On Wed, Jun 1, 2011 at 7:28 PM, Robert Haas <robertmh...@gmail.com> wrote: > On Thu, May 26, 2011 at 12:34 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: >> Alvaro Herrera <alvhe...@commandprompt.com> writes: >>> Excerpts from Euler Taveira de Oliveira's message of jue may 26 12:00:05 >>> -0400 2011: >>>> I think we should emit the real cause in those cases, if possible (not too >>>> much overhead). The message would be "Unlogged table content is not >>>> available >>>> in standby server". >> >>> I guess what it should do is create an empty file in the slave. >> >> Probably it should, because won't the table malfunction after the slave >> is promoted to master, if there's no file at all there? Or will the >> process of coming live create an empty file even if there was none? > > Coming live creates an empty file. > >> But Euler is pointing out a different issue, which is usability. If the >> slave just acts like the table is present but empty, we are likely to >> get bug reports about that too. An error telling you you aren't allowed >> to access such a table on slaves would be more user-friendly, if we can >> do it without too much pain. > > I looked into this a bit. A few observations: > > (1) This problem is actually not confined to unlogged tables; > temporary tables have the same issue. For example, if you create a > temporary table on the master and then, on the slave, do SELECT * FROM > pg_temp_3.hi_mom (or whatever the name of the temp schema where the > temp table is) you get the same error. In fact I suspect if you took > a base backup that included the temporary relation and matched the > backend ID you could even manage to read out the old contents (modulo > any fun and exciting XID wraparound issues). But the problem is of > course more noticeable for unlogged tables since they're not hidden > away in a special funny schema.
Seems like you're trying to fix the problem directly, which as you say, has problems. At some point we resolve from a word mentioned in the FROM clause to a relfilenode. Surely somewhere there we can notice its unlogged before we end up down in the guts of smgr? -- Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-bugs mailing list (pgsql-bugs@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-bugs
