Optimizer Feature Comparison Matrix
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| Feature | MariaDB 5.3/5.5 | MariaDB 10.0 | MySQL 5.5 | MySQL 5.6 (dev) |
|---|---|---|---|---|
| Disk access optimizations | ||||
Index Condition Pushdown (ICP) | YES | YES | - | YES |
Disk-sweep Multi-range read (DS-MRR) | YES | YES | - | YES |
DS-MRR with Key-ordered retrieval | YES | YES | - | - |
Index_merge / Sort_intersection | YES | YES | - | - |
Cost-based choice of range vs. index_merge | YES | YES | - | - |
ORDER BY ... LIMIT <small_limit> | - | coming | - | YES |
Use extended (hidden) primary keys for innodb/xtradb | YES (5.5) | YES | - | - |
| Join optimizations | ||||
Batched key access (BKA) | YES | YES | - | YES |
Block hash join | YES | YES | - | - |
User-set memory limits on all join buffers | YES | YES | - | - |
Apply early outer table ON conditions | YES | YES | - | - |
Null-rejecting conditions tested early for NULLs | YES | YES | - | - |
| Subquery optimizations | ||||
In-to-exists | YES | YES | YES | YES |
Semi-join | YES | YES | - | YES |
Materialization | YES | YES | - | YES |
NULL-aware Materialization | YES | YES | - | - |
Cost choice of materialization vs. in-to-exists | YES | YES | - | YES |
Subquery cache | YES | YES | - | - |
Fast explain with subqueries | YES | YES | - | - |
| Optimization for derived tables / views | ||||
Delayed materialization of derived tables / materialized views | YES | YES | - | YES |
Instant EXPLAIN for derived tables | YES | YES | - | YES |
Derived Table with Keys optimization | YES | YES | - | YES |
Fields of merge-able views and derived tables used in equality optimizations | YES | YES | - | - |
| Execution control | ||||
LIMIT ROWS EXAMINED rows_limit | YES (5.5) | YES | - | - |
| Optimizer control (optimizer switch) | ||||
Systematic control of all optimizer strategies | YES | YES | - | partial |
| EXPLAIN improvements | ||||
Explain for DELETE, INSERT, REPLACE, and UPDATE | - | coming | - | YES |
EXPLAIN in JSON format | - | - | - | YES |
More detailed and consistent EXPLAIN for subqueries | YES | YES | - | - |
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