From ae480437ce98bbba8624e52833b8edbcc495b014 Mon Sep 17 00:00:00 2001 From: Sergey Petrunya Date: Thu, 8 Dec 2011 04:22:38 +0400 Subject: [PATCH] Small semi-join optimization improvement: - if we're considering FirstMatch access with one inner table, and @@optimizer_switch has semijoin_with_cache flag, calculate costs as if we used join cache (because we will be able to do so) --- mysql-test/r/subselect.result | 4 ++-- mysql-test/r/subselect3.result | 6 +++--- mysql-test/r/subselect3_jcl6.result | 10 ++++----- mysql-test/r/subselect4.result | 8 ++++---- mysql-test/r/subselect_extra.result | 13 ++++++------ mysql-test/r/subselect_no_mat.result | 4 ++-- mysql-test/r/subselect_no_scache.result | 4 ++-- mysql-test/r/subselect_sj2_jcl6.result | 3 +-- mysql-test/r/subselect_sj_jcl6.result | 27 ++++++++++--------------- sql/opt_subselect.cc | 26 ++++++++++++++++++------ 10 files changed, 56 insertions(+), 49 deletions(-) diff --git a/mysql-test/r/subselect.result b/mysql-test/r/subselect.result index 0a4a16962ff..a31a6b6c3cf 100644 --- a/mysql-test/r/subselect.result +++ b/mysql-test/r/subselect.result @@ -5205,8 +5205,8 @@ INSERT INTO t2 VALUES (15,4); EXPLAIN SELECT * FROM t1 WHERE pk IN (SELECT it.pk FROM t2 JOIN t2 AS it ON 1); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 ALL PRIMARY NULL NULL NULL 3 -1 PRIMARY t2 index NULL PRIMARY 4 NULL 3 Using index; Start temporary; Using join buffer (flat, BNL join) -1 PRIMARY it eq_ref PRIMARY PRIMARY 4 test.t1.pk 1 Using index; End temporary +1 PRIMARY it eq_ref PRIMARY PRIMARY 4 test.t1.pk 1 Using index +1 PRIMARY t2 index NULL PRIMARY 4 NULL 3 Using index; FirstMatch(it); Using join buffer (flat, BNL join) SELECT * FROM t1 WHERE pk IN (SELECT it.pk FROM t2 JOIN t2 AS it ON 1); pk i 11 0 diff --git a/mysql-test/r/subselect3.result b/mysql-test/r/subselect3.result index 898eed164b7..7d13bce1f85 100644 --- a/mysql-test/r/subselect3.result +++ b/mysql-test/r/subselect3.result @@ -105,7 +105,7 @@ oref a 1 1 show status like '%Handler_read_rnd_next'; Variable_name Value -Handler_read_rnd_next 14 +Handler_read_rnd_next 5 delete from t2; insert into t2 values (NULL, 0),(NULL, 0), (NULL, 0), (NULL, 0); set optimizer_switch='subquery_cache=off'; @@ -1308,7 +1308,7 @@ insert into t1 select * from t0; explain select * from t0 where a in (select a from t1); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t0 ALL NULL NULL NULL NULL 2 -1 PRIMARY t1 ALL NULL NULL NULL NULL 4 Using where; Start temporary; End temporary; Using join buffer (flat, BNL join) +1 PRIMARY t1 ALL NULL NULL NULL NULL 4 Using where; FirstMatch(t0); Using join buffer (flat, BNL join) select * from t0 where a in (select a from t1); a 10.24 @@ -1321,7 +1321,7 @@ insert into t1 select * from t0; explain select * from t0 where a in (select a from t1); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t0 ALL NULL NULL NULL NULL 2 -1 PRIMARY t1 ALL NULL NULL NULL NULL 4 Using where; Start temporary; End temporary; Using join buffer (flat, BNL join) +1 PRIMARY t1 ALL NULL NULL NULL NULL 4 Using