From 41faafbd75a5c70fa94bf57e408e6b29c4425ceb Mon Sep 17 00:00:00 2001 From: Michael Paquier Date: Mon, 6 Apr 2020 11:05:54 +0900 Subject: [PATCH] Preserve clustered index after rewrites with ALTER TABLE 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 --- src/backend/commands/tablecmds.c | 46 ++++++++++++++++++++++ src/backend/utils/cache/lsyscache.c | 23 +++++++++++ src/include/utils/lsyscache.h | 1 + src/test/regress/expected/alter_table.out | 48 +++++++++++++++++++++++ src/test/regress/sql/alter_table.sql | 25 ++++++++++++ 5 files changed, 143 insertions(+) diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3a2e2ecc4f..28996f607c 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -176,6 +176,7 @@ typedef struct AlteredTableInfo List *changedIndexOids; /* OIDs of indexes to rebuild */ List *changedIndexDefs; /* string definitions of same */ char *replicaIdentityIndex; /* index to reset as REPLICA IDENTITY */ + char *clusterOnIndex; /* index to use for CLUSTER */ } AlteredTableInfo; /* Struct describing one new constraint to check in Phase 3 scan */ @@ -10331,6 +10332,21 @@ RememberReplicaIdentityForRebuilding(Oid indoid, AlteredTableInfo *tab) tab->replicaIdentityIndex = get_rel_name(indoid); } +/* + * Subroutine for ATExecAlterColumnType: remember any clustered index. + */ +static void +RememberClusterOnForRebuilding(Oid indoid, AlteredTableInfo *tab) +{ + if (!get_index_isclustered(indoid)) + return; + + if (tab->clusterOnIndex) + elog(ERROR, "relation %u has multiple clustered indexes", tab->relid); + + tab->clusterOnIndex = get_rel_name(indoid); +} + /* * Subroutine for ATExecAlterColumnType: remember that a constraint needs * to be rebuilt (which we might already know). @@ -10356,9 +10372,18 @@ RememberConstraintForRebuilding(Oid conoid, AlteredTableInfo *tab) tab->changedConstraintDefs = lappend(tab->changedConstraintDefs, defstring); + /* + * For the index of a constraint, if any, remember if it is used for + * the table's replica identity or if it is a clustered index, so that + * ATPostAlterTypeCleanup() can queue up commands necessary to restore + * those properties. + */ indoid = get_constraint_index(conoid); if (OidIsValid(indoid)) + { RememberReplicaIdentityForRebuilding(indoid, tab); + RememberClusterOnForRebuilding(indoid, tab); + } } } @@ -10402,7 +10427,13 @@ RememberIndexForRebuilding(Oid indoid, AlteredTableInfo *tab) tab->changedIndexDefs = lappend(tab->changedIndexDefs, defstring); + /* + * Remember if this index is used for the table's replica identity + * or if it is a clustered index, so that ATPostAlterTypeCleanup() + * can queue up commands necessary to restore those properties. + */ RememberReplicaIdentityForRebuilding(indoid, tab); + RememberClusterOnForRebuilding(indoid, tab); } } } @@ -10635,6 +10666,21 @@ ATPostAlterTypeCleanup(List **wqueue, AlteredTableInfo *tab, LOCKMODE lockmode) lappend(tab->subcmds[AT_PASS_OLD_CONSTR], cmd); } + /* + * Queue up command to restore marking of index used for cluster. + */ + if (tab->clusterOnIndex) + { + AlterTableCmd *cmd = makeNode(AlterTableCmd); + + cmd->subtype = AT_ClusterOn; + cmd->name = tab->clusterOnIndex; + + /* do it after indexes and constraints */ + tab->subcmds[AT_PASS_OLD_CONSTR] = + lappend(tab->subcmds[AT_PASS_OLD_CONSTR], cmd); + } + /* * It should be okay to use DROP_RESTRICT here, since nothing else should * be depending on these objects. diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c index 047a8ced02..913cad3510 100644 --- a/src/backend/utils/cache/lsyscache.c +++ b/src/backend/utils/cache/lsyscache.c @@ -3181,3 +3181,26 @@ get_index_isreplident(Oid index_oid) return result; } + +/* + * get_index_isclustered + * + * Given the index OID, return pg_index.indisclustered. + */ +bool +get_index_isclustered(Oid index_oid) +{ + bool isclustered; + HeapTuple tuple; + Form_pg_index rd_index; + + tuple = SearchSysCache1(INDEXRELID, ObjectIdGetDatum(index_oid)); + if (!HeapTupleIsValid(tuple)) + elog(ERROR, "cache lookup failed for index %u", index_oid); + + rd_index = (Form_pg_index) GETSTRUCT(tuple); + isclustered = rd_index->indisclustered; + ReleaseSysCache(tuple); + + return isclustered; +} diff --git a/src/include/utils/lsyscache.h b/src/include/utils/lsyscache.h index 3832785c0f..21ec4cbd35 100644 --- a/src/include/utils/lsyscache.h +++ b/src/include/utils/lsyscache.h @@ -179,6 +179,7 @@ extern char *get_namespace_name_or_temp(Oid nspid); extern Oid get_range_subtype(Oid rangeOid); extern Oid get_range_collation(Oid rangeOid); extern bool get_index_isreplident(Oid index_oid); +extern bool get_index_isclustered(Oid index_oid); #define type_is_array(typid) (get_element_type(typid) != InvalidOid) /* type_is_array_domain accepts both plain arrays and domains over arrays */ diff --git a/src/test/regress/expected/alter_table.out b/src/test/regress/expected/alter_table.out index 4e9c15bbd4..a65f706dee 100644 --- a/src/test/regress/expected/alter_table.out +++ b/src/test/regress/expected/alter_table.out @@ -4212,3 +4212,51 @@ 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; diff --git a/src/test/regress/sql/alter_table.sql b/src/test/regress/sql/alter_table.sql index cfc09e859b..9cdb92670e 100644 --- a/src/test/regress/sql/alter_table.sql +++ b/src/test/regress/sql/alter_table.sql @@ -2802,3 +2802,28 @@ 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;