improve DEBUG1 logging of parallel workers for CREATE INDEX?

Started by Sami Imseihabout 1 year ago19 messages

samimseih@gmail.com

about 1 year ago

1 attachment(s)

While reviewing patch [1]/messages/by-id/CAA5RZ0tS=Fmgku9=qCp-U4EBC-dqVtj+v_EGrKV_NA=THnUDsQ@mail.gmail.com, I realized that the DEBUG1 message
for CREATE INDEX could do better in providing information
about parallel workers launched. Currently, the message just
shows how many workers are planned, but a user may want
to ensure that they have the appropriate number of workers
launched as well when they enable DEBUG1 logging.

Therefore, I want to suggest that instead of:

postgres=# CREATE INDEX tbl_c1 ON tbl(c1);
DEBUG: building index "tbl_c1" on table "tbl" with request for 2
parallel workers
DEBUG: index "tbl_c1" can safely use deduplication
CREATE INDEX

to enhance the message to:

postgres=# create index tbl_c1 on tbl(c1);
DEBUG: building index "tbl_c1" on table "tbl"
DEBUG: launched 0 parallel vacuum workers for index vacuuming (planned: 2)
DEBUG: index "tbl_c1" can safely use deduplication
CREATE INDEX
postgres=#

I prepared a simple patch, attached, for this. The log message matches
the format
used in VACUUM VERBOSE ( for consistency sake ).

Also, I think the documentation in [2]https://www.postgresql.org/docs/current/sql-createindex.html should be updated to mention that DEBUG1
can be used to view parallel worker usage for the build, but I have
not included it in
the patch yet.

Any thoughts?

[1]: /messages/by-id/CAA5RZ0tS=Fmgku9=qCp-U4EBC-dqVtj+v_EGrKV_NA=THnUDsQ@mail.gmail.com

[2]: https://www.postgresql.org/docs/current/sql-createindex.html

Regards,

Sami Imseih
Amazon Web Services (AWS)

Attachments:

0001-improve-DEBUG1-logging-of-parallel-workers-for-CREAT.patchapplication/octet-stream; name=0001-improve-DEBUG1-logging-of-parallel-workers-for-CREAT.patchDownload

From 1cbe4d0aa375df0371da19ca88d2e0dda2708ea2 Mon Sep 17 00:00:00 2001
From: Sami Imseih <simseih@amazon.com>
Date: Fri, 3 Jan 2025 12:16:37 -0600
Subject: [PATCH 1/1] improve DEBUG1 logging of parallel workers for CREATE
 INDEX

---
 src/backend/access/brin/brin.c      | 4 ++++
 src/backend/access/nbtree/nbtsort.c | 4 ++++
 src/backend/catalog/index.c         | 5 ++---
 3 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/src/backend/access/brin/brin.c b/src/backend/access/brin/brin.c
index 9a98454757..f587e13135 100644
--- a/src/backend/access/brin/brin.c
+++ b/src/backend/access/brin/brin.c
@@ -2512,6 +2512,10 @@ _brin_begin_parallel(BrinBuildState *buildstate, Relation heap, Relation index,
 	brinleader->walusage = walusage;
 	brinleader->bufferusage = bufferusage;
 
+	ereport(DEBUG1,
+			(errmsg_internal("launched %d parallel vacuum workers for index vacuuming (planned: %d)",
+							 pcxt->nworkers_launched, pcxt->nworkers_to_launch)));
+
 	/* If no workers were successfully launched, back out (do serial build) */
 	if (pcxt->nworkers_launched == 0)
 	{
diff --git a/src/backend/access/nbtree/nbtsort.c b/src/backend/access/nbtree/nbtsort.c
index 7aba852db9..b9f39aea73 100644
--- a/src/backend/access/nbtree/nbtsort.c
+++ b/src/backend/access/nbtree/nbtsort.c
@@ -1582,6 +1582,10 @@ _bt_begin_parallel(BTBuildState *buildstate, bool isconcurrent, int request)
 	btleader->walusage = walusage;
 	btleader->bufferusage = bufferusage;
 
+	ereport(DEBUG1,
+			(errmsg_internal("launched %d parallel vacuum workers for index vacuuming (planned: %d)",
+							 pcxt->nworkers_launched, pcxt->nworkers_to_launch)));
+
 	/* If no workers were successfully launched, back out (do serial build) */
 	if (pcxt->nworkers_launched == 0)
 	{
diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index 221fbb4e28..e7846fd9d4 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -3007,10 +3007,9 @@ index_build(Relation heapRelation,
 								 RelationGetRelationName(heapRelation))));
 	else
 		ereport(DEBUG1,
-				(errmsg_internal("building index \"%s\" on table \"%s\" with request for %d parallel workers",
+				(errmsg_internal("building index \"%s\" on table \"%s\"",
 								 RelationGetRelationName(indexRelation),
-								 RelationGetRelationName(heapRelation),
-								 indexInfo->ii_ParallelWorkers)));
+								 RelationGetRelationName(heapRelation))));
 
 	/*
 	 * Switch to the table owner's userid, so that any index functions are run
-- 
2.39.5 (Apple Git-154)