Performance Schema Statement Digests-opracowanie

Performance Schema Statement Digests
As of MySQL 5.6.5, the Performance Schema maintains statement digest information. Digesting
converts a SQL statement to normalized form and computes a hash value for the result. Normalization
permits statements that are similar to be grouped and summarized to expose information about the
types of statements the server is executing and how often they occur. This section describes how
statement normalizing occurs and how it can be useful.
Statement digesting involves these Performance Schema components:
• A statement_digest consumer in the setup_consumers table controls whether the
Performance Schema maintains digest information.
• The statement event tables (events_statements_current, events_statements_history,
and events_statements_history_long) have DIGEST and DIGEST_TEXT columns that
contain digest MD5 values and the corresponding normalized statement text strings.
• A events_statements_summary_by_digest table provides aggregated statement digest
information.
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