Re: BUG #19686: Rolling back SET TABLESPACE

Andres Freund <andres(at)anarazel(dot)de> writes:
> I wonder if we should try to apply two optimizations, even in the back
> branches:

> 1) don't copy indexes if the SET TABLESPACE is executed at the top-level

> 2) Avoid the index copy if the index has been created in the current
> subtransaction.

+1 to both things, doesn't seem too difficult. (1) probably covers
the majority of existing usage --- else, we'd have noticed this
problem a long time ago.

>> The one disadvantage I see is that (I imagine) a common use-case is
>> to move both a table and its indexes to a new tablespace, and this
>> solution will imply that that sequence double-copies the indexes.
>> Maybe it'd be worth providing a command variant that copies the
>> table and its indexes to a new tablespace in one step. But that
>> is a future optimization, not part of the bug fix; and I could be
>> wrong about whether anyone even cares.

> With the 2) from above, that could then be achieved by having a transaction
> first move the indexes and then the table itself. Probably not as good as a
> command doing both, but it can be done without a new syntax...q

Agreed, that at least provides a workaround.

regards, tom lane