MySQL: integer Index vs Varchar Index

Question

Is there any performance problem with index field data type?

Is integer index much faster than varchar index?

Donal · Accepted Answer · 2014-09-17 07:02:26Z

22

An integer index is faster than a varchar index because an integer occupies a less space within the database than a varchar. Therefore, it is much faster to find an integer than it is to find a varchar string - because less memory is required to cache the integer index. A smaller data type, means more records can fit into the index blocks. The more records that fit into each index block - the fewer reads are needed to find records.

edited Sep 17, 2014 at 7:02

answered Sep 17, 2014 at 6:55

Donal

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OAH Over a year ago

an integer index will do the comparisons in Log(N) while the varchar index will do the comparisons in MLog(N) where M is the number of characters in the index. So that is by default an M fold speed increase.

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