checkpoint  As changes are made to data pages that are cached in the  buffer pool , those changes are written to the  data files  sometime later, a process known as  flushing . The checkpoint is a record of the latest changes (represented by an  LSN  value) that have been successfully written to the data files. See Also buffer pool, data files, flush, fuzzy checkpointing, LSN. checksum  In  InnoDB , a validation mechanism to detect corruption when a  page  in a  tablespace  is read from disk into the InnoDB buffer pool . This feature is controlled by the  innodb_checksums  configuration option in MySQL 5.5. innodb_checksums  is deprecated in MySQL 5.6.3, replaced by  innodb_checksum_algorithm . The  innochecksum  command helps diagnose corruption problems by testing the checksum values for a specified  tablespace  file while the MySQL server is shut down. MySQL also uses checksums for replication purposes. For details, see the configuration options binlog_checksum ,  master_verify_checksum , and  slave_sql_verify_checksum . See Also buffer pool, page, tablespace. child table  In a  foreign key  relationship, a child table is one whose rows refer (or point) to rows in another table with an identical value for a specific column. This is the table that contains the  FOREIGN KEY ... REFERENCES clause and optionally  ON UPDATE  and  ON DELETE  clauses. The corresponding row in the  parent table  must exist before the row can be created in the child table. The values in the child table can prevent delete or update operations on the parent table, or can cause automatic deletion or updates in the child table, based on the  ON CASCADE  option used when creating the foreign key. See Also foreign key, parent table. clean page  A  page  in the  InnoDB buffer pool  where all changes made in memory have also been written ( flushed ) to the data files. The opposite of a  dirty page . See Also buffer pool, data files, dirty page, flush, page. clean shutdown  A  shutdown  that completes without errors and applies all changes to  InnoDB  tables before finishing, as opposed to a  crash  or a  fast shutdown . Synonym for  slow shutdown . See Also crash, fast shutdown, shutdown, slow shutdown. client  A program that runs outside the database server, communicating with the database by sending requests through a  Connector , or an  API  made available through  client libraries . It can run on the same physical machine as the database server, or on a remote machine connected over a network. It can be a special-purpose database application, or a general-purpose program like the  mysql  command-line processor. See Also API, client libraries, connector, mysql, server. client libraries  Files containing collections of functions for working with databases. By compiling your program with these libraries, or installing them on the same system as your application, you can run a database application (known as a  client ) on a machine that does not have the MySQL server installed; the application accesses the database over a network. With MySQL, you can use the  libmysqlclient  library from the MySQL server itself. See Also client, libmysqlclient. client-side prepared statement  A type of  prepared statement  where the caching and reuse are managed locally, emulating the functionality of server-side prepared statements . Historically, used by some  Connector/J ,  Connector/ODBC , and  Connector/ PHP  developers to work around issues with server-side stored procedures. With modern MySQL server versions, server-side prepared statements are recommended for performance, scalability, and memory efficiency. 6139