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Back-ported the patch of the mysql-5.6 code line that

Browse Source 
fixed several defects in the greedy optimization:

1) The greedy optimizer calculated the 'compare-cost' (CPU-cost)
   for iterating over the partial plan result at each level in
   the query plan as 'record_count / (double) TIME_FOR_COMPARE'

   This cost was only used locally for 'best' calculation at each
   level, and *not* accumulated into the total cost for the query plan.

   This fix added the 'CPU-cost' of processing 'current_record_count'
   records at each level to 'current_read_time' *before* it is used as
   'accumulated cost' argument to recursive 
   best_extension_by_limited_search() calls. This ensured that the
   cost of a huge join-fanout early in the QEP was correctly
   reflected in the cost of the final QEP.

   To get identical cost for a 'best' optimized query and a
   straight_join with the same join order, the same change was also
   applied to optimize_straight_join() and get_partial_join_cost()

2) Furthermore to get equal cost for 'best' optimized query and a
   straight_join the new code substrcated the same '0.001' in
   optimize_straight_join() as it had been already done in
   best_extension_by_limited_search()

3) When best_extension_by_limited_search() aggregated the 'best' plan a
   plan was 'best' by the check :

   'if ((search_depth == 1) || (current_read_time < join->best_read))'

   The term '(search_depth == 1' incorrectly caused a new best plan to be
   collected whenever the specified 'search_depth' was reached - even if
   this partial query plan was more expensive than what we had already
   found.
This commit is contained in:
Igor Babaev
2011-12-24 08:55:10 -08:00
parent 5d9fbc6177
commit 2b1f0b8757
40 changed files with 414 additions and 379 deletions
Download Patch File Download Diff File Expand all files Collapse all files

