【发布时间】：2021-01-02 00:43:07
【问题描述】：
我有一个我认为是完美的数据库副本。不幸的是，一个特定的查询现在非常慢。这些是 MySQL Workbench 生成的查询分析图像。您可以看到在底部（较慢）连接顺序不同，这似乎是瓶颈。我不知道什么会导致加入顺序发生变化。有人有什么想法吗？
查询：
SELECT
mutation.ENTREZ_GENE_ID AS entrezGeneId,
gene.HUGO_GENE_SYMBOL AS hugoGeneSymbol,
COUNT(*) AS totalCount,
COUNT(DISTINCT (mutation.SAMPLE_ID)) AS numberOfAlteredCases
FROM
mutation
INNER JOIN
mutation_event ON mutation_event.MUTATION_EVENT_ID = mutation.MUTATION_EVENT_ID
AND mutation_event.MUTATION_TYPE != 'Fusion'
INNER JOIN
genetic_profile ON mutation.GENETIC_PROFILE_ID = genetic_profile.GENETIC_PROFILE_ID
INNER JOIN
sample ON mutation.SAMPLE_ID = sample.INTERNAL_ID
INNER JOIN
gene ON mutation.ENTREZ_GENE_ID = gene.ENTREZ_GENE_ID
WHERE
mutation.SAMPLE_ID IN (SELECT
sample.INTERNAL_ID
FROM
sample
INNER JOIN
patient ON sample.PATIENT_ID = patient.INTERNAL_ID
INNER JOIN
genetic_profile ON patient.CANCER_STUDY_ID = genetic_profile.CANCER_STUDY_ID
WHERE
genetic_profile.STABLE_ID = 'ccle_broad_2019_mutations'
AND sample.STABLE_ID IN (...)
AND sample.INTERNAL_ID = mutation.SAMPLE_ID
AND genetic_profile.GENETIC_PROFILE_ID = mutation.GENETIC_PROFILE_ID)
GROUP BY mutation.ENTREZ_GENE_ID
用非常截断的样本列表解释慢速数据库：
+=====================================================================+======================================================================+=======+
| Query execution plan on DB2 (Slow) | Query execution plan on DB1 | Same? |
+=====================================================================+======================================================================+=======+
| id : 1, | id : 1, | Yes |
+---------------------------------------------------------------------+----------------------------------------------------------------------+-------+
| select_type : SIMPLE, | select_type : SIMPLE, | Yes |
+---------------------------------------------------------------------+----------------------------------------------------------------------+-------+
| table : mutation, | table : mutation, | Yes |
+---------------------------------------------------------------------+----------------------------------------------------------------------+-------+
| partitions : null, | partitions : null, | Yes |
+---------------------------------------------------------------------+----------------------------------------------------------------------+-------+
| type : ref, | type : ref, | Yes |
+---------------------------------------------------------------------+----------------------------------------------------------------------+-------+
| possible_keys : UQ_MUTATION_EVENT_ID_GENETIC_PROFILE_ID_SAMPLE_ID, | possible_keys : UQ_MUTATION_EVENT_ID_GENETIC_PROFILE_ID_SAMPLE_ID, | |
| GENETIC_PROFILE_ID,GENETIC_PROFILE_ID_2,GENETIC_PROFILE_ID_3, | GENETIC_PROFILE_ID,GENETIC_PROFILE_ID_2,GENETIC_PROFILE_ID_3, | |
| ENTREZ_GENE_ID,SAMPLE_ID,MUTATION_EVENT_ID, | ENTREZ_GENE_ID,SAMPLE_ID,MUTATION_EVENT_ID, | Yes |
+---------------------------------------------------------------------+----------------------------------------------------------------------+-------+
| key : GENETIC_PROFILE_ID, | key : GENETIC_PROFILE_ID_2, | No |
+---------------------------------------------------------------------+----------------------------------------------------------------------+-------+
| key_len : 4, | key_len : 8, | No |
+---------------------------------------------------------------------+----------------------------------------------------------------------+-------+
| ref : const, | ref : const,cgds_public.sample.INTERNAL_ID, | No |
+---------------------------------------------------------------------+----------------------------------------------------------------------+-------+
| rows : 792, | rows : 68, | No |
+---------------------------------------------------------------------+----------------------------------------------------------------------+-------+
| filtered : 0.01, | filtered : 100.00, | No |
+---------------------------------------------------------------------+----------------------------------------------------------------------+-------+
| Extra : Using where; Using index | Extra : null | No |
+--------------------------------------------------------------------------------------------------------------------------------------------+-------+
【问题讨论】：
-
Please edit your question 并包含您正在使用的查询以及
SHOW CREATE TABLE tablename和EXPLAIN your query（对于两个 db.tables）结果。 -
@tcadidot0 感谢您的回复。我刚刚发布了查询。对于 SHOW CREATE TABLE 和 EXPLAIN，所有表都需要这些吗？
-
也许您可以在上面发布的查询上运行
EXPLAIN。只需将EXPLAIN放在查询顶部（SELECT之前）并运行它。 -
“我有一个我认为是完美的数据库副本” 你是如何复制数据库的？请显示您使用的确切 SQL 命令。
-
@tcadidot0 我为两个数据库添加了 out of explain（相同的查询）。请注意，我将示例列表减少了两个。
标签： mysql sql mysql-workbench