From 8492feb98f6df3f0f03e84ed56f0d1cbb2ac514c Mon Sep 17 00:00:00 2001 From: Tomas Vondra Date: Mon, 3 Mar 2025 16:53:03 +0100 Subject: Allow parallel CREATE INDEX for GIN indexes Allow using parallel workers to build a GIN index, similarly to BTREE and BRIN. For large tables this may result in significant speedup when the build is CPU-bound. The work is divided so that each worker builds index entries on a subset of the table, determined by the regular parallel scan used to read the data. Each worker uses a local tuplesort to sort and merge the entries for the same key. The TID lists do not overlap (for a given key), which means the merge sort simply concatenates the two lists. The merged entries are written into a shared tuplesort for the leader. The leader needs to merge the sorted entries again, before writing them into the index. But this way a significant part of the work happens in the workers, and the leader is left with merging fewer large entries, which is more efficient. Most of the parallelism infrastructure is a simplified copy of the code used by BTREE indexes, omitting the parts irrelevant for GIN indexes (e.g. uniqueness checks). Original patch by me, with reviews and substantial improvements by Matthias van de Meent, certainly enough to make him a co-author. Author: Tomas Vondra, Matthias van de Meent Reviewed-by: Matthias van de Meent, Andy Fan, Kirill Reshke Discussion: https://postgr.es/m/6ab4003f-a8b8-4d75-a67f-f25ad98582dc%40enterprisedb.com --- src/backend/access/transam/parallel.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'src/backend/access/transam/parallel.c') diff --git a/src/backend/access/transam/parallel.c b/src/backend/access/transam/parallel.c index 4ab5df92133..f6d81d6e1fc 100644 --- a/src/backend/access/transam/parallel.c +++ b/src/backend/access/transam/parallel.c @@ -15,6 +15,7 @@ #include "postgres.h" #include "access/brin.h" +#include "access/gin.h" #include "access/nbtree.h" #include "access/parallel.h" #include "access/session.h" @@ -148,6 +149,9 @@ static const struct { "_brin_parallel_build_main", _brin_parallel_build_main }, + { + "_gin_parallel_build_main", _gin_parallel_build_main + }, { "parallel_vacuum_main", parallel_vacuum_main } -- cgit v1.2.3