Removal of File-based Metadata Storage mysql>  SHOW CREATE TABLE mysql.catalogs\G 14.2 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 reports a hardcoded value of  10 , which is the last  .frm  file version used in MySQL 5.7. • .par  files: Partition definition files.  InnoDB  stopped using partition definition files in MySQL 5.7 with the introduction of native partitioning support 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 data directory. • db.opt  files: Database configuration files. These files, one per database directory, contained database default character set attributes. • ddl_log.log  file: The file contained records of metadata operations generated by data definition statements such as  DROP TABLE  and  ALTER TABLE . 14.3 Transactional Storage of Dictionary Data 14.4 Dictionary Object Cache The data dictionary schema stores dictionary data in transactional ( InnoDB ) tables. Data dictionary tables are located in the  mysql  database together with non-data dictionary system tables. Data dictionary tables are created in a single  InnoDB  tablespace named  mysql.ibd , which resides in the MySQL data directory. The  mysql.ibd  tablespace file must reside in the MySQL data directory and its name cannot be modified or used by another tablespace. Dictionary data is protected by the same commit, rollback, and crash-recovery capabilities that protect user data that is stored in  InnoDB  tables. The dictionary object cache is a shared global cache that stores previously accessed data dictionary objects in memory to enable object reuse and minimize disk I/O. Similar to other cache mechanisms used by MySQL, the dictionary object cache uses an LRU-based eviction strategy to evict least recently used objects from memory. The dictionary object cache comprises cache partitions that store different object types. Some cache partition size limits are configurable, whereas others are hardcoded. 2991