Fix incorrect WAL description for PREPARE TRANSACTION record.

MasaoFujii · MasaoFujii · commit 0e0174b4973a · 2025-05-21T11:56:39.000+09:00
Since commit 8b1dccd, the PREPARE TRANSACTION WAL record includes information about dropped statistics entries. However, the WAL resource manager description function for PREPARE TRANSACTION record failed to parse this information correctly and always assumed there were no such entries. As a result, for example, pg_waldump could not display the dropped statistics entries stored in PREPARE TRANSACTION records. The root cause was that ParsePrepareRecord() did not set the number of statistics entries to drop on commit or abort. These values remained zero-initialized and were never updated from the parsed record. This commit fixes the issue by properly setting those values during parsing. With this fix, pg_waldump can now correctly report dropped statistics entries in PREPARE TRANSACTION records. Back-patch to v15, where commit 8b1dccd was introduced. Author: Daniil Davydov <3danissimo@gmail.com> Reviewed-by: Fujii Masao <masao.fujii@gmail.com> Discussion: https://postgr.es/m/CAJDiXgh-6Epb2XiJe4uL0zF-cf0_s_7Lw1TfEHDMLzYjEmfGOw@mail.gmail.com Backpatch-through: 15
diff --git a/src/backend/access/rmgrdesc/xactdesc.c b/src/backend/access/rmgrdesc/xactdesc.c
@@ -252,6 +252,8 @@ ParsePrepareRecord(uint8 info, xl_xact_prepare *xlrec, xl_xact_parsed_prepare *p
 	parsed->nsubxacts = xlrec->nsubxacts;
 	parsed->nrels = xlrec->ncommitrels;
 	parsed->nabortrels = xlrec->nabortrels;
+	parsed->nstats = xlrec->ncommitstats;
+	parsed->nabortstats = xlrec->nabortstats;
 	parsed->nmsgs = xlrec->ninvalmsgs;
 
 	strncpy(parsed->twophase_gid, bufptr, xlrec->gidlen);
