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Performance Schema events_statements_summary_by_digest Table

This table aggregates statement events by schema and digest, providing execution counts, latency, and locking statistics for normalized queries.

The Performance Schema digest is a hashed, normalized form of a statement with the specific data values removed. It allows statistics to be gathered for similar kinds of statements.

The Performance Schema events_statements_summary_by_digest table records statement events summarized by schema and digest. It contains the following columns:

Column

Description

SCHEMA NAME

Database name. Records are summarised together with DIGEST.

DIGEST

. Records are summarised together with SCHEMA NAME.

The *_TIMER_WAIT columns only calculate results for timed events, as non-timed events have a NULL wait time.

The events_statements_summary_by_digest table is limited in size by the system variable. Once the limit has been reached and the table is full, all entries are aggregated in a row with a NULL digest. The COUNT_STAR value of this NULL row indicates how many digests are recorded in the row and therefore gives an indication of whether performance_schema_digests_size should be increased to provide more accurate statistics.

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