where; FirstMatch(t0); Using join buffer (flat, BNL join) select * from t0 where a in (select a from t1); a 2008-01-01 diff --git a/mysql-test/r/subselect3_jcl6.result b/mysql-test/r/subselect3_jcl6.result index 59750f2cfa0..5ad5878623d 100644 --- a/mysql-test/r/subselect3_jcl6.result +++ b/mysql-test/r/subselect3_jcl6.result @@ -114,7 +114,7 @@ oref a 1 1 show status like '%Handler_read_rnd_next'; Variable_name Value -Handler_read_rnd_next 14 +Handler_read_rnd_next 5 delete from t2; insert into t2 values (NULL, 0),(NULL, 0), (NULL, 0), (NULL, 0); set optimizer_switch='subquery_cache=off'; @@ -1316,8 +1316,8 @@ create table t1 as select * from t0; insert into t1 select * from t0; explain select * from t0 where a in (select a from t1); id select_type table type possible_keys key key_len ref rows Extra -1 PRIMARY t0 ALL NULL NULL NULL NULL 2 Using where -1 PRIMARY t1 hash_ALL NULL #hash#$hj 3 test.t0.a 4 Using where; Start temporary; End temporary; Using join buffer (flat, BNLH join) +1 PRIMARY t0 ALL NULL NULL NULL NULL 2 +1 PRIMARY t1 ALL NULL NULL NULL NULL 4 Using where; FirstMatch(t0); Using join buffer (flat, BNL join) select * from t0 where a in (select a from t1); a 10.24 @@ -1329,8 +1329,8 @@ create table t1 as select * from t0; insert into t1 select * from t0; explain select * from t0 where a in (select a from t1); id select_type table type possible_keys key key_len ref rows Extra -1 PRIMARY t0 ALL NULL NULL NULL NULL 2 Using where -1 PRIMARY t1 hash_ALL NULL #hash#$hj 4 test.t0.a 4 Using where; Start temporary; End temporary; Using join buffer (flat, BNLH join) +1 PRIMARY t0 ALL NULL NULL NULL NULL 2 +1 PRIMARY t1 ALL NULL NULL NULL NULL 4 Using where; FirstMatch(t0); Using join buffer (flat, BNL join) select * from t0 where a in (select a from t1); a 2008-01-01 diff --git a/mysql-test/r/subselect4.result b/mysql-test/r/subselect4.result index 76496d73ef9..f830be38321 100644 --- a/mysql-test/r/subselect4.result +++ b/mysql-test/r/subselect4.result @@ -1230,16 +1230,16 @@ EXPLAIN SELECT * FROM t1 RIGHT JOIN t2 ON t1.c1 WHERE 's' IN (SELECT c1 FROM t2); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 system NULL NULL NULL NULL 0 const row not found -1 PRIMARY t2 ALL NULL NULL NULL NULL 2 Using where; FirstMatch(t1) -1 PRIMARY t2 ALL NULL NULL NULL NULL 2 Using join buffer (flat, BNL join) +1 PRIMARY t2 ALL NULL NULL NULL NULL 2 +1 PRIMARY t2 ALL NULL NULL NULL NULL 2 Using where; FirstMatch(t2); Using join buffer (flat, BNL join) SELECT * FROM t1 RIGHT JOIN t2 ON t1.c1 WHERE 's' IN (SELECT c1 FROM t2); c1 c1 EXPLAIN SELECT * FROM t2 LEFT JOIN t1 ON t1.c1 WHERE 's' IN (SELECT c1 FROM t2); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 system NULL NULL NULL NULL 0 const row not found -1 PRIMARY t2 ALL NULL NULL NULL NULL 2 Using where; FirstMatch(t1) -1 PRIMARY t2 ALL NULL NULL NULL NULL 2 Using join buffer (flat, BNL join) +1 PRIMARY t2 ALL NULL NULL NULL NULL 2 +1 PRIMARY t2 ALL NULL NULL NULL NULL 2 Using where; FirstMatch(t2); Using join buffer (flat, BNL join) SELECT * FROM t2 LEFT JOIN t1 ON t1.c1 WHERE 