gistfile1.txt

| SELECT SUM(alias2.col_varchar_nokey) , alias2.pk AS field2 FROM t1 AS alias1
STRAIGHT_JOIN t2 AS alias2 ON alias2.pk = alias1.col_int_key WHERE alias1.pk
GROUP BY field2 ORDER BY alias1.col_int_key,alias2.pk | {
  "steps": [
    {
      "join_preparation": {
        "select#": 1,
        "steps": [
          {
            "expanded_query": "/* select#1 */ select sum(`alias2`.`col_varchar_nokey`) AS `SUM(alias2.col_varchar_nokey)`,`alias2`.`pk` AS `field2` from (`t1` `alias1` straight_join `t2` `alias2` on((`alias2`.`pk` = `alias1`.`col_int_key`))) where `alias1`.`pk` group by `field2` order by `alias1`.`col_int_key`,`alias2`.`pk`"
          },
          {
            "transformations_to_nested_joins": {
              "transformations": [
                "JOIN_condition_to_WHERE",
                "parenthesis_removal"
              ] /* transformations */,
              "expanded_query": "/* select#1 */ select sum(`alias2`.`col_varchar_nokey`) AS `SUM(alias2.col_varchar_nokey)`,`alias2`.`pk` AS `field2` from `t1` `alias1` straight_join `t2` `alias2` where (`alias1`.`pk` and (`alias2`.`pk` = `alias1`.`col_int_key`)) group by `field2` order by `alias1`.`col_int_key`,`alias2`.`pk`"
            } /* transformations_to_nested_joins */
          },
          {
            "functional_dependencies_of_GROUP_columns": {
              "all_columns_of_table_map_bits": [
                1
              ] /* all_columns_of_table_map_bits */,
              "columns": [
                "test.alias2.pk",
                "test.alias1.col_int_key"
              ] /* columns */
            } /* functional_dependencies_of_GROUP_columns */
          }
        ] /* steps */
      } /* join_preparation */
    },
    {
      "join_optimization": {
        "select#": 1,
        "steps": [
          {
            "condition_processing": {
              "condition": "WHERE",
              "original_condition": "(`alias1`.`pk` and (`alias2`.`pk` = `alias1`.`col_int_key`))",
              "steps": [
                {
                  "transformation": "equality_propagation",
                  "resulting_condition": "(`alias1`.`pk` and multiple equal(`alias2`.`pk`, `alias1`.`col_int_key`))"
                },
                {
                  "transformation": "constant_propagation",
                  "resulting_condition": "(`alias1`.`pk` and multiple equal(`alias2`.`pk`, `alias1`.`col_int_key`))"
                },
                {
                  "transformation": "trivial_condition_removal",
                  "resulting_condition": "(`alias1`.`pk` and multiple equal(`alias2`.`pk`, `alias1`.`col_int_key`))"
                }
              ] /* steps */
            } /* condition_processing */
          },
          {
            "substitute_generated_columns": {
            } /* substitute_generated_columns */
          },
          {
            "table_dependencies": [
              {
                "table": "`t1` `alias1`",
                "row_may_be_null": false,
                "map_bit": 0,
                "depends_on_map_bits": [
                ] /* depends_on_map_bits */
              },
              {
                "table": "`t2` `alias2`",
                "row_may_be_null": false,
                "map_bit": 1,
                "depends_on_map_bits": [
                  0
                ] /* depends_on_map_bits */
              }
            ] /* table_dependencies */
          },
          {
            "ref_optimizer_key_uses": [
              {
                "table": "`t2` `alias2`",
                "field": "pk",
                "equals": "`alias1`.`col_int_key`",
                "null_rejecting": true
              }
            ] /* ref_optimizer_key_uses */
          },
          {
            "rows_estimation": [
              {
                "table": "`t1` `alias1`",
                "table_scan": {
                  "rows": 20,
                  "cost": 0.25
                } /* table_scan */
              },
              {
                "table": "`t2` `alias2`",
                "const_keys_added": {
                  "keys": [
                    "PRIMARY"
                  ] /* keys */,
                  "cause": "group_by"
                } /* const_keys_added */,
                "range_analysis": {
                  "table_scan": {
                    "rows": 100,
                    "cost": 12.35
                  } /* table_scan */,
                  "potential_range_indexes": [
                    {
                      "index": "PRIMARY",
                      "usable": true,
                      "key_parts": [
                        "pk"
                      ] /* key_parts */
                    }
                  ] /* potential_range_indexes */,
                  "setup_range_conditions": [
                  ] /* setup_range_conditions */,
                  "group_index_range": {
                    "chosen": false,
                    "cause": "not_single_table"
                  } /* group_index_range */
                } /* range_analysis */
              }
            ] /* rows_estimation */
          },
          {
            "considered_execution_plans": [
              {
                "plan_prefix": [
                ] /* plan_prefix */,
                "table": "`t1` `alias1`",
                "best_access_path": {
                  "considered_access_paths": [
                    {
                      "rows_to_scan": 20,
                      "filtering_effect": [
                      ] /* filtering_effect */,
                      "final_filtering_effect": 0.9,
                      "access_type": "scan",
                      "resulting_rows": 18,
                      "cost": 2.25,
                      "chosen": true
                    }
                  ] /* considered_access_paths */
                } /* best_access_path */,
                "condition_filtering_pct": 100,
                "rows_for_plan": 18,
