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13.5.10. Maria FAQ

The following entries cover some of the frequently asked questions about Maria.

Questions

  • 13.5.10.1: Is there compression of text/blob columns or entire pages in Maria?

  • 13.5.10.2: Is DELAY_KEY_WRITE honored on Maria tables?

Questions and Answers

13.5.10.1: Is there compression of text/blob columns or entire pages in Maria?

No, there is no compression of TEXT/BLOB in Maria. You can use the compress()/uncompress() functions on the SQL level to store/retrieve BLOB/TEXT in compressed format.

13.5.10.2: Is DELAY_KEY_WRITE honored on Maria tables?

If you are using nontransactional Maria tables (CREATE TABLE... ENGINE=MARIA TRANSACTIONAL=0), which are similar to MyISAM, then DELAY_KEY_WRITE works as you expect. If you are using transactional Maria tables (the default), then DELAY_KEY_WRITE is always enabled. In MyISAM and nontransactional Maria tables (which have no logging), by default all the table's key pages are flushed to the OS at the end of each statement, to guarantee some durability. DELAY_KEY_WRITE removes this flush, giving less durability. In transactional Maria tables, key pages are flushed by a background job, regularly, not necessarily at the end of each statement, and durability is guaranteed thanks to logging.