Hi,
On 11/25/2017 05:15 PM, Mark Dilger wrote:
>
>> On Nov 18, 2017, at 12:28 PM, Tomas Vondra <tomas.vondra@2ndquadrant.com> wrote:
>>
>> Hi,
>>
>> Attached is an updated version of the patch, adopting the psql describe
>> changes introduced by 471d55859c11b.
>>
>> regards
>>
>> --
>> Tomas Vondra http://www.2ndQuadrant.com
>> PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
>> <0001-multivariate-MCV-lists.patch.gz><0002-multivariate-histograms.patch.gz>
>
> Thanks, Tomas, again for your work on this feature.
>
> Applying just the 0001-multivariate-MCV-lists.patch to the current master, and
> then extending the stats_ext.sql test as follows, I am able to trigger an error,
> "ERROR: operator 4294934272 is not a valid ordering operator".
>
Ah, that's a silly bug ...
The code assumes that VacAttrStats->extra_data is always StdAnalyzeData,
and attempts to extract the ltopr from that. But for arrays that's of
course not true (array_typanalyze uses ArrayAnalyzeExtraData instead).
The reason why this only fails after the second INSERT is that we need
at least two occurrences of a value before considering it eligible for
MCV list. So after the first INSERT we don't even call the serialize.
Attached is a fix that should resolve this in MCV lists by looking up
the operator using lookup_type_cache() when serializing the MCV.
FWIW histograms have the same issue, but on more places (not just in
serialize, but also when building the histogram).
I'll send a properly updated patch series shortly, with tests checking
correct behavior with arrays.
Thanks for the report.
regards
--
Tomas Vondra http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