160
mysql-test/r/greedy_optimizer.result
View File

@@ -202,28 +202,28 @@ select @@optimizer_search_depth;
0
explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c12 = t2.c21 and t2.c22 = t3.c31 and t3.c32 = t4.c41 and t4.c42 = t5.c51 and t5.c52 = t6.c61 and t6.c62 = t7.c71;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 3
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where
1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t2.c22 1
1 SIMPLE t4 ALL NULL NULL NULL NULL 12 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t5 eq_ref PRIMARY PRIMARY 4 test.t4.c42 1
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t7 eq_ref PRIMARY PRIMARY 4 test.t6.c62 1 Using index
1 SIMPLE t1 ALL NULL NULL NULL NULL 3 Using where; Using join buffer (flat, BNL join)
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 821.837037
Last_query_cost 1371.437037
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c12 = t2.c21 and t2.c22 = t3.c31 and t3.c32 = t4.c41 and t4.c42 = t5.c51 and t5.c52 = t6.c61 and t6.c62 = t7.c71;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 3
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where
1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t2.c22 1
1 SIMPLE t4 ALL NULL NULL NULL NULL 12 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t5 eq_ref PRIMARY PRIMARY 4 test.t4.c42 1
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t7 eq_ref PRIMARY PRIMARY 4 test.t6.c62 1 Using index
1 SIMPLE t1 ALL NULL NULL NULL NULL 3 Using where; Using join buffer (flat, BNL join)
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 821.837037
Last_query_cost 1371.437037
explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where
@@ -231,11 +231,11 @@ id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 eq_ref PRIMARY PRIMARY 4 test.t2.c21 1 Using where
1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t1.c12 1 Using index
1 SIMPLE t5 eq_ref PRIMARY PRIMARY 4 test.t1.c14 1 Using index
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t7 eq_ref PRIMARY PRIMARY 4 test.t1.c16 1 Using index
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 289.418727
Last_query_cost 362.618727
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where
@@ -243,11 +243,11 @@ id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 eq_ref PRIMARY PRIMARY 4 test.t2.c21 1 Using where
1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t1.c12 1 Using index
1 SIMPLE t5 eq_ref PRIMARY PRIMARY 4 test.t1.c14 1 Using index
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t7 eq_ref PRIMARY PRIMARY 4 test.t1.c16 1 Using index
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 289.418727
Last_query_cost 362.618727
explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71 and t2.c22 = t3.c32 and t2.c23 = t4.c42 and t2.c24 = t5.c52 and t2.c25 = t6.c62 and t2.c26 = t7.c72 and t3.c33 = t4.c43 and t3.c34 = t5.c53 and t3.c35 = t6.c63 and t3.c36 = t7.c73 and t4.c42 = t5.c54 and t4.c43 = t6.c64 and t4.c44 = t7.c74 and t5.c52 = t6.c65 and t5.c53 = t7.c75 and t6.c62 = t7.c76;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where
@@ -255,11 +255,11 @@ id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 eq_ref PRIMARY PRIMARY 4 test.t2.c21 1 Using where
1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t1.c12 1 Using where
1 SIMPLE t5 eq_ref PRIMARY PRIMARY 4 test.t1.c14 1 Using where
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t7 eq_ref PRIMARY PRIMARY 4 test.t1.c16 1 Using where
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 289.418727
Last_query_cost 362.618727
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71 and t2.c22 = t3.c32 and t2.c23 = t4.c42 and t2.c24 = t5.c52 and t2.c25 = t6.c62 and t2.c26 = t7.c72 and t3.c33 = t4.c43 and t3.c34 = t5.c53 and t3.c35 = t6.c63 and t3.c36 = t7.c73 and t4.c42 = t5.c54 and t4.c43 = t6.c64 and t4.c44 = t7.c74 and t5.c52 = t6.c65 and t5.c53 = t7.c75 and t6.c62 = t7.c76;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where
@@ -267,11 +267,11 @@ id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 eq_ref PRIMARY PRIMARY 4 test.t2.c21 1 Using where
1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t1.c12 1 Using where
1 SIMPLE t5 eq_ref PRIMARY PRIMARY 4 test.t1.c14 1 Using where
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t7 eq_ref PRIMARY PRIMARY 4 test.t1.c16 1 Using where
