ID,Entered,Modified,Type,Status,Severity,Version,OS,Summary
26232,2007-02-09 17:28:20,2007-02-15 18:36:58,Server: Optimizer,Verified,S3,"4.1.22, 5.0.34, 5.0.36-BK","Linux (Linux)","review of  bug #20944 / proof of concept attached"
29443,2007-06-29 13:28:44,2010-10-14 12:30:03,Server: Optimizer,Verified,S3,"5.1.19","Any","cost calculations are off"
42948,2009-02-17 23:02:39,2009-03-03 18:56:38,Server: Optimizer,Verified,S5,"5.0.67-0ubuntu6, 6.0.11","Linux (Ubuntu 8.10)","MySQL Optimizer does not properly use Indexes on Views with ""Group By"""
44549,2009-04-29 17:47:30,2026-06-10 21:36:47,Server: Optimizer,Verified,S3,"5.0.80, 5.1.34","Any","optimizer incorrectly chooses table scan and filesort over index "
44201,2009-04-10 03:04:52,2010-06-15 19:10:38,Server: Optimizer,Verified,S3,"5.1.32, 5.1.35-bzr, 6.0.11-bzr, 5.0, 5.6.99","Any","Performance problem with View"
46376,2009-07-24 17:05:25,2009-07-29 08:39:23,Server: Optimizer,Verified,S5,"5.0.85, 5.1.36, 5.1.38, 5.1.39","Windows (XP)","Optimizer choose wrong index even when where clause and order-by are covered"
48049,2009-10-14 16:46:51,2026-06-10 21:36:47,Server: Optimizer,Verified,S3,"5.1.37, 5.5.7","Any","SELECT MIN(1)  reports differently for MERGE tables in 5.0 and 5.1"
47454,2009-09-19 19:33:40,2009-09-20 07:24:58,Server: Optimizer,Verified,S3,"5.1.35","Any","Not exists optimization method is not used for NULL columns in the right table"
58101,2010-11-10 00:21:44,2010-11-11 09:50:17,Server: Optimizer,Verified,S5,"5.1.38-community-log, 5.1.54-bzr","Linux","Optimizer picks wrong order of queries"
67351,2012-10-24 08:02:07,2012-12-01 16:00:46,Server: Partition,In progress,S2,"5.5.27-29.0","Linux","Cardinality samples of partitioned tables sometimes widely off"
68554,2013-03-03 16:16:08,2013-03-18 12:42:23,Server: Optimizer,Verified,S5,"5.6.10","Any","Optimizer wrongly choses covering index over  ICP"
71191,2013-12-20 15:30:25,2013-12-20 20:19:51,Server: Optimizer,Verified,S3,"5.5.33","Any","Loose index scan is used even though full table scan/tight index scan is faster"
71199,2013-12-21 18:16:34,2013-12-23 07:33:28,Server: Optimizer,Verified,S3,"5.6.14, 5.6.15, 5.5.35","Any","Optimizer's estimated number of rows is 2 times wrong for (loose?) index scans"
71189,2013-12-20 14:56:53,2013-12-20 20:02:38,Server: Docs,Verified,S3,"5.5, any","Any","Manual does not provide enough details on how loose index scan really works"
74049,2014-09-24 08:01:47,2014-09-24 09:59:52,Server: Optimizer,Verified,S3,"5.6.19-67.0, 5.6.22","Any","Update query use filesort instead of index"
74083,2014-09-25 18:11:12,2014-10-09 12:52:59,Server: Optimizer,Verified,S5,"5.6.20, 5.6.22","Linux (CentOS 6.5)","ENUM index scan is slower than INT index scan"
80067,2016-01-20 10:50:43,2016-01-20 11:39:02,Server: Optimizer,Verified,S3,"5.6.28, 5.7.10","Any","Index on BIT column is NOT used when column name only is used in WHERE clause"
30342,2007-08-09 18:52:04,2015-10-07 14:54:53,Server: Optimizer,Verified,S5,"5.0.37, 5.6.17","Any","Equality propagation can make optimization much slower"
83062,2016-09-20 13:18:22,2016-09-21 08:13:44,Server: Optimizer,Verified,S3,"5.6.32, 5.7.14, 5.6.33, 5.7.15","Any","it's no longer possible to determine used key parts by looking at key_length"
83071,2016-09-21 08:02:40,2016-09-21 08:33:23,Server: Optimizer,Verified,S3,"5.7.14, 5.6.*, 5.7.15","Any","MySQL prefers first declared index over more useful other indexes"
83248,2016-10-03 15:57:04,2016-10-03 17:12:40,Server: Optimizer,Verified,S3,"8.0.0, 5.7.15","Any","Partition pruning is not working with LEFT JOIN"
83323,2016-10-10 18:02:33,2017-04-24 21:32:03,Server: Optimizer,Verified,S3,"5.7, 5.6, 8.0.1","Any","Optimizer chooses wrong plan when joining 2 tables"
86036,2017-04-21 10:08:42,2017-04-23 00:52:21,Server: InnoDB,Verified,S3,"5.7/8.0","Any","InnoDB FULLTEXT index has too strict innodb_ft_result_cache_limit max limit"
93360,2018-11-27 09:41:47,2018-12-12 14:45:01,Server: Optimizer,Verified,S5,"5.6.16,5.7.23","Linux","mysterious optimizer behavior"
100885,2020-09-18 03:43:07,2020-09-18 07:28:47,Server: JSON,Verified,S5,"5.7.31","Any","generated column index against json column is not used with different encoding"
104978,2021-09-17 19:57:07,2021-09-20 08:58:51,Server: Optimizer,Verified,S5,"8.0.26, 5.7.35","Windows","Adding Join Index forces query optimizer to use inefficient execution plan"
106473,2022-02-16 08:55:54,2022-03-10 09:27:49,Server: Optimizer,Verified,S3,"8.0.28","Any","Inner table of OUT-JOIN is nullable, after applying OUTER2INNER transformation"
99684,2020-05-25 12:19:09,2020-05-28 13:22:02,Server: Optimizer,Verified,S3,"5.6, 5.7, 8.0","Any","incorrect determination of big test"
108127,2022-08-12 05:57:25,2022-08-16 12:36:02,Server: Optimizer,Verified,S5,"8.0.29","Any","MySQL optimizer chooses to a inefficient index ."
