MDEV-30221: Move environmental macros to before master-slave
The fix was introduced, along with re-ordering to do other macros that check test environment capabilities before master/slave is set up.
MDEV-31067: selectivity_from_histogram >1.0 for a DOUBLE_PREC_HB histogram
Variant #2.
When Histogram::point_selectivity() sees that the point value of interest
falls into one bucket, it tries to guess whether the bucket has many
different (unpopular) values or a few popular values. (The number of
rows is fixed, as it's a Height-balanced histogram).
The basis for this guess is the "width" of the value range the bucket
covers. Buckets covering wider value ranges are assumed to contain
values with proportionally lower frequencies.
This is just a [brave] guesswork. For a very narrow bucket, it may
produce an estimate that's larger than total #rows in the bucket
or even in the whole table.
Remove the guesswork and replace it with basic logic: return
either the per-table average selectivity of col=const, or selectivity
of one bucket, whichever is lower.
MDEV-31113 Server crashes in store_length / Type_handler_string_result::make_sort_key with DISTINCT and group function
Fix-up for commit 476b24d084e7e717310155bb986eb086d3c1e1a6
Author: Monty
Date: Thu Feb 16 14:19:33 2023 +0200
MDEV-20057 Distinct SUM on CROSS JOIN and grouped returns wrong result
which misses initializing of sorder->suffix_length.
In this commit the initialization is implemented by passing
MY_ZEROFILL flag to the allocation of SORT_FIELD elements