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 289.418727
Last_query_cost 362.618727
set optimizer_search_depth=1;
select @@optimizer_search_depth;
@@optimizer_search_depth
@@ -287,7 +287,7 @@ id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t7 eq_ref PRIMARY PRIMARY 4 test.t6.c62 1 Using index
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 821.837037
Last_query_cost 1693.637037
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c12 = t2.c21 and t2.c22 = t3.c31 and t3.c32 = t4.c41 and t4.c42 = t5.c51 and t5.c52 = t6.c61 and t6.c62 = t7.c71;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 3
@@ -299,7 +299,7 @@ id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t7 eq_ref PRIMARY PRIMARY 4 test.t6.c62 1 Using index
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 821.837037
Last_query_cost 1693.637037
explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL PRIMARY NULL NULL NULL 3 Using where
@@ -311,7 +311,7 @@ id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 794.837037
Last_query_cost 844.037037
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL PRIMARY NULL NULL NULL 3 Using where
@@ -323,7 +323,7 @@ id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 794.837037
Last_query_cost 844.037037
explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71 and t2.c22 = t3.c32 and t2.c23 = t4.c42 and t2.c24 = t5.c52 and t2.c25 = t6.c62 and t2.c26 = t7.c72 and t3.c33 = t4.c43 and t3.c34 = t5.c53 and t3.c35 = t6.c63 and t3.c36 = t7.c73 and t4.c42 = t5.c54 and t4.c43 = t6.c64 and t4.c44 = t7.c74 and t5.c52 = t6.c65 and t5.c53 = t7.c75 and t6.c62 = t7.c76;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL PRIMARY NULL NULL NULL 3 Using where
@@ -335,7 +335,7 @@ id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 794.837037
Last_query_cost 844.037037
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71 and t2.c22 = t3.c32 and t2.c23 = t4.c42 and t2.c24 = t5.c52 and t2.c25 = t6.c62 and t2.c26 = t7.c72 and t3.c33 = t4.c43 and t3.c34 = t5.c53 and t3.c35 = t6.c63 and t3.c36 = t7.c73 and t4.c42 = t5.c54 and t4.c43 = t6.c64 and t4.c44 = t7.c74 and t5.c52 = t6.c65 and t5.c53 = t7.c75 and t6.c62 = t7.c76;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL PRIMARY NULL NULL NULL 3 Using where
@@ -347,35 +347,35 @@ id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 794.837037
Last_query_cost 844.037037
set optimizer_search_depth=62;
select @@optimizer_search_depth;
@@optimizer_search_depth
62
explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c12 = t2.c21 and t2.c22 = t3.c31 and t3.c32 = t4.c41 and t4.c42 = t5.c51 and t5.c52 = t6.c61 and t6.c62 = t7.c71;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 3
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where
1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t2.c22 1
1 SIMPLE t4 ALL NULL NULL NULL NULL 12 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t5 eq_ref PRIMARY PRIMARY 4 test.t4.c42 1
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t7 eq_ref PRIMARY PRIMARY 4 test.t6.c62 1 Using index
1 SIMPLE t1 ALL NULL NULL NULL NULL 3 Using where; Using join buffer (flat, BNL join)
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 821.837037
Last_query_cost 1371.437037
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c12 = t2.c21 and t2.c22 = t3.c31 and t3.c32 = t4.c41 and t4.c42 = t5.c51 and t5.c52 = t6.c61 and t6.c62 = t7.c71;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 3
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where
1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t2.c22 1
1 SIMPLE t4 ALL NULL NULL NULL NULL 12 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t5 eq_ref PRIMARY PRIMARY 4 test.t4.c42 1
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t7 eq_ref PRIMARY PRIMARY 4 test.t6.c62 1 Using index
1 SIMPLE t1 ALL NULL NULL NULL NULL 3 Using where; Using join buffer (flat, BNL join)
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 821.837037
Last_query_cost 1371.437037
explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where
@@ -383,11 +383,11 @@ id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 eq_ref PRIMARY PRIMARY 4 test.t2.c21 1 Using where
1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t1.c12 1 Using index
1 SIMPLE t5 eq_ref PRIMARY PRIMARY 4 test.t1.c14 1 Using index
