Re: Combination of ordered-set aggregate function terminates JDBC connection on PostgreSQL 9.6.5

Tom Lane <tgl@sss.pgh.pa.us>

From: Tom Lane <tgl@sss.pgh.pa.us>

To: David Rowley <david.rowley@2ndquadrant.com>

Cc: Lukas Eder <lukas.eder@gmail.com>, PostgreSQL mailing lists <pgsql-bugs@postgresql.org>, Heikki Linnakangas <hlinnaka@iki.fi>

Date: 2017-10-14T20:51:32Z

Lists: pgsql-bugs

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

Treat aggregate direct arguments as per-agg data not per-trans data.
- cf5ba7c30c04 11.0 landed
Allow the built-in ordered-set aggregates to share transition state.
- be0ebb65f512 11.0 landed
Fix AggGetAggref() so it won't lie to aggregate final functions.
- 305cf1fd7239 11.0 landed
- d48bf6a94d29 10.1 landed
- aa1e9b3a4661 9.6.6 landed
Prevent sharing transition states between ordered-set aggregates.
- 52328727bea4 11.0 landed
- 96cfc7e19ae1 9.6.6 landed
- 604723d29a86 10.1 landed

Attachments

allow-state-merging-in-builtin-OSAs.patch (text/x-diff) patch

I wrote:
> To know what value of randomAccess to pass to the tuplesort setup,
> we have to know *at the first transition-function call* whether
> there may be multiple final-function calls coming up.  So what
> what I'm imagining is a simple boolean result "yes, there will be
> only one finalfn call, so it can destructively modify the transition
> state", or "there might be more than one finalfn call, so the finalfn(s)
> must preserve transition state".  And this info has to be available
> throughout the aggregate run.

Attached is a proposed patch to make the ordered-set aggregates
safe for state merging.  I've not tested it really thoroughly,
but it passes the regression cases added in 52328727b.

			regards, tom lane