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)
Apply this patch from Percona Server (amended for 10.5):
commit cd7201514fee78aaf7d3eb2b28d2573c76f53b84
Author: Laurynas Biveinis <laurynas.biveinis@gmail.com>
Date: Tue Nov 14 06:34:19 2017 +0200
Fix bug 1704195 / 87065 / TDB-83 (Stop ANALYZE TABLE from flushing table definition cache)
Make ANALYZE TABLE stop flushing affected tables from the table
definition cache, which has the effect of not blocking any subsequent
new queries involving the table if there's a parallel long-running
query:
- new table flag HA_ONLINE_ANALYZE, return it for InnoDB and TokuDB
tables;
- in mysql_admin_table, if we are performing ANALYZE TABLE, and the
table flag is set, do not remove the table from the table
definition cache, do not invalidate query cache;
- in partitioning handler, refresh the query optimizer statistics
after ANALYZE if the underlying handler supports HA_ONLINE_ANALYZE;
- new testcases main.percona_nonflushing_analyze_debug,
parts.percona_nonflushing_abalyze_debug and a supporting debug sync
point.
For TokuDB, this change exposes bug TDB-83 (Index cardinality stats
updated for handler::info(HA_STATUS_CONST), not often enough for
tokudb_cardinality_scale_percent). TokuDB may return different
rec_per_key values depending on dynamic variable
tokudb_cardinality_scale_percent value. The server does not have a way
of knowing that changing this variable invalidates the previous
rec_per_key values in any opened table shares, and so does not call
info(HA_STATUS_CONST) again. Fix by updating rec_per_key for both
HA_STATUS_CONST and HA_STATUS_VARIABLE. This also forces a re-record
of tokudb.bugs.db756_card_part_hash_1_pick, with the new output
seeming to be more correct.