's' IN (SELECT c1 FROM t2); c1 c1 EXPLAIN diff --git a/mysql-test/r/subselect_extra.result b/mysql-test/r/subselect_extra.result index 23c4849b120..9246128391e 100644 --- a/mysql-test/r/subselect_extra.result +++ b/mysql-test/r/subselect_extra.result @@ -16,7 +16,7 @@ flush tables; EXPLAIN SELECT OUTR.dt FROM t1 AS OUTR WHERE OUTR.dt IN (SELECT INNR.dt FROM t2 AS INNR WHERE OUTR.dt IS NULL ); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY OUTR ALL NULL NULL NULL NULL 2 Using where -1 PRIMARY INNR ALL NULL NULL NULL NULL 2 Using where; Start temporary; End temporary; Using join buffer (flat, BNL join) +1 PRIMARY INNR ALL NULL NULL NULL NULL 2 Using where; FirstMatch(OUTR); Using join buffer (flat, BNL join) flush tables; SELECT OUTR.dt FROM t1 AS OUTR WHERE OUTR.dt IN (SELECT INNR.dt FROM t2 AS INNR WHERE OUTR.dt IS NULL ); dt @@ -24,7 +24,7 @@ flush tables; EXPLAIN SELECT OUTR.dt FROM t1 AS OUTR WHERE OUTR.dt IN ( SELECT INNR.dt FROM t2 AS INNR WHERE OUTR.t < '2005-11-13 7:41:31' ); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY OUTR ALL NULL NULL NULL NULL 2 Using where -1 PRIMARY INNR ALL NULL NULL NULL NULL 2 Using where; Start temporary; End temporary; Using join buffer (flat, BNL join) +1 PRIMARY INNR ALL NULL NULL NULL NULL 2 Using where; FirstMatch(OUTR); Using join buffer (flat, BNL join) flush tables; SELECT OUTR.dt FROM t1 AS OUTR WHERE OUTR.dt IN ( SELECT INNR.dt FROM t2 AS INNR WHERE OUTR.t < '2005-11-13 7:41:31' ); dt @@ -68,7 +68,7 @@ select * from t1 where id in (select id from t1 as x1 where (t1.cur_date is null)); id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t1 ALL NULL NULL NULL NULL 2 100.00 Using where -1 PRIMARY x1 ALL NULL NULL NULL NULL 2 100.00 Using where; Start temporary; End temporary; Using join buffer (flat, BNL join) +1 PRIMARY x1 ALL NULL NULL NULL NULL 2 100.00 Using where; FirstMatch(t1); Using join buffer (flat, BNL join) Warnings: Note 1276 Field or reference 'test.t1.cur_date' of SELECT #2 was resolved in SELECT #1 Note 1003 select `test`.`t1`.`id` AS `id`,`test`.`t1`.`cur_date` AS `cur_date` from `test`.`t1` semi join (`test`.`t1` `x1`) where ((`test`.`x1`.`id` = `test`.`t1`.`id`) and (`test`.`t1`.`cur_date` = 0)) @@ -80,7 +80,7 @@ select * from t2 where id in (select id from t2 as x1 where (t2.cur_date is null)); id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 2 100.00 Using where -1 PRIMARY x1 ALL NULL NULL NULL NULL 2 100.00 Using where; Start temporary; End temporary; Using join buffer (flat, BNL join) +1 PRIMARY x1 ALL NULL NULL NULL NULL 2 100.00 Using where; FirstMatch(t2); Using join buffer (flat, BNL join) Warnings: Note 1276 Field or reference 'test.t2.cur_date' of SELECT #2 was resolved in SELECT #1 Note 1003 select `test`.`t2`.`id` AS `id`,`test`.`t2`.`cur_date` AS `cur_date` from `test`.`t2` semi join (`test`.`t2` `x1`) where ((`test`.`x1`.`id` = `test`.`t2`.`id`) and (`test`.`t2`.