A, B, C, D, E, F A total of 6 tables,
1. Through abcd associated query access to data access to 30 w table
2. By capturing the ef 20 w data
3. If the data from 30 w data contains 20 w, if through the SQL access to data, not the same 10 w

Tried a left outer join, no exists, found especially low efficiency, haven't found out a few hundred seconds
Tried in the program, and slowly slowly, do not know how,,,

CodePudding user response:

30 w of data and the data of 20 w matching conditions upon the index

CodePudding user response:

Dozens of W to hundreds of seconds, often is no index, use the explain to see the execution plan

CodePudding user response:

Usually use lead to no index or index