Tom Lane <tgl@xxxxxxxxxxxxx> schrieb: >Andres Freund <andres@xxxxxxxxxxxxxxx> writes: >> On 2013-04-25 13:17:31 -0400, Tom Lane wrote: >>> Since we know that C.I.C. executes in its own transaction, and there >>> can't be more than one on the same table due to locking, it seems to >me >>> that it'd be safe to drop our own snapshot before waiting for other >>> xacts to end. That is, we could just rearrange the last few steps >in >>> DefineIndex(), taking care to save snapshot->xmin before we destroy >the >>> snapshot so that we still have that value to pass to >>> GetCurrentVirtualXIDs(). >>> >>> Anybody see a flaw in that solution? > >> Except that it still will unnecessarily wait for other CICs, just not >> deadlock, I don't see a problem. We could have a PROC_IN_CIC flag or >> something so we can ignore other index creations, but I am not sure >if >> its worth the complication. > >I'm not sure it's a good idea to ignore other CICs altogether --- they >could be executing user-defined index functions that do strange things >like consult other tables. Since this seems to me to be a bit outside >the intended use-case for CIC anyway, I think it's good enough if they >just don't deadlock Fine with me, especially as nobody seems to have complained so far other than the OP, so it doesn't seem to be to common. I don't have access to the code ATM an I wonder whether DROP CONCURRENTLY has a similar problem? Depends a bit on how the waiting is done... Andres --- Please excuse brevity and formatting - I am writing this on my mobile phone. -- Sent via pgsql-admin mailing list (pgsql-admin@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-admin
