MySQL Archive: Difference between revisions

Revision as of 22:23, 8 March 2008

Revision as of 15:41, 13 May 2008

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The engine is not [[ACID]] compliant. Unlike [[OLTP]] engines, it uses a "stream" format to disk with no block boundaries. The head of the Archive file generated is a byte array representing the data format and contents of that file. In MySQL 5.1, a copy of the MySQL FRM file is stored in the header of each Archive file. The FRM file, which represents the definition of a table, allows an Archive file to be restored to a MySQL server if the Archive file is copied to the server.

Despite the use of [[zlib]], Archive files are not compatible with [[gziogzip]], the basis of the [[gzip]] tools. It uses its own azio system that is a fork of gzio.

Archive differs from the other MySQL analytical engine, [[MyISAM]], by being a row level locking engine and by keeping a constant version snapshot throughout a single query (making it [[Multiversion concurrency control|MVCC]]). This means that Archive does not lock for concurrent bulk inserts. For bulk inserts it performs an interlaced INSERT, so unlike MyISAM, order is not guaranteed.