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From: Alvaro Herrera <[email protected]>
To: Fujii Masao <[email protected]>
Cc: [email protected]
Cc: pgsql-docs <[email protected]>
Cc: PostgreSQL-development <[email protected]>
Subject: Re: max_worker_processes on the standby
Date: Fri, 2 Oct 2015 11:58:39 -0300
Message-ID: <[email protected]> (raw)
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Fujii Masao wrote:

> What happens if pg_xact_commit_timestamp() is called in standby after
> track_commit_timestamp is disabled in master, DeactivateCommitTs() is
> called and all commit_ts files are removed in standby? I tried that case
> and got the following assertion failure.

Ah.  So the standby needs to keep the module activated if it's enabled
locally, even when it receives a message that the master turned it off.
Here's a patch.

Thanks for your continued testing!

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Álvaro Herrera                http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services


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Attachments:

  [text/x-diff] committs.patch (1.0K, 2-committs.patch)
  download | inline diff:
commit 7441f88b746b7522f1714ed9fec95c3c4fe1dacb
Author:     Alvaro Herrera <[email protected]>
AuthorDate: Fri Oct 2 11:39:44 2015 -0300
CommitDate: Fri Oct 2 11:39:44 2015 -0300

    Don't disable commit_ts in standby if enabled locally
    
    Bug noticed by Fujii Masao

diff --git a/src/backend/access/transam/commit_ts.c b/src/backend/access/transam/commit_ts.c
index 79ca04a..24b8291 100644
--- a/src/backend/access/transam/commit_ts.c
+++ b/src/backend/access/transam/commit_ts.c
@@ -583,14 +583,15 @@ CommitTsParameterChange(bool newvalue, bool oldvalue)
 	 * pg_control.  If the old value was already set, we already did this, so
 	 * don't do anything.
 	 *
-	 * If the module is disabled in the master, disable it here too.
+	 * If the module is disabled in the master, disable it here too, unless
+	 * the module is enabled locally.
 	 */
 	if (newvalue)
 	{
 		if (!track_commit_timestamp && !oldvalue)
 			ActivateCommitTs();
 	}
-	else if (oldvalue)
+	else if (!track_commit_timestamp && oldvalue)
 		DeactivateCommitTs(false);
 }
 


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