79451

compact and redundant Row Formats

Early versions of InnoDB used an unnamed file format (now called Antelope) for database files. With

that file format, tables are defined with row_format=compact or ROW_FORMAT= REDUNDANT. InnoDB

Stores up to the first 768 bytes of variable-length columns (such as BLOB and varchar) in the index

record within the B-tree node, with the remainder stored on the overflow pages.

To preserve compatibility with those prior versions, tables created with the newest InnoDB default

to the compact row format. See Section 5.4.8.3, “dynamic and compressed Row Formats” for

information about the newer dynamic and compressed row formats. With the Antelope file format, if the value of a column is 768 bytes or less, no overflow page is needed,

and some savings in 1/0 may result, sińce the value is in the B-tree node. This works well for relatively

short blobs, but may cause B-tree nodes to fili with data rather than key values, reducing their

efficiency. Tables with many blob columns could cause B-tree nodes to become too fuli of data,

and contain too few rows, making the entire index less efficient than if the rows were shorter or if the column values were stored off-page.

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