diff options
| author | Igor Babaev <igor@askmonty.org> | 2011-12-24 08:55:10 -0800 |
|---|---|---|
| committer | Igor Babaev <igor@askmonty.org> | 2011-12-24 08:55:10 -0800 |
| commit | 2b1f0b875775b65496e959db7f54f6eb4220400e (patch) | |
| tree | 13c9bd8ec3780974596279996d8215caf21c5225 /mysql-test/r/select.result | |
| parent | 5d9fbc617724ce0bb7f90090596772dbb792139d (diff) | |
| download | mariadb-git-2b1f0b875775b65496e959db7f54f6eb4220400e.tar.gz | |
Back-ported the patch of the mysql-5.6 code line that
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.
Diffstat (limited to 'mysql-test/r/select.result')
| -rw-r--r-- | mysql-test/r/select.result | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/mysql-test/r/select.result b/mysql-test/r/select.result index 29a6bb4bf35..fc0f7283981 100644 --- a/mysql-test/r/select.result +++ b/mysql-test/r/select.result @@ -2199,10 +2199,10 @@ a a select * from (t1 as t2 left join t1 as t3 using (a)) inner join t1 on t1.a>1; a a 1 2 -2 2 -3 2 1 3 +2 2 2 3 +3 2 3 3 select * from t1 inner join (t1 as t2 left join t1 as t3 using (a)) on t1.a>1; a a |