error log eviction exception interceptor  A type of  log  showing information about MySQL startup and critical runtime errors and  crash  information. For details, see Section 5.4.2, “The Error Log” . See Also crash, log.  The process of removing an item from a cache or other temporary storage area, such as the  InnoDB buffer pool . Often, but not always, uses the  LRU  algorithm to determine which item to remove. When a  dirty page  is evicted, its contents are  flushed  to disk, and any dirty  neighbor pages  might be flushed also. See Also buffer pool, dirty page, flush, LRU, neighbor page.  A type of  interceptor  for tracing, debugging, or augmenting SQL errors encountered by a database application. For example, the interceptor code could issue a  SHOW WARNINGS  statement to retrieve additional information, and add descriptive text or even change the type of the exception returned to the application. Because the interceptor code is only called when SQL statements return errors, it does not impose any performance penalty on the application during normal (error-free) operation. In  Java  applications using  Connector/J , setting up this type of interceptor involves implementing the com.mysql.jdbc.ExceptionInterceptor  interface, and adding a  exceptionInterceptors  property to the  connection string . In  Visual Studio  applications using  Connector/NET , setting up this type of interceptor involves defining a class that inherits from the  BaseExceptionInterceptor  class and specifying that class name as part of the connection string. See Also Connector/J, Connector/NET, interceptor, Java, Visual Studio. exclusive lock  A kind of  lock  that prevents any other  transaction  from locking the same row. Depending on the transaction isolation level , this kind of lock might block other transactions from writing to the same row, or might also block other transactions from reading the same row. The default  InnoDB  isolation level,  REPEATABLE READ , enables higher  concurrency  by allowing transactions to read rows that have exclusive locks, a technique known as consistent read . See Also concurrency, consistent read, isolation level, lock, REPEATABLE READ, shared lock, transaction. extent  A group of  pages  within a  tablespace . For the default  page size  of 16KB, an extent contains 64 pages. In MySQL 5.6, the page size for an  InnoDB  instance can be 4KB, 8KB, or 16KB, controlled by the innodb_page_size  configuration option. For 4KB, 8KB, and 16KB pages sizes, the extent size is always 1MB (or 1048576 bytes). Support for 32KB and 64KB  InnoDB  page sizes was added in MySQL 5.7.6. For a 32KB page size, the extent size is 2MB. For a 64KB page size, the extent size is 4MB. InnoDB  features such as  segments ,  read-ahead  requests and the  doublewrite buffer  use I/O operations that read, write, allocate, or free data one extent at a time. See Also doublewrite buffer, page, page size, read-ahead, segment, tablespace. F .frm file  A file containing the metadata, such as the table definition, of a MySQL table.  .frm  files were removed in MySQL 8.0 but are still used in earlier MySQL releases. In MySQL 8.0, data previously stored in  .frm  files is stored in  data dictionary  tables. See Also data dictionary, MySQL Enterprise Backup, system tablespace. 6150