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Prefix Index Queries Optimization

Percona Server for MySQL 5.6 has ported the Prefix Index Queries Optimization feature from the Facebook patch for MySQL.

Prior to this InnoDB would always fetch the clustered index for all prefix columns in an index, even when the value of a particular record was smaller than the prefix length. This implementation optimizes that case to use the record from the secondary index and avoid the extra lookup.

Status Variables

Innodb_secondary_index_triggered_cluster_reads

Implemented in Percona Server for MySQL 5.7.18-14.

Option Description
Data type Numeric
Scope Global

This variable shows the number of times secondary index lookup triggered cluster lookup.

Innodb_secondary_index_triggered_cluster_reads_avoided

Implemented in Percona Server for MySQL 5.7.18-14.

Option Description
Data type Numeric
Scope Global
This variable shows the number of times prefix optimization avoided
triggering cluster lookup.