Re: [HACKERS] PATCH: multivariate histograms and MCV lists

On 08/17/2017 12:06 PM, Adrien Nayrat wrote:>
> Hello,
> 
> There is no check of "statistics type/kind" in
> pg_stats_ext_mcvlist_items and pg_histogram_buckets.
> 
> select stxname,stxkind from pg_statistic_ext ; stxname  | stxkind 
> -----------+--------- stts3     | {h} stts2     | {m}
> 
> So you can call :
> 
> SELECT * FROM pg_mcv_list_items((SELECT oid FROM pg_statistic_ext
> WHERE stxname = 'stts3'));
> 
> SELECT * FROM pg_histogram_buckets((SELECT oid FROM pg_statistic_ext
> WHERE stxname = 'stts2'), 0);
> 
> Both crashes.
> 

Thanks for the report, this is clearly a bug. I don't think we need to
test the stxkind, but rather a missing check that the requested type is
actually built.

> Unfotunately, I don't have the knowledge to produce a patch :/
> 
> Small fix in documentation, patch attached.
> 

Thanks, will fix.

regards

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
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