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Use WHERE ID IN, temporary tables and batch sample analysis, many novices are not very clear about this, in order to help you solve this problem, the following editor will explain in detail for you, people with this need can come to learn, I hope you can get something.

When the number of records to be queried is very large, use IN or temporary tables?

We know that using WHERE ID IN (...) Statement, if ID has indexed, SQL will use the index when executing.

One theory is that when the number of queries in IN is very large, MySQL cannot use indexes, so you need to use a temporary table to save id, and then join temporary table queries.

After practical testing, it is found that the index will not be used when the number of in records in MySQL exceeds the total number of records. In addition, use id in (...) The condition to worry about is that MySQL has a limit on the length of a single statement, controlled by the sysvar_max_allowed_packet parameter, which defaults to 1m. So, in general, use id in (...) There is no problem, for cases where the query data is large, it is recommended to retain the use of temporary tables.

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