Re: Index build temp files

Stephen Frost <sfrost@snowman.net> writes:
> * Bruce Momjian (bruce@momjian.us) wrote:
>> Well, our docs for temp_tablespaces says:
>> This variable specifies tablespaces in which to create temporary
>> objects (temp tables and indexes on temp tables) when a
>> <command>CREATE</> command does not explicitly specify a tablespace.
>> Temporary files for purposes such as sorting large data sets
>> are also created in these tablespaces.
>> 
>> Are you saying this is inaccorate?

> Yes and no?  Are the temporary files created during a CREATE INDEX
> considered "Temporary files for purposes such as sorting large data
> sets"?  My thinking is 'yes', but others may disagree.  Also,
> considering this a bug would imply that it's back-patchable and I'm not
> convinced it's worth the risk of breaking things which depend on the
> current behavior.

I don't think it's a bug.  What you seem to be proposing is that CREATE
INDEX ought to ignore temp_tablespaces and instead always put its temp
files in the tablespace where the finished index will reside.  This
would not be a good idea IMO --- allowing the temp files to be spread to
other tablespaces is better both from the standpoint of space usage and
the ability to overlap I/O.  (Admittedly, both of those concerns are
often theoretical, but if they are then I don't see why you'd care which
tablespace is used.)
        regards, tom lane