From: Fujii Masao <masao.fujii@oss.nttdata.com>
To: zoulx1982@163.com
To: pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #16931: source code problem about commit_ts
Date: Thu, 18 Mar 2021 19:19:10 +0900
Message-ID: <d5b98b4b-a3e3-8095-cfb9-aafb5dbe4f7b@oss.nttdata.com> (raw)
In-Reply-To: <16931-620d0f2fdc6108f1@postgresql.org>
References: <16931-620d0f2fdc6108f1@postgresql.org>
On 2021/03/18 13:36, PG Bug reporting form wrote:
> The following bug has been logged on the website:
>
> Bug reference: 16931
> Logged by: lx zou
> Email address: zoulx1982@163.com
> PostgreSQL version: 13.2
> Operating system: Linux
> Description:
>
> Hi,
> recently i am reading commit ts code, and i have a problem about it.
> i found commit_ts_redo call TransactionTreeSetCommitTsData with last param
> `write_xlog` true,
> but RecordTransactionCommitPrepared and RecordTransactionCommit call
> TransactionTreeSetCommitTsData
> with `write_xlog` false, which cause there are never xlog with commit_ts -
> COMMIT_TS_SETTS type.
> thanks for your time.
I guess that TransactionTreeSetCommitTsData(write_xlog=true) is basically
used by some extensions using commit_ts.
IIUC commit_ts_redo() is called during recovery. So it's strange that
commit_ts_redo() calls TransactionTreeSetCommitTsData() with write_xlog=true
because no new WAL can be generated during recovery. Probably this is a bug,
and it should be called with write_xlog=false, instead. Patch attached.
Also one problem is that there is no test for WAL replay of COMMIT_TS_SETTS
for now. Maybe this is why we could not find that bug.
Regards,
--
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION
diff --git a/src/backend/access/transam/commit_ts.c b/src/backend/access/transam/commit_ts.cindex 48e8d66286..268bdba339 100644--- a/src/backend/access/transam/commit_ts.c+++ b/src/backend/access/transam/commit_ts.c@@ -1074,7 +1074,7 @@ commit_ts_redo(XLogReaderState *record)
subxids = NULL;
TransactionTreeSetCommitTsData(setts->mainxid, nsubxids, subxids,
- setts->timestamp, setts->nodeid, true);+ setts->timestamp, setts->nodeid, false);
if (subxids)
pfree(subxids);
}
Attachments:
[text/plain] bugfix.patch (519B, ../d5b98b4b-a3e3-8095-cfb9-aafb5dbe4f7b@oss.nttdata.com/2-bugfix.patch)
download | inline diff:diff --git a/src/backend/access/transam/commit_ts.c b/src/backend/access/transam/commit_ts.cindex 48e8d66286..268bdba339 100644--- a/src/backend/access/transam/commit_ts.c+++ b/src/backend/access/transam/commit_ts.c@@ -1074,7 +1074,7 @@ commit_ts_redo(XLogReaderState *record)
subxids = NULL;
TransactionTreeSetCommitTsData(setts->mainxid, nsubxids, subxids,
- setts->timestamp, setts->nodeid, true);+ setts->timestamp, setts->nodeid, false);
if (subxids)
pfree(subxids);
}
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To: pgsql-bugs@postgresql.org
Cc: masao.fujii@oss.nttdata.com, zoulx1982@163.com, pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #16931: source code problem about commit_ts
In-Reply-To: <d5b98b4b-a3e3-8095-cfb9-aafb5dbe4f7b@oss.nttdata.com>
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