MySQL 8.0 Reference Manual  /  MySQL Data Dictionary  /  Removal of File-based Metadata Storage

Pre-General Availability Draft: 2017-05-26

15.2 Removal of File-based Metadata Storage

In previous MySQL releases, dictionary data was partially stored in metadata files. Issues with file-based metadata storage included expensive file scans, susceptibility to file system-related bugs, complex code for handling of replication and crash recovery failure states, and a lack of extensibility that made it difficult to add metadata for new features and relational objects.

The metadata files listed below are removed from MySQL. Unless otherwise noted, data previously stored in metadata files is now stored in data dictionary tables.

  • .frm files: Table metadata files. With the removal of .frm files:

    • The 64KB table definition size limit imposed by the .frm file structure is removed.

    • the INFORMATION_SCHEMA.TABLES VERSION column now reports a hardcoded value of 10, which is the last frm file version used in MySQL 5.7.

  • .par files: Partition definition files. .par files were removed in MySQL 5.7.6 with the introduction of native partitioning for InnoDB tables.

  • .TRN files: Trigger namespace files.

  • .TRG files: Trigger parameter files.

  • .isl files: InnoDB Symbolic Link files containing the location of file-per-table tablespace files created outside of the MySQL data directory. Redo log records are now used to locate remote tablespace files.

  • db.opt files: Database configuration files. These files, one per database directory, contained database default character set attributes.


User Comments
Sign Up Login You must be logged in to post a comment.