From: Peter Geoghegan Date: Tue, 24 Jan 2023 23:15:33 +0000 (-0800) Subject: Update more obsolete multixact.c comments. X-Git-Url: http://git.postgresql.org/gitweb/?a=commitdiff_plain;h=8f8f11593258d04e9a58365865f7daf123e24bb1;p=users%2Fgsingh%2Fpostgres.git Update more obsolete multixact.c comments. Update some remaining comments in multixact.c that still described SLRU truncation as happening in the checkpointer, rather than during VACUUM. Follow-up to commit 5212d447. Shi yu, with tweaks by me. Author: Shi yu Discussion: https://postgr.es/m/OSZPR01MB631066BF246F8F74E83222FCFDC69@OSZPR01MB6310.jpnprd01.prod.outlook.com --- diff --git a/src/backend/access/transam/multixact.c b/src/backend/access/transam/multixact.c index e75e1fdf74..fe6698d5ff 100644 --- a/src/backend/access/transam/multixact.c +++ b/src/backend/access/transam/multixact.c @@ -261,7 +261,7 @@ typedef struct MultiXactStateData * we compute it (using nextMXact if none are valid). Each backend is * required not to attempt to access any SLRU data for MultiXactIds older * than its own OldestVisibleMXactId[] setting; this is necessary because - * the checkpointer could truncate away such data at any instant. + * the relevant SLRU data can be concurrently truncated away. * * The oldest valid value among all of the OldestMemberMXactId[] and * OldestVisibleMXactId[] entries is considered by vacuum as the earliest @@ -669,8 +669,8 @@ MultiXactIdSetOldestMember(void) * * We set the OldestVisibleMXactId for a given transaction the first time * it's going to inspect any MultiXactId. Once we have set this, we are - * guaranteed that the checkpointer won't truncate off SLRU data for - * MultiXactIds at or after our OldestVisibleMXactId. + * guaranteed that SLRU data for MultiXactIds >= our own OldestVisibleMXactId + * won't be truncated away. * * The value to set is the oldest of nextMXact and all the valid per-backend * OldestMemberMXactId[] entries. Because of the locking we do, we can be