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727491b72a
This includes all test changes from
"Changing all cost calculation to be given in milliseconds"
and forwards.
Some of the things that caused changes in the result files:
- As part of fixing tests, I added 'echo' to some comments to be able to
easier find out where things where wrong.
- MATERIALIZED has now a higher cost compared to X than before. Because
of this some MATERIALIZED types have changed to DEPENDEND SUBQUERY.
- Some test cases that required MATERIALIZED to repeat a bug was
changed by adding more rows to force MATERIALIZED to happen.
- 'Filtered' in SHOW EXPLAIN has in many case changed from 100.00 to
something smaller. This is because now filtered also takes into
account the smallest possible ref access and filters, even if they
where not used. Another reason for 'Filtered' being smaller is that
we now also take into account implicit filtering done for subqueries
using FIRSTMATCH.
(main.subselect_no_exists_to_in)
This is caluculated in best_access_path() and stored in records_out.
- Table orders has changed because more accurate costs.
- 'index' and 'ALL' for small tables has changed to use 'range' or
'ref' because of optimizer_scan_setup_cost.
- index can be changed to 'range' as 'range' optimizer assumes we don't
have to read the blocks from disk that range optimizer has already read.
This can be confusing in the case where there is no obvious where clause
but instead there is a hidden 'key_column > NULL' added by the optimizer.
(main.subselect_no_exists_to_in)
- Scan on primary clustered key does not report 'Using Index' anymore
(It's a table scan, not an index scan).
- For derived tables, the number of rows is now 100 instead of 2,
which can be seen in EXPLAIN.
- More tests have "Using index for group by" as the cost of this
optimization is now more correct (lower).
- A primary key could be preferred for a normal key, even if it would
access more rows, as it's faster to do 1 lokoup and 3 'index_next' on a
clustered primary key than one lookup trough a secondary.
(main.stat_tables_innodb)
Notes:
- There was a 4.7% more calls to best_extension_by_limited_search() in
the main.greedy_optimizer test. However examining the test results
it looked that the plans where slightly better (eq_ref where more
chained together) so I assume this is ok.
- I have verified a few test cases where there was notable/unexpected
changes in the plan and in all cases the new optimizer plans where
faster. (main.greedy_optimizer and some others)
97 lines
4.3 KiB
Text
97 lines
4.3 KiB
Text
drop table if exists t1;
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SET SQL_SAFE_UPDATES=1,SQL_SELECT_LIMIT=4, MAX_JOIN_SIZE=9;
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create table t1 (a int auto_increment primary key, b char(20));
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insert into t1 values(1,"test");
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SELECT SQL_BUFFER_RESULT * from t1;
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a b
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1 test
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update t1 set b="a" where a=1;
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delete from t1 where a=1;
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insert into t1 values(1,"test"),(2,"test2");
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SELECT SQL_BUFFER_RESULT * from t1;
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a b
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1 test
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2 test2
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update t1 set b="a" where a=1;
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select 1 from t1,t1 as t2,t1 as t3;
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1
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1
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1
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1
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1
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update t1 set b="a";
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ERROR HY000: You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
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update t1 set b="a" where b="test";
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ERROR HY000: You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
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delete from t1;
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ERROR HY000: You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
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delete from t1 where b="test";
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ERROR HY000: You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
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delete from t1 where a+0=1;
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ERROR HY000: You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
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select 1 from t1,t1 as t2,t1 as t3,t1 as t4,t1 as t5;
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ERROR 42000: The SELECT would examine more than MAX_JOIN_SIZE rows; check your WHERE and use SET SQL_BIG_SELECTS=1 or SET MAX_JOIN_SIZE=# if the SELECT is okay
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update t1 set b="a" limit 1;
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update t1 set b="a" where b="b" limit 2;
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delete from t1 where b="test" limit 1;
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delete from t1 where a+0=1 limit 2;
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alter table t1 add key b (b);
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SET MAX_JOIN_SIZE=2;
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SELECT @@MAX_JOIN_SIZE, @@SQL_BIG_SELECTS;
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@@MAX_JOIN_SIZE @@SQL_BIG_SELECTS
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2 0
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insert into t1 values (null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a");
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SELECT * from t1 order by a;
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ERROR 42000: The SELECT would examine more than MAX_JOIN_SIZE rows; check your WHERE and use SET SQL_BIG_SELECTS=1 or SET MAX_JOIN_SIZE=# if the SELECT is okay
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SET SQL_BIG_SELECTS=1;
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SELECT * from t1 order by a;
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a b
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2 test2
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3 a
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4 a
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5 a
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SET MAX_JOIN_SIZE=2;
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SELECT * from t1;
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ERROR 42000: The SELECT would examine more than MAX_JOIN_SIZE rows; check your WHERE and use SET SQL_BIG_SELECTS=1 or SET MAX_JOIN_SIZE=# if the SELECT is okay
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SET MAX_JOIN_SIZE=DEFAULT;
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SELECT * from t1;
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a b
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2 test2
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3 a
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4 a
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5 a
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analyze table t1;
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Table Op Msg_type Msg_text
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test.t1 analyze status Engine-independent statistics collected
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test.t1 analyze status OK
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insert into t1 values (null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a");
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insert into t1 values (null,"b"),(null,"b"),(null,"c"),(null,"c"),(null,"d"),(null,"d"),(null,"e"),(null,"e"),(null,"a"),(null,"e");
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insert into t1 values (null,"x"),(null,"x"),(null,"y"),(null,"y"),(null,"z"),(null,"z"),(null,"v"),(null,"v"),(null,"a"),(null,"v");
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set @@optimizer_where_cost=0.3;
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explain select STRAIGHT_JOIN * from t1,t1 as t2 where t1.b=t2.b;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 ALL b NULL NULL NULL 11
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1 SIMPLE t2 ALL b NULL NULL NULL 11 Using where; Using join buffer (flat, BNL join)
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set MAX_SEEKS_FOR_KEY=1;
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explain select STRAIGHT_JOIN * from t1,t1 as t2 where t1.b=t2.b;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 ALL b NULL NULL NULL 11
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1 SIMPLE t2 ALL b NULL NULL NULL 11 Using where; Using join buffer (flat, BNL join)
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SET MAX_SEEKS_FOR_KEY=DEFAULT;
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drop table t1;
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create table t1 (a int);
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insert into t1 values (1),(2),(3),(4),(5);
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insert into t1 select * from t1;
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insert into t1 select * from t1;
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insert into t1 select * from t1;
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set local max_join_size=8;
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select * from (select * from t1) x;
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ERROR 42000: The SELECT would examine more than MAX_JOIN_SIZE rows; check your WHERE and use SET SQL_BIG_SELECTS=1 or SET MAX_JOIN_SIZE=# if the SELECT is okay
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set local max_join_size=1;
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select * from (select a.a as aa, b.a as ba from t1 a, t1 b) x;
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ERROR 42000: The SELECT would examine more than MAX_JOIN_SIZE rows; check your WHERE and use SET SQL_BIG_SELECTS=1 or SET MAX_JOIN_SIZE=# if the SELECT is okay
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set local max_join_size=1;
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select * from (select 1 union select 2 union select 3) x;
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ERROR 42000: The SELECT would examine more than MAX_JOIN_SIZE rows; check your WHERE and use SET SQL_BIG_SELECTS=1 or SET MAX_JOIN_SIZE=# if the SELECT is okay
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drop table t1;
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SET SQL_SAFE_UPDATES=0,SQL_SELECT_LIMIT=DEFAULT, MAX_JOIN_SIZE=DEFAULT;
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