pgsql: Transform OR-clauses to SAOP's during index matching

Transform OR-clauses to SAOP's during index matching

This commit makes match_clause_to_indexcol() match
"(indexkey op C1) OR (indexkey op C2) ... (indexkey op CN)" expression
to the index while transforming it into "indexkey op ANY(ARRAY[C1, C2, ...])"
(ScalarArrayOpExpr node).

This transformation allows handling long OR-clauses with single IndexScan
avoiding diving them into a slower BitmapOr.

We currently restrict Ci to be either Const or Param to apply this
transformation only when it's clearly beneficial. However, in the future,
we might switch to a liberal understanding of constants, as it is in other
cases.

Discussion: https://postgr.es/m/567ED6CA.2040504%40sigaev.ru
Author: Alena Rybakina, Andrey Lepikhov, Alexander Korotkov
Reviewed-by: Peter Geoghegan, Ranier Vilela, Alexander Korotkov, Robert Haas
Reviewed-by: Jian He, Tom Lane, Nikolay Shaplov

Branch
------
master

Details
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https://git.postgresql.org/pg/commitdiff/d4378c0005e61b1bb78e88097ea6efcdddbe2d6e

Modified Files
--------------
src/backend/optimizer/path/indxpath.c | 284 ++++++++++++++++++++++++++++-
src/test/regress/expected/create_index.out | 270 +++++++++++++++++++++++++--
src/test/regress/expected/join.out | 57 +++++-
src/test/regress/expected/rowsecurity.out | 7 +
src/test/regress/expected/stats_ext.out | 12 ++
src/test/regress/expected/uuid.out | 31 ++++
src/test/regress/sql/create_index.sql | 69 +++++++
src/test/regress/sql/join.sql | 9 +
src/test/regress/sql/rowsecurity.sql | 1 +
src/test/regress/sql/stats_ext.sql | 3 +
src/test/regress/sql/uuid.sql | 12 ++
11 files changed, 732 insertions(+), 23 deletions(-)