Prefix index queries optimization¶
Percona Server for MySQL has ported Prefix Index Queries Optimization feature from 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¶
| Option | Description |
|---|---|
| Scope: | Global |
| Data type: | Numeric |
This variable shows the number of times secondary index lookup triggered cluster lookup.
Innodb_secondary_index_triggered_cluster_reads_avoided¶
| Option | Description |
|---|---|
| Scope: | Global |
| Data type: | Numeric |
This variable shows the number of times prefix optimization avoided triggering cluster lookup.
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