Hi!
Currently in pg_stat_statements save/load routines the whole pgssEntry
entity data are written/read with its last field
slock_t mutex;
which is actually not used then.
This small patch fixes this issue. Hope, it will be useful.
Respectfully,
Mikhail Litsarev,
Postgres Professional: https://postgrespro.com
From 40392a495a91dfc1ee2c62812949eebe54276625 Mon Sep 17 00:00:00 2001
From: Mikhail Litsarev <m.litsa...@postgrespro.ru>
Date: Mon, 20 Jan 2025 15:40:12 +0300
Subject: [PATCH] pg_stat_statements: improve loading and saving routines for
the dump file.
Exclude reading/writing pgssEntry mutex from/into the dump file.
Update the magic number identifying the stats file format.
---
contrib/pg_stat_statements/pg_stat_statements.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index bebf8134eb0..0511a2b7ca1 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -82,7 +82,7 @@ PG_MODULE_MAGIC;
#define PGSS_TEXT_FILE PG_STAT_TMP_DIR "/pgss_query_texts.stat"
/* Magic number identifying the stats file format */
-static const uint32 PGSS_FILE_HEADER = 0x20220408;
+static const uint32 PGSS_FILE_HEADER = 0x20250120;
/* PostgreSQL major version number, changes in which invalidate all entries */
static const uint32 PGSS_PG_MAJOR_VERSION = PG_VERSION_NUM / 100;
@@ -233,7 +233,8 @@ typedef struct pgssEntry
int encoding; /* query text encoding */
TimestampTz stats_since; /* timestamp of entry allocation */
TimestampTz minmax_stats_since; /* timestamp of last min/max values reset */
- slock_t mutex; /* protects the counters only */
+ /* protects the counters only. Should be the very last field */
+ slock_t mutex;
} pgssEntry;
/*
@@ -625,7 +626,8 @@ pgss_shmem_startup(void)
pgssEntry *entry;
Size query_offset;
- if (fread(&temp, sizeof(pgssEntry), 1, file) != 1)
+ /* Read whole pgssEntry excluding very last mutex field */
+ if (fread(&temp, offsetof(pgssEntry, mutex), 1, file) != 1)
goto read_error;
/* Encoding is the only field we can easily sanity-check */
@@ -782,7 +784,8 @@ pgss_shmem_shutdown(int code, Datum arg)
if (qstr == NULL)
continue; /* Ignore any entries with bogus texts */
- if (fwrite(entry, sizeof(pgssEntry), 1, file) != 1 ||
+ /* Write whole pgssEntry excluding very last mutex field */
+ if (fwrite(entry, offsetof(pgssEntry, mutex), 1, file) != 1 ||
fwrite(qstr, 1, len + 1, file) != len + 1)
{
/* note: we assume hash_seq_term won't change errno */
--
2.34.1
