MySQL 8.0 Release Notes
MySQL 8.0 Source Code Documentation
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.
.frmfiles: Table metadata files. With the removal of.frmfiles:The 64KB table definition size limit imposed by the
.frmfile structure is removed.The
INFORMATION_SCHEMA.TABLESVERSIONcolumn reports a hardcoded value of10, which is the last.frmfile version used in MySQL 5.7.
.parfiles: Partition definition files.InnoDBstopped using partition definition files in MySQL 5.7 with the introduction of native partitioning support forInnoDBtables..TRNfiles: Trigger namespace files..TRGfiles: Trigger parameter files..islfiles:InnoDBSymbolic Link files containing the location of file-per-table tablespace files created outside of the data directory.db.optfiles: Database configuration files. These files, one per database directory, contained database default character set attributes.