src/test/singlenode_regress/sql/reindex_catalog.sql

--
-- Check that system tables can be reindexed.
--
-- Note that this test currently is not included in the default
-- schedules, as currently reindexing catalog tables can cause
-- deadlocks:
--
-- * The lock upgrade between the ShareLock acquired for the reindex
--   and RowExclusiveLock needed for pg_class/pg_index locks can
--   trigger deadlocks.
--
-- * The uniqueness checks performed when reindexing a unique/primary
--   key index possibly need to wait for the transaction of a
--   about-to-deleted row in pg_class to commit. That can cause
--   deadlocks because, in contrast to user tables, locks on catalog
--   tables are routinely released before commit - therefore the lock
--   held for reindexing doesn't guarantee that no running transaction
--   performed modifications in the table underlying the index.
--
--   This is particularly problematic as such conflicts can be
--   triggered even when run in isolation, as a previous session's
--   temporary table cleanup might still be running (even when the
--   session ended from a client perspective).


-- Check reindexing of whole tables
REINDEX TABLE pg_class; -- mapped, non-shared, critical
REINDEX TABLE pg_index; -- non-mapped, non-shared, critical
REINDEX TABLE pg_operator; -- non-mapped, non-shared, critical
REINDEX TABLE pg_database; -- mapped, shared, critical
REINDEX TABLE pg_shdescription; -- mapped, shared non-critical

-- Check that individual system indexes can be reindexed. That's a bit
-- different from the entire-table case because reindex_relation
-- treats e.g. pg_class special.
REINDEX INDEX pg_class_oid_index; -- mapped, non-shared, critical
REINDEX INDEX pg_class_relname_nsp_index; -- mapped, non-shared, non-critical
REINDEX INDEX pg_index_indexrelid_index; -- non-mapped, non-shared, critical
REINDEX INDEX pg_index_indrelid_index; -- non-mapped, non-shared, non-critical
REINDEX INDEX pg_database_oid_index; -- mapped, shared, critical
REINDEX INDEX pg_shdescription_o_c_index; -- mapped, shared, non-critical

-- Check the same REINDEX INDEX statements under parallelism.
BEGIN;
SET min_parallel_table_scan_size = 0;
REINDEX INDEX pg_class_oid_index; -- mapped, non-shared, critical
REINDEX INDEX pg_class_relname_nsp_index; -- mapped, non-shared, non-critical
REINDEX INDEX pg_index_indexrelid_index; -- non-mapped, non-shared, critical
REINDEX INDEX pg_index_indrelid_index; -- non-mapped, non-shared, non-critical
REINDEX INDEX pg_database_oid_index; -- mapped, shared, critical
REINDEX INDEX pg_shdescription_o_c_index; -- mapped, shared, non-critical
ROLLBACK;