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t7 eq_ref PRIMARY PRIMARY 4 test.t1.c16 1 Using index
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 289.418727
Last_query_cost 362.618727
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where
@@ -395,11 +395,11 @@ id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 eq_ref PRIMARY PRIMARY 4 test.t2.c21 1 Using where
1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t1.c12 1 Using index
1 SIMPLE t5 eq_ref PRIMARY PRIMARY 4 test.t1.c14 1 Using index
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t7 eq_ref PRIMARY PRIMARY 4 test.t1.c16 1 Using index
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 289.418727
Last_query_cost 362.618727
explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71 and t2.c22 = t3.c32 and t2.c23 = t4.c42 and t2.c24 = t5.c52 and t2.c25 = t6.c62 and t2.c26 = t7.c72 and t3.c33 = t4.c43 and t3.c34 = t5.c53 and t3.c35 = t6.c63 and t3.c36 = t7.c73 and t4.c42 = t5.c54 and t4.c43 = t6.c64 and t4.c44 = t7.c74 and t5.c52 = t6.c65 and t5.c53 = t7.c75 and t6.c62 = t7.c76;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where
@@ -407,11 +407,11 @@ id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 eq_ref PRIMARY PRIMARY 4 test.t2.c21 1 Using where
1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t1.c12 1 Using where
1 SIMPLE t5 eq_ref PRIMARY PRIMARY 4 test.t1.c14 1 Using where
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t7 eq_ref PRIMARY PRIMARY 4 test.t1.c16 1 Using where
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 289.418727
Last_query_cost 362.618727
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71 and t2.c22 = t3.c32 and t2.c23 = t4.c42 and t2.c24 = t5.c52 and t2.c25 = t6.c62 and t2.c26 = t7.c72 and t3.c33 = t4.c43 and t3.c34 = t5.c53 and t3.c35 = t6.c63 and t3.c36 = t7.c73 and t4.c42 = t5.c54 and t4.c43 = t6.c64 and t4.c44 = t7.c74 and t5.c52 = t6.c65 and t5.c53 = t7.c75 and t6.c62 = t7.c76;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where
@@ -419,11 +419,11 @@ id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 eq_ref PRIMARY PRIMARY 4 test.t2.c21 1 Using where
1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t1.c12 1 Using where
1 SIMPLE t5 eq_ref PRIMARY PRIMARY 4 test.t1.c14 1 Using where
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t7 eq_ref PRIMARY PRIMARY 4 test.t1.c16 1 Using where
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 289.418727
Last_query_cost 362.618727
set optimizer_prune_level=1;
select @@optimizer_prune_level;
@@optimizer_prune_level
@@ -443,7 +443,7 @@ id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t7 eq_ref PRIMARY PRIMARY 4 test.t6.c62 1 Using index
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 821.837037
Last_query_cost 1693.637037
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c12 = t2.c21 and t2.c22 = t3.c31 and t3.c32 = t4.c41 and t4.c42 = t5.c51 and t5.c52 = t6.c61 and t6.c62 = t7.c71;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 3
@@ -455,55 +455,55 @@ id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t7 eq_ref PRIMARY PRIMARY 4 test.t6.c62 1 Using index
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 821.837037
Last_query_cost 1693.637037
explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL PRIMARY NULL NULL NULL 3 Using where
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t1.c12 1 Using index
1 SIMPLE t4 ALL NULL NULL NULL NULL 12 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t5 eq_ref PRIMARY PRIMARY 4 test.t1.c14 1 Using index
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t7 eq_ref PRIMARY PRIMARY 4 test.t1.c16 1 Using index
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t4 ALL NULL NULL NULL NULL 12 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 794.837037
Last_query_cost 844.037037
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL PRIMARY NULL NULL NULL 3 Using where
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t1.c12 1 Using index
1 SIMPLE t4 ALL NULL NULL NULL NULL 12 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t5 eq_ref PRIMARY PRIMARY 4 test.t1.c14 1 Using index
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t7 eq_ref PRIMARY PRIMARY 4 test.t1.c16 1 Using index
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t4 ALL NULL NULL NULL NULL 12 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 794.837037
