[HACKERS] HS and clog

2013-03-30 Thread Andres Freund
Hi, During the investigation of http://archives.postgresql.org/message-id/CAL_0b1t%3DWuM6roO8dki%3Dw8DhH8P8whhohbPjReymmQUrOcNT2A%40mail.gmail.com I noticed that during HS we do the following in RecordKnownAssignedTransactionIds: if (TransactionIdFollows(xid, latestObservedXid))

Re: [HACKERS] HS and clog

2013-03-30 Thread Simon Riggs
On 30 March 2013 18:20, Andres Freund and...@2ndquadrant.com wrote: Simon, do you remember why you added that? That doesn't look like code I added, but I'll look some more. -- Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training Services

Re: [HACKERS] HS and clog

2013-03-30 Thread Simon Riggs
On 30 March 2013 18:20, Andres Freund and...@2ndquadrant.com wrote: Imo this shouldn't be needed. In principle, I think your premise looks correct. ExtendCLOG() is not needed. If the xid truly is known assigned at a point in time, then the clog should already have been extended to allow that.

Re: [HACKERS] HS and clog

2013-03-30 Thread Tom Lane
Simon Riggs si...@2ndquadrant.com writes: On 30 March 2013 18:20, Andres Freund and...@2ndquadrant.com wrote: Imo this shouldn't be needed. In principle, I think your premise looks correct. ExtendCLOG() is not needed. If the xid truly is known assigned at a point in time, then the clog

Re: [HACKERS] HS and clog

2013-03-30 Thread Andres Freund
On 2013-03-30 18:24:44 -0400, Tom Lane wrote: Simon Riggs si...@2ndquadrant.com writes: On 30 March 2013 18:20, Andres Freund and...@2ndquadrant.com wrote: Imo this shouldn't be needed. In principle, I think your premise looks correct. ExtendCLOG() is not needed. If the xid truly

Re: [HACKERS] HS and clog

2013-03-30 Thread Andres Freund
On 2013-03-30 23:58:26 +0100, Andres Freund wrote: I am pretty sure that the scenario you describe happens for SUBTRANS tho. Leading to the reported bug. For a slightly too long explanation see: http://archives.postgresql.org/message-id/20130330172144.GI28736%40alap2.anarazel.de Greetings,