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The maximum amount of memory available to the parser. The default value places no limit on memory available. The value can be reduced to protect against out-of-memory situations caused by parsing long or complex SQL statements. 

• partial_revokes 

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Enabling this variable makes it possible to revoke privileges partially. Specifically, for users who have privileges at the global level, partial_revokes  enables privileges for specific schemas to be revoked while leaving the privileges in place for other schemas. For example, a user who has the global UPDATE privilege can be restricted from exercising this privilege on the mysql  system schema. (Or, stated another way, the user is enabled to exercise the UPDATE  privilege on all schemas except the mysql schema.) In this sense, the user’s global UPDATE  privilege is partially revoked. 

Once enabled, partial_revokes  cannot be disabled if any account has privilege restrictions. If any such account exists, disabling partial_revokes  fails: 

•For attempts to disable partial_revokes  at startup, the server logs an error message and enables partial_revokes . 

•For attempts to disable partial_revokes  at runtime, an error occurs and the partial_revokes value remains unchanged. 

To disable partial_revokes  in this case, first modify each account that has partially revoked privileges, either by re-granting the privileges or by removing the account. 

For more information, including instructions for removing partial revokes, see Section 6.2.12, “Privilege Restriction Using Partial Revokes” . 

• password_history 

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