{ "steps": [ { "join_preparation": { "select#": 1, "steps": [ { "expanded_query": "/* select#1 */ select `test`.`A` AS `A`,`test`.`B` AS `B` from `test` where (`test`.`B` = 'foo') order by `test`.`B`" } ] } }, { "join_optimization": { "select#": 1, "steps": [ { "condition_processing": { "condition": "WHERE", "original_condition": "(`test`.`B` = 'foo')", "steps": [ { "transformation": "equality_propagation", "resulting_condition": "multiple equal('foo', `test`.`B`)" }, { "transformation": "constant_propagation", "resulting_condition": "multiple equal('foo', `test`.`B`)" }, { "transformation": "trivial_condition_removal", "resulting_condition": "multiple equal('foo', `test`.`B`)" } ] } }, { "substitute_generated_columns": { } }, { "table_dependencies": [ { "table": "`test`", "row_may_be_null": false, "map_bit": 0, "depends_on_map_bits": [ ] } ] }, { "ref_optimizer_key_uses": [ { "table": "`test`", "field": "B", "equals": "'foo'", "null_rejecting": false } ] }, { "rows_estimation": [ { "table": "`test`", "range_analysis": { "table_scan": { "rows": 1, "cost": 3.3 }, "potential_range_indexes": [ { "index": "PRIMARY", "usable": false, "cause": "not_applicable" }, { "index": "B", "usable": true, "key_parts": [ "B", "A" ] } ], "best_covering_index_scan": { "index": "B", "cost": 1.2, "chosen": true }, "setup_range_conditions": [ ], "group_index_range": { "chosen": false, "cause": "not_group_by_or_distinct" }, "analyzing_range_alternatives": { "range_scan_alternatives": [ { "index": "B", "ranges": [ "0x0300666f6f0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 <= B <= 0x0300666f6f0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000" ], "index_dives_for_eq_ranges": true, "rowid_ordered": true, "using_mrr": false, "index_only": true, "rows": 1, "cost": 1.21, "chosen": false, "cause": "cost" } ], "analyzing_roworder_intersect": { "usable": false, "cause": "too_few_roworder_scans" } } } } ] }, { "considered_execution_plans": [ { "plan_prefix": [ ], "table": "`test`", "best_access_path": { "considered_access_paths": [ { "access_type": "ref", "index": "B", "rows": 1, "cost": 1.2, "chosen": true }, { "access_type": "scan", "chosen": false, "cause": "covering_index_better_than_full_scan" } ] }, "condition_filtering_pct": 100, "rows_for_plan": 1, "cost_for_plan": 1.2, "chosen": true } ] }, { "attaching_conditions_to_tables": { "original_condition": "(`test`.`B` = 'foo')", "attached_conditions_computation": [ ], "attached_conditions_summary": [ { "table": "`test`", "attached": null } ] } }, { "clause_processing": { "clause": "ORDER BY", "original_clause": "`test`.`B`", "items": [ { "item": "`test`.`B`" } ], "resulting_clause_is_simple": true, "resulting_clause": "`test`.`B`" } }, { "added_back_ref_condition": "((`test`.`B` <=> 'foo'))" }, { "reconsidering_access_paths_for_index_ordering": { "clause": "ORDER BY", "index_order_summary": { "table": "`test`", "index_provides_order": false, "order_direction": "undefined", "index": "B", "plan_changed": false } } }, { "refine_plan": [ { "table": "`test`" } ] } ] } }, { "join_execution": { "select#": 1, "steps": [ { "filesort_information": [ { "direction": "asc", "table": "`test`", "field": "B" } ], "filesort_priority_queue_optimization": { "usable": false, "cause": "not applicable (no LIMIT)" }, "filesort_execution": [ ], "filesort_summary": { "rows": 0, "examined_rows": 0, "number_of_tmp_files": 0, "sort_buffer_size": 314496, "sort_mode": "" } } ] } } ] }