Re: [HACKERS] Parallel Hash take II

Hi,

On 2017-11-27 22:25:12 +1300, Thomas Munro wrote:
Pushed 0003-Add-infrastructure-for-sharing-temporary-files-betwe.patch
after minor adjustments (some including conversing with you).

Changes:
- Changed an impossible elog() into an Assert().
- changed SharedFileSet->counter, and the backend static variable, to
uint32. Not impossible that a 32bit int overflows over the course of a
few weeks, and we a) imo shouldn't unnecessarily rely on signed
overflow being defined b) a negative number would look weird, even if
well defined (-fwrapv et al).
- Added a small comment about arbitrary-ness of the 8 in Oid
tablespaces[8].
- pgindent'ed

Questions:
- Right now RemovePgTempFilesInDir() will recurse into appropriately
named directories, and when it recurses it doesn't require the same
name pattern checks. I think that's good, but I think it'd be prudent
to be a bit more paranoid and prevent recursing into symlinked
subdirectories.
- As we don't clean temp files after crash-restarts it isn't impossible
to have a bunch of crash-restarts and end up with pids *and* per-pid
shared file set counters reused. Which'd lead to conflicts. Do we care?

Greetings,

Andres Freund