Re: Index build temp files

* Bruce Momjian (bruce(at)momjian(dot)us) wrote:
> On Tue, Jan 8, 2013 at 05:09:47PM -0500, Stephen Frost wrote:
> > Greetings,
> >
> > We were surprised recently to note that the temp files that are
> > created during a CREATE INDEX don't go into either a temp tablespace
> > set for the user or into the tablespace which the CREATE INDEX
> > specifies. Instead, they go only into base/pgsql_tmp/. This doesn't
> > allow for any flexibility in defining where to create these
> > potentially quite large sets of files.
> >
> > Shouldn't these temp files be going into the temp tablespace for the
> > user creating the index instead..? Or perhaps into the tablespace
> > which the index is being created in?
>
> 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.

Thanks,

Stephen