MDEV-16188 Use in-memory PK filters built from range index scans

This patch contains a full implementation of the optimization
that allows to use in-memory rowid / primary filters built for range  
conditions over indexes. In many cases usage of such filters reduce  
the number of disk seeks spent for fetching table rows.

In this implementation the choice of what possible filter to be applied  
(if any) is made purely on cost-based considerations.

This implementation re-achitectured the partial implementation of
the feature pushed by Galina Shalygina in the commit
8d5a11122c32f4d9eb87536886c6e893377bdd07.

Besides this patch contains a better implementation of the generic  
handler function handler::multi_range_read_info_const() that
takes into account gaps between ranges when calculating the cost of
range index scans. It also contains some corrections of the
implementation of the handler function records_in_range() for MyISAM.

This patch supports the feature for InnoDB and MyISAM.

1 files changed, 6 insertions, 2 deletions

diff --git a/mysql-test/main/partition_range.result b/mysql-test/main/partition_range.result
index 7ae029d488c..2a79e01566d 100644
--- a/mysql-test/main/partition_range.result
+++ b/mysql-test/main/partition_range.result
@@ -958,13 +958,17 @@ INSERT INTO t1 SELECT a + 10, b + 10 FROM t1;
 INSERT INTO t1 SELECT a + 20, b + 20 FROM t1;
 INSERT INTO t1 SELECT a + 40, b + 40 FROM t1;
 INSERT INTO t2 SELECT * FROM t1;
+ANALYZE TABLE t1,t2;
+Table	Op	Msg_type	Msg_text
+test.t1	analyze	status	OK
+test.t2	analyze	status	Table is already up to date
 # plans should be identical
 EXPLAIN SELECT a, MAX(b) FROM t1 WHERE a IN (10,100) GROUP BY a;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	range	a	a	5	NULL	2	Using where; Using index
 EXPLAIN SELECT a, MAX(b) FROM t2 WHERE a IN (10,100) GROUP BY a;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t2	range	a	a	5	NULL	2	Using where; Using index for group-by
+1	SIMPLE	t2	range	a	a	5	NULL	2	Using where; Using index
 FLUSH status;
 SELECT a, MAX(b) FROM t1 WHERE a IN (10, 100) GROUP BY a;
 a	MAX(b)
@@ -980,5 +984,5 @@ a	MAX(b)
 # Should be no more than 4 reads.
 SHOW status LIKE 'handler_read_key';
 Variable_name	Value
-Handler_read_key	4
+Handler_read_key	2
 DROP TABLE t1, t2;