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Consider usingMEMORY tables for noncritical data that is accessed often, and is read-only or rarely updated. Benchmark your application against equivalentInnoDB orMyISAM tables under a realistic workload, to confirm that any additional performance is worth the risk of losing data, or the overhead of copying data from a disk-based table at application start.

For best performance withMEMORY tables, examine the kinds of queries against each table, and specify the type to use for each associated index, either a B-tree index or a hash index. On theCREATE INDEX statement, use the clauseUSING BTREE orUSING HASH. B-tree indexes are fast for queries that do greater-than or less-than comparisons through operators such as> orBETWEEN. Hash indexes are only fast for queries that look up single values through the= operator, or a restricted set of values through theIN operator. For whyUSING BTREE is often a better choice than the defaultUSING HASH, seeSection 10.2.1.23, “Avoiding Full Table Scans”. For implementation details of the different types ofMEMORY indexes, seeSection 10.3.9, “Comparison of B-Tree and Hash Indexes”.