Memory

A memory storage engine is generally known as a heap storage engine. It is used for extremely fast access to data. This storage engine stores data in the RAM so that it wouldn't need I/O operations. As it stores data in the RAM, all data is lost upon server restart. This table is basically used for temporary tables or the lookup table. This engine supports table-level locking, which limits high write concurrency.

Important notes about memory tables are as follows:

• As memory table stores data in the RAM, which has a very limited storage capacity; if you try to write too much data into the memory table, it will start swapping data into the disk and then you lose the benefits of the memory storage engine.
• These tables don't support TEXT and BLOB data types, even such data types might not be required as it has limited storage capacity.
• This storage engine can be used to cache the results; lookup tables, for example, or postal codes and state names.
• Memory tables support B-tree indexes and Hash indexes.