Last_query_cost 844.037037
explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71 and t2.c22 = t3.c32 and t2.c23 = t4.c42 and t2.c24 = t5.c52 and t2.c25 = t6.c62 and t2.c26 = t7.c72 and t3.c33 = t4.c43 and t3.c34 = t5.c53 and t3.c35 = t6.c63 and t3.c36 = t7.c73 and t4.c42 = t5.c54 and t4.c43 = t6.c64 and t4.c44 = t7.c74 and t5.c52 = t6.c65 and t5.c53 = t7.c75 and t6.c62 = t7.c76;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL PRIMARY NULL NULL NULL 3 Using where
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t1.c12 1 Using where
1 SIMPLE t4 ALL NULL NULL NULL NULL 12 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t1.c12 1
1 SIMPLE t5 eq_ref PRIMARY PRIMARY 4 test.t1.c14 1 Using where
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t7 eq_ref PRIMARY PRIMARY 4 test.t1.c16 1 Using where
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t4 ALL NULL NULL NULL NULL 12 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 794.837037
Last_query_cost 844.037037
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71 and t2.c22 = t3.c32 and t2.c23 = t4.c42 and t2.c24 = t5.c52 and t2.c25 = t6.c62 and t2.c26 = t7.c72 and t3.c33 = t4.c43 and t3.c34 = t5.c53 and t3.c35 = t6.c63 and t3.c36 = t7.c73 and t4.c42 = t5.c54 and t4.c43 = t6.c64 and t4.c44 = t7.c74 and t5.c52 = t6.c65 and t5.c53 = t7.c75 and t6.c62 = t7.c76;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL PRIMARY NULL NULL NULL 3 Using where
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t1.c12 1 Using where
1 SIMPLE t4 ALL NULL NULL NULL NULL 12 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t1.c12 1
1 SIMPLE t5 eq_ref PRIMARY PRIMARY 4 test.t1.c14 1 Using where
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t7 eq_ref PRIMARY PRIMARY 4 test.t1.c16 1 Using where
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t4 ALL NULL NULL NULL NULL 12 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 794.837037
Last_query_cost 844.037037
set optimizer_search_depth=1;
select @@optimizer_search_depth;
@@optimizer_search_depth
@@ -519,7 +519,7 @@ id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t7 eq_ref PRIMARY PRIMARY 4 test.t6.c62 1 Using index
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 821.837037
Last_query_cost 1693.637037
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c12 = t2.c21 and t2.c22 = t3.c31 and t3.c32 = t4.c41 and t4.c42 = t5.c51 and t5.c52 = t6.c61 and t6.c62 = t7.c71;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 3
@@ -531,7 +531,7 @@ id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t7 eq_ref PRIMARY PRIMARY 4 test.t6.c62 1 Using index
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 821.837037
Last_query_cost 1693.637037
explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL PRIMARY NULL NULL NULL 3 Using where
@@ -543,7 +543,7 @@ id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 794.837037
Last_query_cost 844.037037
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL PRIMARY NULL NULL NULL 3 Using where
@@ -555,7 +555,7 @@ id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 794.837037
Last_query_cost 844.037037
explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71 and t2.c22 = t3.c32 and t2.c23 = t4.c42 and t2.c24 = t5.c52 and t2.c25 = t6.c62 and t2.c26 = t7.c72 and t3.c33 = t4.c43 and t3.c34 = t5.c53 and t3.c35 = t6.c63 and t3.c36 = t7.c73 and t4.c42 = t5.c54 and t4.c43 = t6.c64 and t4.c44 = t7.c74 and t5.c52 = t6.c65 and t5.c53 = t7.c75 and t6.c62 = t7.c76;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL PRIMARY NULL NULL NULL 3 Using where
@@ -567,7 +567,7 @@ id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 794.837037
Last_query_cost 844.037037
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71 and t2.c22 = t3.c32 and t2.c23 = t4.c42 and t2.c24 = t5.c52 and t2.c25 = t6.c62 and t2.c26 = t7.c72 and t3.c33 = t4.c43 and t3.c34 = t5.c53 and t3.c35 = t6.c63 and t3.c36 = t7.c73 and t4.c42 = t5.c54 and t4.c43 = t6.c64 and t4.c44 = t7.c74 and t5.c52 = t6.c65 and t5.c53 = t7.c75 and t6.c62 = t7.c76;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL PRIMARY NULL NULL NULL 3 Using where
@@ -579,7 +579,7 @@ id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 794.837037
Last_query_cost 844.037037
set optimizer_search_depth=62;
