Re: Re: pg_stat_statements normalisation without invasive changes to the parser (was: Next steps on pg_stat_statements normalisation)

Peter Geoghegan <peter@2ndquadrant.com>

From: Peter Geoghegan <peter@2ndquadrant.com>

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

Cc: Robert Haas <robertmhaas@gmail.com>, PG Hackers <pgsql-hackers@postgresql.org>

Date: 2012-04-08T23:00:34Z

Lists: pgsql-hackers

Commits

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

Restructure SELECT INTO's parsetree representation into CreateTableAsStmt.
- 9dbf2b7d75de 9.2.0 cited
Extend the parser location infrastructure to include a location field in
- a2794623d292 8.4.0 cited
Teach eval_const_expressions() to simplify an ArrayCoerceExpr to a constant
- 6734182c169a 8.4.0 cited

Attachments

pg_stat_statements_optimization_2012_04_08.patch (application/octet-stream) patch

On 8 April 2012 20:51, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Applied with some cosmetic adjustments.

Thanks.

Having taken another look at the code, I wonder if we wouldn't have
been better off just fastpathing out of pgss_store in the first call
(in a pair of calls made by a backend as part an execution of some
non-prepared query) iff there is already an entry in the hashtable -
after all, we're now going to the trouble of acquiring the spinlock
just to increment the usage for the entry by 0 (likewise, every other
field), which is obviously superfluous. I apologise for not having
spotted this before submitting my last patch.

I have attached a patch with the modifications described.

This is more than a micro-optimisation, since it will cut the number
of spinlock acquisitions approximately in half for non-prepared
queries.

-- 
Peter Geoghegan       http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training and Services