[postgis-devel] estimated_extent & pg_statistic

[Mark Cave-Ayland]

> -----Original Message-----
> From: postgis-devel-bounces at postgis.refractions.net [mailto:postgis-devel-
> bounces at postgis.refractions.net] On Behalf Of strk at refractions.net
> Sent: 27 February 2006 16:26
> To: 'PostGIS Development Discussion'
> Subject: Re: [postgis-devel] estimated_extent & pg_statistic

(cut)

> Adding the check makes sense to me, unless there's a special
> postgresql-provided view only showing stats on columns which are
> user-readable, which would be much better.
> 
> --strk;


Hi strk,

As far as I can tell, that is what the PostgreSQL pg_stats view does except:

	1) It only shows the stats which are for postgresql in-built stats
	(1 <= stakind <= 3)

	2) It attempts to interpret the statistics, for example extracting
	correlation and histogram extents from the pg_statistics table.
	Obviously, since our stats format is customized, the result would be
	just nonsense.

Perhaps we should consider adding a new postgis_stats() view to solve the
problem, and then tweak estimate_extent() to use that instead? A \d pg_stats
shows that the has_table_privilege() function should do the job fairly
easily.


Kind regards,

Mark.

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