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MDEV-34993, part2: backport optimizer_adjust_secondary_key_costs

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...and make the fix for MDEV-34993 switchable. It is enabled by default
and controlled with @optimizer_adjust_secondary_key_costs=fix_card_multiplier
This commit is contained in:
Sergei Petrunia
2024-09-24 10:23:34 +03:00
parent 8166a5d33d
commit 1cda4726ca
9 changed files with 175 additions and 1 deletions
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54
mysql-test/main/selectivity_innodb_notembedded.result
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@ -280,7 +280,61 @@ JS
}
}
]
# Disable the fix and try the same:
set @@optimizer_adjust_secondary_key_costs='';
explain select * from t1
where
pk in (1,2,3,4,5) and
key1 <= 4;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 range PRIMARY,key1 PRIMARY 4 NULL 5 Using where
drop table t1;
# Shows a high multiplier, without a "note":
select
json_detailed(json_extract(trace,'$**.selectivity_for_indexes')) as JS
from
information_schema.optimizer_trace;
JS
[
[
{
"index_name": "PRIMARY",
"selectivity_from_index": 0.005
},
{
"index_name": "key1",
"selectivity_from_index": 0.399,
"selectivity_multiplier": 90.9091
}
]
]
# Includes 1.79...e308 as cost:
select
json_detailed(json_extract(trace,'$**.best_access_path')) as JS
from
information_schema.optimizer_trace;
JS
[
{
"considered_access_paths":
[
{
"access_type": "range",
"resulting_rows": 181.3636545,
"cost": 1.79769e308,
"chosen": true
}
],
"chosen_access_method":
{
"type": "range",
"records": 181.3636545,
"cost": 1.79769e308,
"uses_join_buffering": false
}
}
]
set optimizer_adjust_secondary_key_costs=default;
#
# Clean up
#