`cur_date` = 0)) @@ -307,8 +307,7 @@ EXPLAIN SELECT 1 FROM t1 WHERE a IN (SELECT a FROM t1 USE INDEX (i2) IGNORE INDEX (i2)); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 index PRIMARY,i2 PRIMARY 4 NULL 144 Using index -1 PRIMARY eq_ref distinct_key distinct_key 4 func 1 -2 MATERIALIZED t1 ALL NULL NULL NULL NULL 144 +1 PRIMARY t1 ALL NULL NULL NULL NULL 144 Using where; FirstMatch(t1); Using join buffer (flat, BNL join) CREATE TABLE t2 (a INT, b INT, KEY(a)); INSERT INTO t2 VALUES (1, 1), (2, 2), (3,3), (4,4); EXPLAIN SELECT a, SUM(b) FROM t2 GROUP BY a LIMIT 2; @@ -432,7 +431,7 @@ WHERE t2.c = v1.c AND t2.c = v1.b AND v1.b = t3.c); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t2 system NULL NULL NULL NULL 1 1 PRIMARY t3 ALL NULL NULL NULL NULL 2 Using where -1 PRIMARY ALL NULL NULL NULL NULL 3 Using where; Start temporary; End temporary; Using join buffer (flat, BNL join) +1 PRIMARY ALL NULL NULL NULL NULL 3 Using where; FirstMatch(t3); Using join buffer (flat, BNL join) 3 DERIVED t1 ALL NULL NULL NULL NULL 3 SELECT * FROM t3 WHERE t3.b IN (SELECT v1.b FROM v1, t2 diff --git a/mysql-test/r/subselect_no_mat.result b/mysql-test/r/subselect_no_mat.result index 01b83916c4b..3a184cb0a54 100644 --- a/mysql-test/r/subselect_no_mat.result +++ b/mysql-test/r/subselect_no_mat.result @@ -5204,8 +5204,8 @@ INSERT INTO t2 VALUES (15,4); EXPLAIN SELECT * FROM t1 WHERE pk IN (SELECT it.pk FROM t2 JOIN t2 AS it ON 1); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 ALL PRIMARY NULL NULL NULL 3 -1 PRIMARY t2 index NULL PRIMARY 4 NULL 3 Using index; Start temporary; Using join buffer (flat, BNL join) -1 PRIMARY it eq_ref PRIMARY PRIMARY 4 test.t1.pk 1 Using index; End temporary +1 PRIMARY it eq_ref PRIMARY PRIMARY 4 test.t1.pk 1 Using index +1 PRIMARY t2 index NULL PRIMARY 4 NULL 3 Using index; FirstMatch(it); Using join buffer (flat, BNL join) SELECT * FROM t1 WHERE pk IN (SELECT it.pk FROM t2 JOIN t2 AS it ON 1); pk i 11 0 diff --git a/mysql-test/r/subselect_no_scache.result b/mysql-test/r/subselect_no_scache.result index 606a19fa500..31d1c61a014 100644 --- a/mysql-test/r/subselect_no_scache.result +++ b/mysql-test/r/subselect_no_scache.result @@ -5209,8 +5209,8 @@ INSERT INTO t2 VALUES (15,4); EXPLAIN SELECT * FROM t1 WHERE pk IN (SELECT it.pk FROM t2 JOIN t2 AS it ON 1); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 ALL PRIMARY NULL NULL NULL 3 -1 PRIMARY t2 index NULL PRIMARY 4 NULL 3 Using index; Start temporary; Using join buffer (flat, BNL join) -1 PRIMARY it eq_ref PRIMARY PRIMARY 4 test.t1.pk 1 Using index; End temporary +1 PRIMARY it eq_ref PRIMARY PRIMARY 4 test.t1.pk 1 Using index +1 PRIMARY t2 index NULL PRIMARY 4 NULL 3 Using index; FirstMatch(it); Using join buffer (flat, BNL join) SELECT * FROM t1 WHERE pk IN (SELECT it.pk FROM t2 JOIN t2 AS it ON 1); pk i 11 0 diff --git a/mysql-test/r/subselect_sj2_jcl6.result b/mysql-test/r/subselect_sj2_jcl6.result index 8fd9122465c..02d2fb01d93 100644 --- a/mysql-test/r/subselect_sj2_jcl6.result +++ b/mysql-test/r/subselect_sj2_jcl6.result @@ -76,8 +76,7 @@ insert into t3 select a,a, a+100,a+100,a+100 from t0; explain select * from t3 where b in (select a from t1); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t3 