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Yuchen Pei 8cdee25952
MDEV-36132 Substitute vcol expressions with indexed vcol fields in ORDER BY and GROUP BY
Also expand vcol field index coverings to include indexes covering all
the fields in the expression. The reasoning goes as follows: let f(c1,
c2, ..., cn) be a function on applied to columns c1, c2, ..., cn, if
f(...) is covered by an index, so should vc whose expression is
f(...).

For example, if t.vf = t.c1 + t.c2, and t has three indexes (vf), (c1,
c2), (c1).

Before this change, vf's index covering is a singleton {(vf)}. Let's call
that the "conventional" index covering.

After this change vf's index covering is now {(vf), (c1, c2)}, since
(c1, c2) covers both c1 and c2. Let's call (c1, c2) in this case the
"extra" covering.

With the coverings updated, when an index in the "extra" covering is
chosen for keyread, the vcol also needs to be calculated. In this case
we mark vcol in the table read_set, and ensure it is computed.

With these changes, we see various improvements, including from using
full table scan + filesort to full index scan + filesort when ORDER BY
an indexed vcol (here vc = c + 1 is a vcol and both c and vc are
indexes):

 explain select c + 1 from t order by vc;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t	ALL	NULL	NULL	NULL	NULL	10000	Using filesort
+1	SIMPLE	t	index	NULL	c	5	NULL	10000	Using index; Using filesort

The substitutions are followed updates to all_fields which include a
copy of the ORDER BY/GROUP BY item pointers, as well as corresponding
updates to ref_pointer_array so that the all_fields and
ref_pointer_array remain in sync.

Another, related change is the recomputation of table index covering
on substitutions. It not only reflects the correct table index
covering after the substitutions, but also improve executions where
the vcol index can be chosen, such as this example (here vc = c + 1
and vc is the only index in the table), from full table scan +
filesort to full index scan:

select vc from t order by c + 1;

We do it in SELECT as well as in single table DELETE/UPDATE.
2025-07-22 10:44:12 +10:00
.github Merge branch '11.8' into 12.0 2025-06-18 07:50:39 +02:00
BUILD Fix remaining typos 2025-04-29 11:18:00 +10:00
client mariadb-test: wait on disconnect 2025-07-16 09:14:33 +07:00
cmake Got rid of the INFO_BIN and INFO_SRC files 2025-07-10 18:18:24 +10:00
dbug Reënable ATTRIBUTE_FORMAT on DBUG_PRINT & t/eprint 2025-02-12 10:17:44 +01:00
debian Merge branch '12.0' into 12.1 2025-06-05 12:01:25 +02:00
Docs Fix remaining typos 2025-04-29 11:18:00 +10:00
extra MDEV-24 Segmented key cache for Aria 2025-06-25 17:59:45 +03:00
include MDEV-24 Segmented key cache for Aria 2025-06-25 17:59:45 +03:00
libmariadb@b5a2c9f3c2 new CC 2025-04-20 21:54:17 +02:00
libmysqld MDEV-36397 Record change_user command in MTR output 2025-06-23 20:38:36 +02:00
libservices Merge 10.6 into 10.11 2024-02-08 15:04:46 +02:00
man Merge branch '11.8' into 12.0 2025-06-18 07:50:39 +02:00
mysql-test MDEV-36132 Substitute vcol expressions with indexed vcol fields in ORDER BY and GROUP BY 2025-07-22 10:44:12 +10:00
mysys Fixed some compilation failures on 32bit 2025-06-25 17:59:45 +03:00
mysys_ssl MDEV-34712 Add support to sha2 and pbkdf2 key derivation in file_key_management 2025-04-28 13:43:32 +10:00
plugin cleanup: disconnect before DROP USER 2025-07-16 09:14:33 +07:00
randgen/conf Group commit for maria engine. 2010-02-12 15:12:28 +02:00
scripts MDEV-34954 Add JSON flag for mysqldumpslow.sh output 2025-07-10 19:15:01 +10:00
sql MDEV-36132 Substitute vcol expressions with indexed vcol fields in ORDER BY and GROUP BY 2025-07-22 10:44:12 +10:00
sql-bench Fix remaining typos 2025-04-29 11:18:00 +10:00
sql-common MDEV-31334: Consider dates ending in 'T' as malformed 2025-04-15 14:39:42 +03:00
storage MDEV-35617: DROP USER should leave no active session for that user 2025-07-16 09:14:33 +07:00
strings Merge branch '11.8' into 12.0 2025-06-18 07:50:39 +02:00
support-files Merge branch '11.8' into 12.0 2025-05-22 09:22:55 +02:00
tests Merge branch '11.8' into 12.0 2025-05-22 09:22:55 +02:00
tpool Merge branch '11.8' into 12.0 2025-05-22 09:22:55 +02:00
unittest Fix typos in C comments in miscellaneous files 2025-03-24 13:36:28 +11:00
vio Merge branch '11.8' into 12.0 2025-06-18 07:50:39 +02:00
win Merge branch '11.8' into 12.0 2025-05-22 09:22:55 +02:00
wsrep-lib@e55f01ce1e MDEV-36422 Build fails with cmake 4.0.0 due to wsrep 2025-04-10 13:05:19 +02:00
zlib Merge branch 'merge-zlib' (1.3.1) into 10.4 2024-04-26 13:50:03 +02:00
.clang-format Remove duplicate key "Language" from .clang-format 2024-04-17 16:52:37 +02:00
.gitattributes Merge branch '10.5' into 10.6 2022-02-03 17:01:31 +01:00
.gitignore Merge branch '11.4' into 11.8 2025-06-18 07:43:24 +02:00
.gitlab-ci.yml Fix remaining typos 2025-04-29 11:18:00 +10:00
.gitmodules Merge remote-tracking branch '10.4' into 10.5 2023-03-31 21:32:41 +02:00
appveyor.yml Merge remote-tracking branch 'github/bb-11.4-release' into bb-11.8-serg 2025-04-27 19:40:00 +02:00
BUILD-CMAKE Fix remaining typos 2025-04-29 11:18:00 +10:00
CMakeLists.txt Got rid of the INFO_BIN and INFO_SRC files 2025-07-10 18:18:24 +10:00
CODING_STANDARDS.md Merge branch '11.8' into 12.0 2025-06-18 07:50:39 +02:00
config.h.cmake Merge remote-tracking branch 'github/bb-11.4-release' into bb-11.8-serg 2025-04-27 19:40:00 +02:00
configure.cmake Merge branch '11.6' into 11.7 2024-11-10 19:22:21 +01:00
CONTRIBUTING.md Add CODING_STANDARDS.md file 2023-02-03 15:47:17 +11:00
COPYING Update FSF Address 2019-05-11 21:29:06 +03:00
CREDITS Update sponsors 2024-08-12 09:32:30 +01:00
INSTALL-SOURCE Update AskMonty and Atlassian references to MariaDB 2016-03-08 15:24:01 +02:00
INSTALL-WIN-SOURCE Update AskMonty and Atlassian references to MariaDB 2016-03-08 15:24:01 +02:00
KNOWN_BUGS.txt Changed some MySQL names in messages to MariaDB 2018-12-09 20:49:05 +02:00
README.md Merge branch '10.11' into 11.1 2024-05-31 10:54:31 +10:00
SECURITY.md Create SECURITY.md 2023-06-05 08:28:06 +10:00
THIRDPARTY Update THIRDPARTY license file to reflect reality 2025-04-18 23:16:46 +02:00
VERSION bump the VERSION 2025-06-04 09:39:02 -04:00

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