5.6.4.3 Rewriter Query Rewrite Plugin Reference

id

The rule ID. This column is the table primary key. You can use the ID to uniquely identify any rule.

pattern

The template that indicates the pattern for statements that the rule matches. Use ? to represent parameter markers that match data values.

pattern_database

The database used to match unqualified table names in statements. Qualified table names in statements match qualified names in the pattern if corresponding database and table names are identical. Unqualified table names in statements match unqualified names in the pattern only if the default database is the same as pattern_database and the table names are identical.

replacement

The template that indicates how to rewrite statements matching the pattern column value. Use ? to represent parameter markers that match data values. In rewritten statements, the plugin replaces ? parameter markers in replacement using data values matched by the corresponding markers in pattern.

enabled

Whether the rule is enabled. Load operations (performed by invoking the flush_rewrite_rules() stored procedure) load the rule from the table into the Rewriter in-memory cache only if this column is YES.

This column makes it possible to deactivate a rule without removing it: Set the column to a value other than YES and reload the table into the plugin.

message

The plugin uses this column for communicating with users. If no error occurs when the rules table is loaded into memory, the plugin sets the message column to NULL. A non-NULL value indicates an error and the column contents are the error message. Errors can occur under these circumstances:

If a load error occurs, the plugin also sets the Rewriter_reload_error status variable to ON.

pattern_digest

This column is used for debugging and diagnostics. If the column exists when the rules table is loaded into memory, the plugin updates it with the pattern digest. This column may be useful if you are trying to determine why some statement fails to be rewritten.

normalized_pattern

This column is used for debugging and diagnostics. If the column exists when the rules table is loaded into memory, the plugin updates it with the normalized form of the pattern. This column may be useful if you are trying to determine why some statement fails to be rewritten.

flush_rewrite_rules()

This stored procedure uses the load_rewrite_rules() UDF to load the contents of the rewrite_rules table into the Rewriter in-memory cache.

Calling flush_rewrite_rules() implies COMMIT.

Invoke this procedure after you modify the rules table to cause the plugin to update its cache from the new table contents. If any errors occur, the plugin sets the message column for the appropriate rule rows in the table and sets the Rewriter_reload_error status variable to ON.

load_rewrite_rules()

This UDF is a helper routine used by the flush_rewrite_rules() stored procedure.

rewriter_enabled

Whether the Rewriter query rewrite plugin is enabled.

rewriter_verbose

For internal use.

Rewriter_number_loaded_rules

The number of rewrite plugin rewrite rules successfully loaded from the rewrite_rules table into memory for use by the Rewriter plugin.

Rewriter_number_reloads

The number of times the rewrite_rules table has been loaded into the in-memory cache used by the Rewriter plugin.

Rewriter_number_rewritten_queries

The number of queries rewritten by the Rewriter query rewrite plugin since it was loaded.

Rewriter_reload_error

Whether an error occurred the most recent time that the rewrite_rules table was loaded into the in-memory cache used by the Rewriter plugin. If the value is OFF, no error occurred. If the value is ON, an error occurred; check the message column of the rewriter_rules table for error messages.