ALL b NULL NULL NULL 20 -1 PRIMARY eq_ref distinct_key distinct_key 5 func 1 -2 MATERIALIZED t1 ALL NULL NULL NULL NULL 3 +1 PRIMARY t1 ALL NULL NULL NULL NULL 3 Using where; FirstMatch(t3); Using join buffer (flat, BNL join) select * from t3 where b in (select a from t1); a b pk1 pk2 pk3 1 1 1 1 1 diff --git a/mysql-test/r/subselect_sj_jcl6.result b/mysql-test/r/subselect_sj_jcl6.result index 03940e0e5eb..2f0db469bd9 100644 --- a/mysql-test/r/subselect_sj_jcl6.result +++ b/mysql-test/r/subselect_sj_jcl6.result @@ -979,10 +979,9 @@ FROM t1 WHERE `varchar_nokey` < 'n' XOR `pk` ) ; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 18 100.00 -1 PRIMARY eq_ref distinct_key distinct_key 8 func,func 1 100.00 -2 MATERIALIZED t1 ALL varchar_key NULL NULL NULL 15 100.00 Using where +1 PRIMARY t1 ref varchar_key varchar_key 3 test.t2.varchar_nokey 2 100.00 Using where; FirstMatch(t2); Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan Warnings: -Note 1003 select `test`.`t2`.`varchar_nokey` AS `varchar_nokey` from `test`.`t2` semi join (`test`.`t1`) where ((`test`.`t1`.`varchar_nokey` = `test`.`t1`.`varchar_key`) and ((`test`.`t1`.`varchar_key` < 'n') xor `test`.`t1`.`pk`)) +Note 1003 select `test`.`t2`.`varchar_nokey` AS `varchar_nokey` from `test`.`t2` semi join (`test`.`t1`) where ((`test`.`t1`.`varchar_key` = `test`.`t2`.`varchar_nokey`) and (`test`.`t1`.`varchar_nokey` = `test`.`t2`.`varchar_nokey`) and ((`test`.`t2`.`varchar_nokey` < 'n') xor `test`.`t1`.`pk`)) SELECT varchar_nokey FROM t2 WHERE ( `varchar_nokey` , `varchar_nokey` ) IN ( @@ -1061,10 +1060,8 @@ AND t1.val IN (SELECT t3.val FROM t3 WHERE t3.val LIKE 'a%' OR t3.val LIKE 'e%'); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 ALL NULL NULL NULL NULL 5 -1 PRIMARY eq_ref distinct_key distinct_key 14 func 1 -1 PRIMARY eq_ref distinct_key distinct_key 14 func 1 -3 MATERIALIZED t3 ALL NULL NULL NULL NULL 5 Using where -2 MATERIALIZED t2 ALL NULL NULL NULL NULL 6 Using where +1 PRIMARY t3 ALL NULL NULL NULL NULL 5 Using where; FirstMatch(t1); Using join buffer (flat, BNL join) +1 PRIMARY t2 ALL NULL NULL NULL NULL 6 Using where; FirstMatch(t3); Using join buffer (incremental, BNL join) SELECT * FROM t1 WHERE t1.val IN (SELECT t2.val FROM t2 @@ -1254,7 +1251,7 @@ A.t1field IN (SELECT C.t2field FROM t2 C WHERE C.t2field IN (SELECT D.t2field FROM t2 D)); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY A index PRIMARY PRIMARY 4 NULL 3 Using index -1 PRIMARY B index NULL PRIMARY 4 NULL 3 Using index; Start temporary; End temporary; Using join buffer (flat, BNL join) +1 PRIMARY B index NULL PRIMARY 4 NULL 3 Using index; FirstMatch(A); Using join buffer (flat, BNL join) 1 PRIMARY C eq_ref PRIMARY PRIMARY 4 test.A.t1field 1 Using index 1 PRIMARY D eq_ref PRIMARY PRIMARY 4 test.A.t1field 1 Using index SELECT * FROM t1 A @@ -1283,11 +1280,9 @@ select * from t1 A, t1 B where A.a = B.a and A.a in (select a from t2 C) and B.a in (select a from t2 D); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY A ALL NULL NULL NULL NULL 3 -1 