From cea57780afa350da755c66c8ebb0558fb0913f1f Mon Sep 17 00:00:00 2001 From: Masahiko Sawada Date: Mon, 17 Mar 2025 09:20:47 -0700 Subject: [PATCH] Fix assertion failure in parallel vacuum with minimal maintenance_work_mem setting. bbf668d66fbf lowered the minimum value of maintenance_work_mem to 64kB. However, in parallel vacuum cases, since the initial underlying DSA size is 256kB, it attempts to perform a cycle of index vacuuming and table vacuuming with an empty TID store, resulting in an assertion failure. This commit ensures that at least one page is processed before index vacuuming and table vacuuming begins. Backpatched to 17, where the minimum maintenance_work_mem value was lowered. Reviewed-by: Discussion: https://postgr.es/m/CAD21AoCEAmbkkXSKbj4dB+5pJDRL4ZHxrCiLBgES_g_g8mVi1Q@mail.gmail.com Backpatch-through: 17 --- src/backend/access/heap/vacuumlazy.c | 7 +++++-- src/test/regress/expected/vacuum.out | 11 +++++++++++ src/test/regress/sql/vacuum.sql | 12 ++++++++++++ 3 files changed, 28 insertions(+), 2 deletions(-) diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c index 3b91d02605a..e0e0213f046 100644 --- a/src/backend/access/heap/vacuumlazy.c +++ b/src/backend/access/heap/vacuumlazy.c @@ -1263,9 +1263,12 @@ lazy_scan_heap(LVRelState *vacrel) * Consider if we definitely have enough space to process TIDs on page * already. If we are close to overrunning the available space for * dead_items TIDs, pause and do a cycle of vacuuming before we tackle - * this page. + * this page. However, let's force at least one page-worth of tuples + * to be stored as to ensure we do at least some work when the memory + * configured is so low that we run out before storing anything. */ - if (TidStoreMemoryUsage(vacrel->dead_items) > vacrel->dead_items_info->max_bytes) + if (vacrel->dead_items_info->num_items > 0 && + TidStoreMemoryUsage(vacrel->dead_items) > vacrel->dead_items_info->max_bytes) { /* * Before beginning index vacuuming, we release any pin we may diff --git a/src/test/regress/expected/vacuum.out b/src/test/regress/expected/vacuum.out index 1a07dbf67d6..d514be145cc 100644 --- a/src/test/regress/expected/vacuum.out +++ b/src/test/regress/expected/vacuum.out @@ -148,6 +148,10 @@ CREATE INDEX brin_pvactst ON pvactst USING brin (i); CREATE INDEX gin_pvactst ON pvactst USING gin (a); CREATE INDEX gist_pvactst ON pvactst USING gist (p); CREATE INDEX spgist_pvactst ON pvactst USING spgist (p); +CREATE TABLE pvactst2 (i INT) WITH (autovacuum_enabled = off); +INSERT INTO pvactst2 SELECT generate_series(1, 1000); +CREATE INDEX ON pvactst2 (i); +CREATE INDEX ON pvactst2 (i); -- VACUUM invokes parallel index cleanup SET min_parallel_index_scan_size to 0; VACUUM (PARALLEL 2) pvactst; @@ -167,6 +171,12 @@ VACUUM (PARALLEL) pvactst; -- error, cannot use PARALLEL option without parallel ERROR: parallel option requires a value between 0 and 1024 LINE 1: VACUUM (PARALLEL) pvactst; ^ +-- Test parallel vacuum with the minimum maintenance_work_mem with and without +-- dead tuples. +SET maintenance_work_mem TO 64; +VACUUM (PARALLEL 2) pvactst; +UPDATE pvactst SET i = i WHERE i < 1000; +VACUUM (PARALLEL 2) pvactst; -- Test different combinations of parallel and full options for temporary tables CREATE TEMPORARY TABLE tmp (a int PRIMARY KEY); CREATE INDEX tmp_idx1 ON tmp (a); @@ -174,6 +184,7 @@ VACUUM (PARALLEL 1, FULL FALSE) tmp; -- parallel vacuum disabled for temp tables WARNING: disabling parallel option of vacuum on "tmp" --- cannot vacuum temporary tables in parallel VACUUM (PARALLEL 0, FULL TRUE) tmp; -- can specify parallel disabled (even though that's implied by FULL) RESET min_parallel_index_scan_size; +RESET maintenance_work_mem; DROP TABLE pvactst; -- INDEX_CLEANUP option CREATE TABLE no_index_cleanup (i INT PRIMARY KEY, t TEXT); diff --git a/src/test/regress/sql/vacuum.sql b/src/test/regress/sql/vacuum.sql index 5e55079e718..2cc973ff2da 100644 --- a/src/test/regress/sql/vacuum.sql +++ b/src/test/regress/sql/vacuum.sql @@ -113,6 +113,10 @@ CREATE INDEX brin_pvactst ON pvactst USING brin (i); CREATE INDEX gin_pvactst ON pvactst USING gin (a); CREATE INDEX gist_pvactst ON pvactst USING gist (p); CREATE INDEX spgist_pvactst ON pvactst USING spgist (p); +CREATE TABLE pvactst2 (i INT) WITH (autovacuum_enabled = off); +INSERT INTO pvactst2 SELECT generate_series(1, 1000); +CREATE INDEX ON pvactst2 (i); +CREATE INDEX ON pvactst2 (i); -- VACUUM invokes parallel index cleanup SET min_parallel_index_scan_size to 0; @@ -130,12 +134,20 @@ VACUUM (PARALLEL 2, INDEX_CLEANUP FALSE) pvactst; VACUUM (PARALLEL 2, FULL TRUE) pvactst; -- error, cannot use both PARALLEL and FULL VACUUM (PARALLEL) pvactst; -- error, cannot use PARALLEL option without parallel degree +-- Test parallel vacuum with the minimum maintenance_work_mem with and without +-- dead tuples. +SET maintenance_work_mem TO 64; +VACUUM (PARALLEL 2) pvactst; +UPDATE pvactst SET i = i WHERE i < 1000; +VACUUM (PARALLEL 2) pvactst; + -- Test different combinations of parallel and full options for temporary tables CREATE TEMPORARY TABLE tmp (a int PRIMARY KEY); CREATE INDEX tmp_idx1 ON tmp (a); VACUUM (PARALLEL 1, FULL FALSE) tmp; -- parallel vacuum disabled for temp tables VACUUM (PARALLEL 0, FULL TRUE) tmp; -- can specify parallel disabled (even though that's implied by FULL) RESET min_parallel_index_scan_size; +RESET maintenance_work_mem; DROP TABLE pvactst; -- INDEX_CLEANUP option -- 2.43.5