                "cost_for_plan": 2.25,
                "rest_of_plan": [
                  {
                    "plan_prefix": [
                      "`t1` `alias1`"
                    ] /* plan_prefix */,
                    "table": "`t2` `alias2`",
                    "best_access_path": {
                      "considered_access_paths": [
                        {
                          "access_type": "eq_ref",
                          "index": "PRIMARY",
                          "rows": 1,
                          "cost": 6.3,
                          "chosen": true,
                          "cause": "clustered_pk_chosen_by_heuristics"
                        },
                        {
                          "rows_to_scan": 100,
                          "filtering_effect": [
                          ] /* filtering_effect */,
                          "final_filtering_effect": 1,
                          "access_type": "scan",
                          "using_join_cache": true,
                          "buffers_needed": 1,
                          "resulting_rows": 100,
                          "cost": 180.25,
                          "chosen": false
                        }
                      ] /* considered_access_paths */
                    } /* best_access_path */,
                    "condition_filtering_pct": 100,
                    "rows_for_plan": 18,
                    "cost_for_plan": 8.55,
                    "chosen": true
                  }
                ] /* rest_of_plan */
              }
            ] /* considered_execution_plans */
          },
          {
            "attaching_conditions_to_tables": {
              "original_condition": "((`alias2`.`pk` = `alias1`.`col_int_key`) and `alias1`.`pk`)",
              "attached_conditions_computation": [
              ] /* attached_conditions_computation */,
              "attached_conditions_summary": [
                {
                  "table": "`t1` `alias1`",
                  "attached": "(`alias1`.`pk` and (`alias1`.`col_int_key` is not null))"
                },
                {
                  "table": "`t2` `alias2`",
                  "attached": null
                }
              ] /* attached_conditions_summary */
            } /* attaching_conditions_to_tables */
          },
          {
            "optimizing_distinct_group_by_order_by": {
              "simplifying_order_by": {
                "original_clause": "`alias1`.`col_int_key`,`alias2`.`pk`",
                "items": [
                  {
                    "item": "`alias1`.`col_int_key`"
                  },
                  {
                    "item": "`alias2`.`pk`",
                    "eq_ref_to_preceding_items": true
                  }
                ] /* items */,
                "resulting_clause_is_simple": true,
                "resulting_clause": "`alias1`.`col_int_key`"
              } /* simplifying_order_by */,
              "simplifying_group_by": {
                "original_clause": "`field2`",
                "items": [
                  {
                    "item": "`alias2`.`pk`"
                  }
                ] /* items */,
                "resulting_clause_is_simple": false,
                "resulting_clause": "`field2`"
              } /* simplifying_group_by */
            } /* optimizing_distinct_group_by_order_by */
          },
          {
            "refine_plan": [
              {
                "table": "`t1` `alias1`"
              },
              {
                "table": "`t2` `alias2`"
              }
            ] /* refine_plan */
          },
          {
            "considering_tmp_tables": [
              {
                "adding_tmp_table_in_plan_at_position": 2,
                "write_method": "continuously_update_group_row"
              },
              {
                "adding_sort_to_table_in_plan_at_position": 2
              } /* filesort */
            ] /* considering_tmp_tables */
          }
        ] /* steps */
      } /* join_optimization */
    },
    {
      "join_execution": {
        "select#": 1,
        "steps": [
          {
            "creating_tmp_table": {
              "tmp_table_info": {
                "table": "intermediate_tmp_table",
                "in_plan_at_position": 2,
                "columns": 3,
                "row_length": 18,
                "key_length": 4,
                "unique_constraint": false,
                "makes_grouped_rows": true,
                "cannot_insert_duplicates": false,
                "location": "TempTable"
              } /* tmp_table_info */
            } /* creating_tmp_table */
          },
          {
            "sorting_table_in_plan_at_position": 2,
            "filesort_information": [
              {
                "direction": "asc",
                "table": "intermediate_tmp_table",
                "field": "col_int_key"
              }
            ] /* filesort_information */,
            "filesort_priority_queue_optimization": {
              "usable": false,
              "cause": "not applicable (no LIMIT)"
            } /* filesort_priority_queue_optimization */,
            "filesort_execution": [
            ] /* filesort_execution */,
            "filesort_summary": {
              "memory_available": 262144,
              "key_size": 13,
              "row_size": 13,
              "max_rows_per_buffer": 18,
              "num_rows_estimate": 18,
              "num_rows_found": 8,
              "num_examined_rows": 8,
              "num_initial_chunks_spilled_to_disk": 0,
              "sort_buffer_size": 384,
              "sort_algorithm": "std::sort",
              "unpacked_addon_fields": "using_heap_table",
              "sort_mode": "<fixed_sort_key, rowid>"
            } /* filesort_summary */
          }
        ] /* steps */
      } /* join_execution */
    }
  ] /* steps */
} |                                 0 |                       0 |