PRIMARY eq_ref distinct_key distinct_key 5 func 1 1 PRIMARY B ALL NULL NULL NULL NULL 3 Using where; Using join buffer (flat, BNL join) -1 PRIMARY eq_ref distinct_key distinct_key 5 func 1 -2 MATERIALIZED C ALL NULL NULL NULL NULL 3 -3 MATERIALIZED D ALL NULL NULL NULL NULL 3 +1 PRIMARY C ALL NULL NULL NULL NULL 3 Using where; FirstMatch(B); Using join buffer (incremental, BNL join) +1 PRIMARY D ALL NULL NULL NULL NULL 3 Using where; FirstMatch(C); Using join buffer (incremental, BNL join) drop table t1, t2; # # BUG#784441: Abort on semijoin with a view as the inner table @@ -2160,8 +2155,8 @@ SELECT * FROM t1, t2 WHERE t2.a IN (SELECT b FROM t3 WHERE t3.d <= t1.a); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 ALL NULL NULL NULL NULL 2 -1 PRIMARY t3 ALL d NULL NULL NULL 5 Range checked for each record (index map: 0x2); Start temporary -1 PRIMARY t2 hash_ALL PRIMARY #hash#PRIMARY 4 test.t3.b 4 End temporary; Using join buffer (flat, BNLH join) +1 PRIMARY t2 ALL PRIMARY NULL NULL NULL 4 Using join buffer (flat, BNL join) +1 PRIMARY t3 ALL d NULL NULL NULL 5 Range checked for each record (index map: 0x2); FirstMatch(t2) SELECT * FROM t1, t2 WHERE t2.a IN (SELECT b FROM t3 WHERE t3.d <= t1.a); a a b @@ -2175,8 +2170,8 @@ SELECT * FROM t1, t2 WHERE t2.a IN (SELECT b FROM t3 WHERE t3.d <= t1.a); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 ALL NULL NULL NULL NULL 2 -1 PRIMARY t3 ALL d NULL NULL NULL 5 Range checked for each record (index map: 0x2); Start temporary -1 PRIMARY t2 eq_ref PRIMARY PRIMARY 4 test.t3.b 1 End temporary; Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan +1 PRIMARY t2 ALL PRIMARY NULL NULL NULL 4 Using join buffer (flat, BNL join) +1 PRIMARY t3 ALL d NULL NULL NULL 5 Range checked for each record (index map: 0x2); FirstMatch(t2) SELECT * FROM t1, t2 WHERE t2.a IN (SELECT b FROM t3 WHERE t3.d <= t1.a); a a b diff --git a/sql/opt_subselect.cc b/sql/opt_subselect.cc index 233305f3da6..46ecb5ff65a 100644 --- a/sql/opt_subselect.cc +++ b/sql/opt_subselect.cc @@ -2617,13 +2617,27 @@ bool Firstmatch_picker::check_qep(JOIN *join, !(firstmatch_need_tables & remaining_tables)) { /* - Got a complete FirstMatch range. - Calculate correct costs and fanout + Got a complete FirstMatch range. Calculate correct costs and fanout */ - optimize_wo_join_buffering(join, first_firstmatch_table, idx, - remaining_tables, FALSE, idx, - record_count, - read_time); + + if (idx == first_firstmatch_table && + optimizer_flag(join->thd, OPTIMIZER_SWITCH_SEMIJOIN_WITH_CACHE)) + { + /* + An important special case: only one inner table, and @@optimizer_switch + allows join buffering. + - read_time is the same (i.e. FirstMatch doesn't add any cost + - remove fanout added by the last table + */ + *record_count /= join->positions[idx].records_read; + } + else + { + optimize_wo_join_buffering(join, first_firstmatch_table, idx, + remaining_tables, FALSE, idx, + record_count, + read_time); + } /* We ought to save the alternate POSITIONs produced by optimize_wo_join_buffering but the problem is that providing save