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bug #27531: 5.1 part of the fix:

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- added join cache indication in EXPLAIN (Extra column).
 - prefer filesort over full scan over 
   index for ORDER BY (because it's faster).
 - when switching from REF to RANGE because
   RANGE uses longer key turn off sort on
   the head table only as the resulting 
   RANGE access is a candidate for join cache
   and we don't want to disable it by sorting
   on the first table only.
This commit is contained in:
gkodinov/kgeorge@magare.gmz
2007-05-04 18:06:06 +03:00
parent 19b9c7a8cd
commit 306371a850
31 changed files with 216 additions and 202 deletions
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4
mysql-test/r/innodb_mysql.result
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@ -163,7 +163,7 @@ min(7)
7
explain select min(7) from t2i join t1i;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2i ALL NULL NULL NULL NULL 1
1 SIMPLE t2i ALL NULL NULL NULL NULL 1 Using join cache
1 SIMPLE t1i ALL NULL NULL NULL NULL 1
select min(7) from t2i join t1i;
min(7)
@ -179,7 +179,7 @@ max(7)
7
explain select max(7) from t2i join t1i;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2i ALL NULL NULL NULL NULL 1
1 SIMPLE t2i ALL NULL NULL NULL NULL 1 Using join cache
1 SIMPLE t1i ALL NULL NULL NULL NULL 1
select max(7) from t2i join t1i;
max(7)