From: Nathan Bossart <nathandbossart@gmail.com>
To: Ian Lawrence Barwick <barwick@gmail.com>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Cc: robertmhaas@gmail.com
Subject: Re: pg_stat_get_backend_subxact() and backend IDs?
Date: Fri, 25 Aug 2023 12:29:49 -0700
Message-ID: <20230825192949.GA1917227@nathanxps13> (raw)
In-Reply-To: <20230825153251.GA1593219@nathanxps13>
References: <CAB8KJ=j-ACb3H4L9a_b3ZG3iCYDW5aEu3WsPAzkm2S7JzS1Few@mail.gmail.com>
<20230824023206.GA1128857@nathanxps13.lan>
<20230824025140.GB1128857@nathanxps13.lan>
<20230824161913.GA1394441@nathanxps13.lan>
<CAB8KJ=iWYvB1odjFRZybsPeUV8HUAiVVjY9RMHSdvWy1t77cLg@mail.gmail.com>
<20230825153251.GA1593219@nathanxps13>
On Fri, Aug 25, 2023 at 08:32:51AM -0700, Nathan Bossart wrote:
> On second thought, renaming these exported functions so close to release is
> probably not a great idea. I should probably skip back-patching that one.
> Or I could have the existing functions call the new ones in v16 for
> backward compatibility...
Here is a new version of the patch that avoids changing the names of the
existing functions. I'm not thrilled about the name
(pgstat_fetch_stat_local_beentry_by_backend_id), so I am open to
suggestions. In any case, I'd like to rename all three of the
pgstat_fetch_stat_* functions in v17.
--
Nathan Bossart
Amazon Web Services: https://aws.amazon.comAttachments:v3-0001-fix-pg_stat_get_backend_subxact-to-use-real-backe.patch (text/x-diff, 3.3K) download
From e1ce8bf67f1b713294ef8d38dbee26bfc7ef16f4 Mon Sep 17 00:00:00 2001
From: Nathan Bossart <nathan@postgresql.org>
Date: Thu, 24 Aug 2023 07:58:01 -0700
Subject: [PATCH v3 1/1] fix pg_stat_get_backend_subxact to use real backend id
---
src/backend/utils/activity/backend_status.c | 39 ++++++++++++++++-----
src/backend/utils/adt/pgstatfuncs.c | 2 +-
src/include/utils/backend_status.h | 1 +
3 files changed, 32 insertions(+), 10 deletions(-)
diff --git a/src/backend/utils/activity/backend_status.c b/src/backend/utils/activity/backend_status.cindex 38f91a495b..231cc5dd9a 100644--- a/src/backend/utils/activity/backend_status.c+++ b/src/backend/utils/activity/backend_status.c@@ -1089,9 +1089,34 @@ cmp_lbestatus(const void *a, const void *b)
PgBackendStatus *
pgstat_fetch_stat_beentry(BackendId beid)
{
- LocalPgBackendStatus key;
LocalPgBackendStatus *ret;
+ ret = pgstat_fetch_stat_local_beentry_by_backend_id(beid);+ if (ret)+ return &ret->backendStatus;++ return NULL;+}+++/* ----------+ * pgstat_fetch_stat_local_beentry_by_backend_id() -+ *+ * Like pgstat_fetch_stat_beentry() but with locally computed additions+ * (like xid and xmin values of the backend)+ *+ * The beid argument is the BackendId of the desired session+ * (note that this is unlike pgstat_fetch_stat_local_beentry()).+ *+ * NB: caller is responsible for checking if the user is permitted to see this+ * info (especially the querystring).+ * ----------+ */+LocalPgBackendStatus *+pgstat_fetch_stat_local_beentry_by_backend_id(BackendId beid)+{+ LocalPgBackendStatus key;+
pgstat_read_current_status();
/*
@@ -1099,14 +1124,10 @@ pgstat_fetch_stat_beentry(BackendId beid)
* bsearch() to search it efficiently.
*/
key.backend_id = beid;
- ret = (LocalPgBackendStatus *) bsearch(&key, localBackendStatusTable,- localNumBackends,- sizeof(LocalPgBackendStatus),- cmp_lbestatus);- if (ret)- return &ret->backendStatus;-- return NULL;+ return (LocalPgBackendStatus *) bsearch(&key, localBackendStatusTable,+ localNumBackends,+ sizeof(LocalPgBackendStatus),+ cmp_lbestatus);
}
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.cindex 2b9742ad21..68ae044399 100644--- a/src/backend/utils/adt/pgstatfuncs.c+++ b/src/backend/utils/adt/pgstatfuncs.c@@ -727,7 +727,7 @@ pg_stat_get_backend_subxact(PG_FUNCTION_ARGS)
BlessTupleDesc(tupdesc);
- if ((local_beentry = pgstat_fetch_stat_local_beentry(beid)) != NULL)+ if ((local_beentry = pgstat_fetch_stat_local_beentry_by_backend_id(beid)) != NULL)
{
/* Fill values and NULLs */
values[0] = Int32GetDatum(local_beentry->backend_subxact_count);
diff --git a/src/include/utils/backend_status.h b/src/include/utils/backend_status.hindex 77939a0aed..060431a39b 100644--- a/src/include/utils/backend_status.h+++ b/src/include/utils/backend_status.h@@ -335,6 +335,7 @@ extern uint64 pgstat_get_my_query_id(void);
extern int pgstat_fetch_stat_numbackends(void);
extern PgBackendStatus *pgstat_fetch_stat_beentry(BackendId beid);
extern LocalPgBackendStatus *pgstat_fetch_stat_local_beentry(int beid);
+extern LocalPgBackendStatus *pgstat_fetch_stat_local_beentry_by_backend_id(BackendId beid);
extern char *pgstat_clip_activity(const char *raw_activity);
--
2.25.1
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To: pgsql-hackers@postgresql.org
Cc: nathandbossart@gmail.com, barwick@gmail.com, robertmhaas@gmail.com
Subject: Re: pg_stat_get_backend_subxact() and backend IDs?
In-Reply-To: <20230825192949.GA1917227@nathanxps13>
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