The MySQL Archive storage engine is a storage engine for the [[MySQL]] relational database management system. It is an analytic storage engine which allows a user to create a table which is "archive" only. No data can be deleted from the table, only added. The Archive engine uses a compression strategy based around the [[Zlib]] library. It takes a row and packs it by using a bit header to represent nulls and removes all whitespace for character type fields. Once this is done the row is then inserted into the compression buffer and waits to be flushed to disk based on either an explicit flush table, a read, or by the closing of the table.
The engine is notnether durable,and it is notnor [[ACID]] compliant. Unlike [[OLTP]] engines it uses a "stream" format to disk with no block boundaries. The head of the file generated is a byte array representing the data format and contents of the file.
Despite its use of zlib it is not compatible with gzio, the basis of the gzip tools. It uses its own azio system which is a fork of gzio.
