我有一个大约运行 1.6 秒并返回 150Kish 行的查询。我一直在从这个查询构建一个基于内存引擎的临时表,这个操作大约需要 6.5 秒。我筛选了 mysql 站点上的大量文档以及临时表上的索引(当我有索引和没有索引时几乎没有任何区别)试图找到一些创建表的方法表现更好。关于可以加速创建内存临时表(或非临时表)的配置选项,是否有人有任何建议?要弄清楚我到底在寻找什么(我认为)是某种可能会提高创建速度的表配置选项。我已经浏览了 mysql 5.7 站点上列出的大部分内容,但似乎没有什么可以改变在内存中创建临时/标准表所需的时间。
CREATE TEMPORARY TABLE
IF NOT EXISTS myTempTable
(ugID INT,stID INT, INDEX st (`st`) )
ENGINE=MEMORY AS
select ugID, stID
from a_complex_query_that_runs_in_under_2_seconds_but_takes_6_to_write_to_a_temptable_with_150k_rows
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY <derived15> ALL NULL NULL NULL NULL 559
1 PRIMARY creatorEntity eq_ref PRIMARY PRIMARY 4 creatorAssignment.OwnerObjectID 1 Using index
1 PRIMARY <derived2> ALL NULL NULL NULL NULL 152580 Using where; Using join buffer
15 DERIVED VMAssignment ref AssociatedObjectID,AssociatedObject AssociatedObject 2 2902 Using where
2 DERIVED test_ range AssignmentValue,AssociatedObjectID,AssociatedObject,assignmentQuery AssociatedObjectID 4 NULL 214 Using where; Using temporary; Using filesort
2 DERIVED cfv_ ref CustomFieldID,EntityID,CFEntity,CFValue,CFEntityValue CustomFieldID 4 testCloud.test_.AssignmentValue 4232 Using where
2 DERIVED ent_ ref VMStoreID VMStoreID 4 testCloud.cfv_.EntityID 1 Using index
3 UNION test_ ref AssociatedObjectID,AssociatedObject AssociatedObject 2 2902 Using where; Using temporary; Using filesort
3 UNION cfv_ ref CustomFieldID,EntityID,CFEntity,CFValue,CFEntityValue CFValue 772 func,func 4 Using where
3 UNION ent_ ref VMStoreID VMStoreID 4 testCloud.cfv_.EntityID 1 Using index
4 UNION test_ const PRIMARY PRIMARY 4 1 Using index
5 UNION test_ index_merge AssociatedObjectID,AssociatedObject AssociatedObjectID,AssociatedObject 4,6 NULL 1 Using intersect(AssociatedObjectID,AssociatedObject); Using where; Using index; Using temporary; Using filesort
5 UNION entity_ ref PRIMARY,ClassName ClassName 2 23326 Using where
5 UNION ent_ ref VMStoreID VMStoreID 4 testCloud.entity_.ID 1 Using index
6 UNION entity_ ref PRIMARY,ClassName ClassName 2 23326 Using where; Using temporary; Using filesort
6 UNION ent_ ref VMStoreID VMStoreID 4 testCloud.entity_.ID 1 Using index
6 UNION test_ ref AssignmentValue,AssociatedObjectID,AssociatedObject,assignmentQuery AssignmentValue 768 testCloud.entity_.State 1 Using where
7 UNION entity_ ref PRIMARY,ClassName ClassName 2 23326 Using where; Using temporary; Using filesort
7 UNION ent_ ref VMStoreID VMStoreID 4 testCloud.entity_.ID 1 Using index
7 UNION test_ ref AssignmentValue,AssociatedObjectID,AssociatedObject,assignmentQuery AssignmentValue 768 testCloud.entity_.Zip 1 Using where
8 UNION test_ range AssociatedObjectID,AssociatedObject AssociatedObjectID 4 NULL 150 Using where; Using temporary; Using filesort
8 UNION entity_ ref PRIMARY,ClassName,Address Address 456 func,func 4 Using where
8 UNION ent_ ref VMStoreID VMStoreID 4 testCloud.entity_.ID 1 Using index
9 UNION test_ range AssignmentValue,AssociatedObjectID,AssociatedObject,assignmentQuery AssociatedObjectID 4 NULL 203 Using where; Using temporary; Using filesort
9 UNION ent_ ref VMStoreID VMStoreID 4 testCloud.test_.AssignmentValue 1 Using where; Using index
10 UNION test_ const PRIMARY PRIMARY 4 1 Using index
11 UNION test_ ref AssociatedObjectID,AssociatedObject AssociatedObjectID 4 1 Using where; Using temporary; Using filesort
11 UNION entity_ ref PRIMARY,ClassName ClassName 2 23326 Using where
11 UNION ent_ ref VMStoreID VMStoreID 4 testCloud.entity_.ID 1 Using index
12 UNION test_ ref AssignmentValue,AssociatedObjectID,AssociatedObject,assignmentQuery AssociatedObject 2 2902 Using where; Using temporary; Using filesort
12 UNION ent_ ref VMStoreID VMStoreID 4 testCloud.test_.AssignmentValue 1 Using where; Using index
13 UNION test_ range AssignmentValue,AssociatedObjectID,AssociatedObject,assignmentQuery AssociatedObjectID 4 NULL 239 Using where; Using temporary; Using filesort
13 UNION list_stores ref VMListID,VMStoreID,VMStoreID_2,VMStoreID_3,VMStoreID_4,VMStoreID_5,VMStoreID_6,VMStoreID_7,VMStoreID_8,VMStoreID_9,VMStoreID_10,VMStoreID_11,VMStoreID_12,VMStoreID_13,VMStoreID_14,VMStoreID_15,VMStoreID_16 VMListID 4 testCloud.test_.AssignmentValue 318 Using where
13 UNION ent_ ref VMStoreID VMStoreID 4 testCloud.list_stores.VMStoreID 1 Using index
14 UNION test_ range AssignmentValue,AssociatedObjectID,AssociatedObject,assignmentQuery AssociatedObjectID 4 NULL 70 Using where; Using temporary; Using filesort
14 UNION sto_ ref PRIMARY,RetailerID RetailerID 4 testCloud.test_.AssignmentValue 63 Using where; Using index
14 UNION ent_ ref VMStoreID VMStoreID 4 testCloud.sto_.ID 1 Using index
NULL UNION RESULT <union2,3,4,5,6,7,8,9,10,11,12,13,14> ALL NULL NULL NULL NULL NULL
最佳答案
没有太多可以使用的。 (SHOW CREATE TABLE
和 EXPLAIN
)但我确实看到了一件事:
Using intersect(AssociatedObjectID,AssociatedObject)
这几乎总是可以通过使用“复合”索引来改进:
INDEX(AssociatedObjectID, AssociatedObject)
复合索引可能还有其他情况,但我们需要查看查询。
“但是查询填充临时表所花费的时间”——创建 152K 行可能比插入那么多行花费的时间更长。
尝试使用 ENGINE=InnoDB
而不是 ENGINE=MEMORY
。 InnoDB 取得了性能上的飞跃。
也尝试不在 CREATE
中包含 INDEX st (st)
,而是在之后添加它。增量构建索引可能是CREATE
中最慢的部分。
可能没有影响 MEMORY
性能的可调参数。
关于mysql - 加快创建mysql表(from select),我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/44191208/