110117,2023-02-17 13:22:59,2023-02-17 14:01:31,Server: Docs,Verified,S3,"8.0","Any","Lack of instrumentation for index condition impact on the query plan"
110111,2023-02-17 12:53:41,2023-02-20 12:30:07,Server: Optimizer,Verified,S5,"8.0.31","Any","Optimizer chooses worst plan when index condition pushdown opportunity"
110848,2023-04-27 15:04:26,2023-05-03 09:56:46,Server: Optimizer,Verified,S5,"8.0.28, 8.0.33","Any","missing considering on order by and limit clause in cost calculation"
111431,2023-06-15 08:47:57,2023-06-15 09:16:40,Server: Optimizer,Verified,S3,"8.0.33","Ubuntu (22.04)","condition_fanout_filter optimizer wrong result?"
112902,2023-10-31 14:39:48,2024-02-26 09:39:10,Server: Optimizer,Verified,S5,"8.0.31, 8.0.35","Linux (n.a.)","Optimizer in MySQL 8 is significantly slower on dependent subqueries than 5.7"
115815,2024-08-12 02:56:14,2024-08-12 07:57:26,Server: Optimizer,Verified,S2,"8.4.2","Any","Contribute by tencent: EXPLAIN FORMAT=TREE Incorrectly Shows Cost of Statement"
116335,2024-10-10 16:53:47,2024-10-11 08:03:41,Server: Optimizer,Verified,S5,"8.0.39","Any","Multi-valued index isn't used with some range scans on composite indexes"
116710,2024-11-19 12:47:24,2024-11-20 02:55:01,Server: Optimizer,Verified,S3,"8.0","Any","explain shows wrong cost value"
116937,2024-12-11 08:25:08,2024-12-11 15:30:30,Server: Optimizer,Verified,S3,"8.0, 8.0.40","Any","estimation of REF is modified by index diving of INDEX MERGE"
117164,2025-01-09 06:17:45,2025-01-09 07:04:21,Server: Optimizer,Verified,S3,"8.0.36, 8.0.40","Any","Range estimation (index dives) overestimates the rows count on large ranges. It almost doubles the actual number of rows"
119442,2025-11-21 20:13:10,2025-11-27 04:52:54,Server: Optimizer,Patch pending,S5,"8.4.4","Any","Optimizer fails to simplify ORDER BY when column is filtered by IS NULL, causing filesort"
119447,2025-11-23 08:34:44,2025-11-27 05:04:39,Server: Optimizer,Verified,S5,"8.0.41","CentOS","Prepare Statement execute much slower than normal select query"
120031,2026-03-11 14:48:13,2026-03-11 20:46:07,Server: Optimizer,Verified,S3,"8.4.8","Any","Inconsistent INTERSECT Results in Derived Tables: Impact of PRIMARY KEY on JSON_OBJECTAGG and LEAST Operators"
120036,2026-03-12 02:09:29,2026-03-13 13:14:40,Server: Optimizer,Verified,S3,"8.0.45","Any","Different results for semantically equivalent expressions using CASE and MIN(CASE ...) with GROUP BY on a FLOAT column"
120142,2026-03-25 03:09:27,2026-03-25 19:06:55,Server: JSON,Verified,S3,"8.0.45","Any","Incorrect result with DISTINCTROW and JSON_OBJECTAGG when replacing COALESCE(SUM(NULL),0) with constant"
120574,2026-05-29 14:05:16,2026-06-10 21:36:47,Server: Optimizer,Open,S2,"8.0.41","Any","Range optimizer exceeds memory limit and chooses bad range plan for large IN lists"
120575,2026-05-30 06:57:19,2026-06-10 21:36:47,Server: Optimizer,Open,S2,"8.0.41+","Any","Range optimizer chooses bad range plan for large IN lists and execution is very slow and memory usage spikes."