLE

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A table rewritten by ALTER TABLE would lose tracking of an index usable
for CLUSTER.  This setting is tracked by pg_index.indisclustered and is
controlled by ALTER TABLE, so some extra work was needed to restore it
properly.  Note that ALTER TABLE only marks the index that can be used
for clustering, and does not do the actual operation.

Author: Amit Langote, Justin Pryzby
Reviewed-by: Ibrar Ahmed, Michael Paquier
Discussion: https://postgr.es/m/20200202161718.GI13621@telsasoft.com
Backpatch-through: 9.5
This commit is contained in:
Michael Paquier
2020-04-06 11:05:47 +09:00
parent 23a0cf2c9f
commit 3e62dd3a93
5 changed files with 143 additions and 0 deletions
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48
src/test/regress/expected/alter_table.out
View File

@ -4186,3 +4186,51 @@ create trigger xtrig
update bar1 set a = a + 1;
INFO: a=1, b=1
/* End test case for bug #16242 */
-- Test that ALTER TABLE rewrite preserves a clustered index
-- for normal indexes and indexes on constraints.
create table alttype_cluster (a int);
alter table alttype_cluster add primary key (a);
create index alttype_cluster_ind on alttype_cluster (a);
alter table alttype_cluster cluster on alttype_cluster_ind;
-- Normal index remains clustered.
select indexrelid::regclass, indisclustered from pg_index
where indrelid = 'alttype_cluster'::regclass
order by indexrelid::regclass::text;
indexrelid | indisclustered
----------------------+----------------
alttype_cluster_ind | t
alttype_cluster_pkey | f
(2 rows)
alter table alttype_cluster alter a type bigint;
select indexrelid::regclass, indisclustered from pg_index
where indrelid = 'alttype_cluster'::regclass
order by indexrelid::regclass::text;
indexrelid | indisclustered
----------------------+----------------
alttype_cluster_ind | t
alttype_cluster_pkey | f
(2 rows)
-- Constraint index remains clustered.
alter table alttype_cluster cluster on alttype_cluster_pkey;
select indexrelid::regclass, indisclustered from pg_index
where indrelid = 'alttype_cluster'::regclass
order by indexrelid::regclass::text;
indexrelid | indisclustered
----------------------+----------------
alttype_cluster_ind | f
alttype_cluster_pkey | t
(2 rows)
alter table alttype_cluster alter a type int;
select indexrelid::regclass, indisclustered from pg_index
where indrelid = 'alttype_cluster'::regclass
order by indexrelid::regclass::text;
indexrelid | indisclustered
----------------------+----------------
alttype_cluster_ind | f
alttype_cluster_pkey | t
(2 rows)
drop table alttype_cluster;

25
src/test/regress/sql/alter_table.sql
View File

@ -2814,3 +2814,28 @@ create trigger xtrig
update bar1 set a = a + 1;
/* End test case for bug #16242 */
-- Test that ALTER TABLE rewrite preserves a clustered index
-- for normal indexes and indexes on constraints.
create table alttype_cluster (a int);
alter table alttype_cluster add primary key (a);
create index alttype_cluster_ind on alttype_cluster (a);
alter table alttype_cluster cluster on alttype_cluster_ind;
-- Normal index remains clustered.
select indexrelid::regclass, indisclustered from pg_index
where indrelid = 'alttype_cluster'::regclass
order by indexrelid::regclass::text;
alter table alttype_cluster alter a type bigint;
select indexrelid::regclass, indisclustered from pg_index
where indrelid = 'alttype_cluster'::regclass
order by indexrelid::regclass::text;
-- Constraint index remains clustered.
alter table alttype_cluster cluster on alttype_cluster_pkey;
select indexrelid::regclass, indisclustered from pg_index
where indrelid = 'alttype_cluster'::regclass
order by indexrelid::regclass::text;
alter table alttype_cluster alter a type int;
select indexrelid::regclass, indisclustered from pg_index
where indrelid = 'alttype_cluster'::regclass
order by indexrelid::regclass::text;
drop table alttype_cluster;