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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)
37 lines
1.3 KiB
Text
37 lines
1.3 KiB
Text
DESC sys.schema_redundant_indexes;
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Field Type Null Key Default Extra
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table_schema varchar(64) NO NULL
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table_name varchar(64) NO NULL
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redundant_index_name varchar(64) NO NULL
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redundant_index_columns mediumtext YES NULL
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redundant_index_non_unique bigint(1) YES NULL
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dominant_index_name varchar(64) NO NULL
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dominant_index_columns mediumtext YES NULL
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dominant_index_non_unique bigint(1) YES NULL
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subpart_exists int(1) YES NULL
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sql_drop_index varchar(223) YES NULL
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SELECT * FROM sys.schema_redundant_indexes;
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DESC sys.x$schema_flattened_keys;
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Field Type Null Key Default Extra
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table_schema varchar(64) NO NULL
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table_name varchar(64) NO NULL
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index_name varchar(64) NO NULL
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non_unique bigint(1) YES NULL
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subpart_exists bigint(1) YES NULL
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index_columns mediumtext YES NULL
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SELECT * FROM sys.x$schema_flattened_keys;
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CREATE DATABASE rkey;
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CREATE TABLE rkey.rkey (
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i INT,
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j INT,
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k INT,
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PRIMARY KEY (i),
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KEY (j),
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KEY (j, k),
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KEY (i, j, k)
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);
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SELECT * FROM sys.schema_redundant_indexes;
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table_schema table_name redundant_index_name redundant_index_columns redundant_index_non_unique dominant_index_name dominant_index_columns dominant_index_non_unique subpart_exists sql_drop_index
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rkey rkey i i,j,k 1 PRIMARY i 0 0 ALTER TABLE `rkey`.`rkey` DROP INDEX `i`
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rkey rkey j j 1 j_2 j,k 1 0 ALTER TABLE `rkey`.`rkey` DROP INDEX `j`
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DROP DATABASE rkey;
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