This patch does not have a reviewer, so I've decided to try myself on. Disclaimer: although I review quite a lot of code daily, this is my first review for PostgreSQL. I don't know code very well, and frankly I don't really know C very well. Hope my effort are not vain and will be helpful to somebody. I'll be happy for review on review and any tips on process.
Summary ======= I favour this patch. Current behaviour is indeed confusing. If we keep current behaviour we need to update docs and maybe also print a warning when using -f with a file name. Thank you for submission, but i'm afraid there is a bit more work here: - There is a bug, making it hard to test. Please fix. - Please add some tests. Submission review ============== Patch applies cleanly on HEAD. Tests succeed. There are no new or affected by this patch tests. Given that I've found a trivial bug (see below), a test should be created. Usability review ============ I believe I've immediately hit a corner case: 1) I've created a new instance, started it and run `./bin/pg_xlogdump -f db/pg_wal/000000010000000000000001`. This spewed quite a lot of stuff, as expected. 2) I've connected to the same instance and ran following: # SELECT pg_switch_xlog(); pg_switch_xlog ---------------- 0/14FA3D8 (1 row) xlogdump immediately crashed with following: pg_xlogdump: FATAL: could not find file "000000010000000000000002": No such file or directory Problem is that Postgres does not create file until it's actually needed. So 000000010000000000000002 indeed was not there until after I've run some transactions. I believe same would happen after pg_start_backup(), etc. Feature review =========== See above. Can't do more testing. Performance review =============== n/a Coding review =========== LGTM Architecture review ============== n/a -- Vladimir Rusinov Bigtable SRE Google Ireland Ltd.,Gordon House, Barrow Street, Dublin 4, Ireland Registered in Dublin, Ireland Registration Number: 368047 On Mon, Oct 3, 2016 at 5:44 AM, Michael Paquier <michael.paqu...@gmail.com> wrote: > On Mon, Jul 18, 2016 at 8:10 PM, Magnus Hagander <mag...@hagander.net> > wrote: > > > > > > On Thu, Jul 14, 2016 at 8:27 PM, Andres Freund <and...@anarazel.de> > wrote: > >> > >> On 2016-07-14 13:46:23 +0200, Magnus Hagander wrote: > >> > Currently, if you run pg_xlogdump with -f, you have to specify an end > >> > position in an existing file, or if you don't it will only follow > until > >> > the > >> > end of the current file. > >> > >> That's because specifying a file explicitly says that you only want to > >> look at that file, specifying two files that you want the range > >> inclusively between the two files. -f works if you just use -s. > > > > > > Hmm. It does now. I'm *sure* it didn't when I was testing it. It must've > > been something else that was broken at that point :) > > Same as Andres here, my understanding is that one file means that you > just want to look at this file, and two files permits to look at a > range of changes. But I have no argument against changing the current > behavior either. > > >> > I'd appreciate a review of that by someone who's done more work on the > >> > xlog > >> > stuff, but it seems trivial to me. Not sure I can argue it's a bugfix > >> > though, since the usecase simply did not work... > >> > >> I'd say it's working as intended, and you want to change that > >> intent. That's fair, but I'd not call it a bug, and I'd say it's not > >> really 9.6 material. > > > > Based on that, I agree that it's working as intended. > > > > And definitely that it's not 9.6 material. > > > > I'll stick it on the CF page so I don't forget about it. > > Moved to next CF. Magnus, you may want to finish wrapping that if you > still intend to change the current behavior. > -- > Michael > > > -- > Sent via pgsql-hackers mailing list (email@example.com) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-hackers >
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