Обсуждение: pgsql: Minor improvements for the multivariate MCV lists

Minor improvements for the multivariate MCV lists

The MCV build should always call get_mincount_for_mcv_list(), as the
there is no other logic to decide whether the MCV list represents all
the data. So just remove the (ngroups > nitems) condition.

Also, when building MCV lists, the number of items was limited by the
statistics target (i.e. up to 10000). But when deserializing the MCV
list, a different value (8192) was used to check the input, causing
an error.  Simply ensure that the same value is used in both places.

This should have been included in 7300a69950, but I forgot to include it
in that commit.

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/a63b29a1dea0ce4e95f682f9d0b36994f2fcf43e

Modified Files
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src/backend/statistics/mcv.c        | 64 ++++++++++++++++++-------------------
src/include/statistics/statistics.h |  4 +--
2 files changed, 33 insertions(+), 35 deletions(-)