Re: tracking commit timestamps

On Wed, Dec 3, 2014 at 11:54 PM, Alvaro Herrera
<alvherre(at)2ndquadrant(dot)com> wrote:
> Pushed with some extra cosmetic tweaks.

I got the following assertion failure when I executed pg_xact_commit_timestamp()
in the standby server.

=# select pg_xact_commit_timestamp('1000'::xid);
TRAP: FailedAssertion("!(((oldestCommitTs) != ((TransactionId) 0)) ==
((newestCommitTs) != ((TransactionId) 0)))", File: "commit_ts.c",
Line: 315)
server closed the connection unexpectedly
This probably means the server terminated abnormally
before or while processing the request.
The connection to the server was lost. Attempting reset: 2014-12-04
12:01:08 JST sby1 LOG: server process (PID 15545) was terminated by
signal 6: Aborted
2014-12-04 12:01:08 JST sby1 DETAIL: Failed process was running:
select pg_xact_commit_timestamp('1000'::xid);

The way to reproduce this problem is

#1. set up and start the master and standby servers with
track_commit_timestamp disabled
#2. enable track_commit_timestamp in the master and restart the master
#3. run some write transactions
#4. enable track_commit_timestamp in the standby and restart the standby
#5. execute "select pg_xact_commit_timestamp('1000'::xid)" in the standby

BTW, at the step #4, I got the following log messages. This might be a hint for
this problem.

LOG: file "pg_commit_ts/0000" doesn't exist, reading as zeroes
CONTEXT: xlog redo Transaction/COMMIT: 2014-12-04 12:00:16.428702+09;
inval msgs: catcache 59 catcache 58 catcache 59 catcache 58 catcache
45 catcache 44 catcache 7 catcache 6 catcache 7 catcache 6 catcache 7
catcache 6 catcache 7 catcache 6 catcache 7 catcache 6 catcache 7
catcache 6 catcache 7 catcache 6 catcache 7 catcache 6 snapshot 2608
relcache 16384

Regards,

--
Fujii Masao