d8cfa82d51
The regression tests for extended statistics were not testing a couple
of important cases for the MCV lists:
* IS NOT NULL clauses - We did have queries with IS NULL clauses, but
not the negative case.
* clauses with variable on the right - All the clauses had the Var on
the left, i.e. (Var op Const), so this adds (Const op Var) too.
* columns with fixed-length types passed by reference - All columns
were using either by-value or varlena types, so add a test with
UUID columns too. This matters for (de)serialization.
* NULL-only dimension - When one of the columns contains only NULL
values, we treat it a a special case during (de)serialization.
* arrays containing NULL - When the constant parameter contains NULL
value, we need to handle it correctly during estimation, for all
IN, ANY and ALL clauses.
Discussion: https://www.postgresql.org/message-id/flat/20200113230008.g67iyk4cs3xbnjju@development
Author: Tomas Vondra
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