select @@optimizer_search_depth;
@@optimizer_search_depth
@@ -595,7 +595,7 @@ id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t7 eq_ref PRIMARY PRIMARY 4 test.t6.c62 1 Using index
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 821.837037
Last_query_cost 1693.637037
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c12 = t2.c21 and t2.c22 = t3.c31 and t3.c32 = t4.c41 and t4.c42 = t5.c51 and t5.c52 = t6.c61 and t6.c62 = t7.c71;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 3
@@ -607,55 +607,55 @@ id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t7 eq_ref PRIMARY PRIMARY 4 test.t6.c62 1 Using index
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 821.837037
Last_query_cost 1693.637037
explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL PRIMARY NULL NULL NULL 3 Using where
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t1.c12 1 Using index
1 SIMPLE t4 ALL NULL NULL NULL NULL 12 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t5 eq_ref PRIMARY PRIMARY 4 test.t1.c14 1 Using index
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t7 eq_ref PRIMARY PRIMARY 4 test.t1.c16 1 Using index
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t4 ALL NULL NULL NULL NULL 12 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 794.837037
Last_query_cost 844.037037
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL PRIMARY NULL NULL NULL 3 Using where
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t1.c12 1 Using index
1 SIMPLE t4 ALL NULL NULL NULL NULL 12 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t5 eq_ref PRIMARY PRIMARY 4 test.t1.c14 1 Using index
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t7 eq_ref PRIMARY PRIMARY 4 test.t1.c16 1 Using index
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t4 ALL NULL NULL NULL NULL 12 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 794.837037
Last_query_cost 844.037037
explain select t1.c11 from t1, t2, t3, t4, t5, t6, t7 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71 and t2.c22 = t3.c32 and t2.c23 = t4.c42 and t2.c24 = t5.c52 and t2.c25 = t6.c62 and t2.c26 = t7.c72 and t3.c33 = t4.c43 and t3.c34 = t5.c53 and t3.c35 = t6.c63 and t3.c36 = t7.c73 and t4.c42 = t5.c54 and t4.c43 = t6.c64 and t4.c44 = t7.c74 and t5.c52 = t6.c65 and t5.c53 = t7.c75 and t6.c62 = t7.c76;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL PRIMARY NULL NULL NULL 3 Using where
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t1.c12 1 Using where
1 SIMPLE t4 ALL NULL NULL NULL NULL 12 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t1.c12 1
1 SIMPLE t5 eq_ref PRIMARY PRIMARY 4 test.t1.c14 1 Using where
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t7 eq_ref PRIMARY PRIMARY 4 test.t1.c16 1 Using where
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t4 ALL NULL NULL NULL NULL 12 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 794.837037
Last_query_cost 844.037037
explain select t1.c11 from t7, t6, t5, t4, t3, t2, t1 where t1.c11 = t2.c21 and t1.c12 = t3.c31 and t1.c13 = t4.c41 and t1.c14 = t5.c51 and t1.c15 = t6.c61 and t1.c16 = t7.c71 and t2.c22 = t3.c32 and t2.c23 = t4.c42 and t2.c24 = t5.c52 and t2.c25 = t6.c62 and t2.c26 = t7.c72 and t3.c33 = t4.c43 and t3.c34 = t5.c53 and t3.c35 = t6.c63 and t3.c36 = t7.c73 and t4.c42 = t5.c54 and t4.c43 = t6.c64 and t4.c44 = t7.c74 and t5.c52 = t6.c65 and t5.c53 = t7.c75 and t6.c62 = t7.c76;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL PRIMARY NULL NULL NULL 3 Using where
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t1.c12 1 Using where
1 SIMPLE t4 ALL NULL NULL NULL NULL 12 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t3 eq_ref PRIMARY PRIMARY 4 test.t1.c12 1
1 SIMPLE t5 eq_ref PRIMARY PRIMARY 4 test.t1.c14 1 Using where
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t7 eq_ref PRIMARY PRIMARY 4 test.t1.c16 1 Using where
1 SIMPLE t2 ALL NULL NULL NULL NULL 6 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t4 ALL NULL NULL NULL NULL 12 Using where; Using join buffer (flat, BNL join)
1 SIMPLE t6 ALL NULL NULL NULL NULL 18 Using where; Using join buffer (flat, BNL join)
show status like 'Last_query_cost';
Variable_name Value
Last_query_cost 794.837037
Last_query_cost 844.037037
drop table t1,t2,t3,t4,t5,t6,t7;
CREATE TABLE t1 (a int, b int, d int, i int);
INSERT INTO t1 VALUES (1,1,1,1);