EXPLAIN\
SELECT table_a.id,\
       table_a.appUserId,\
       table_a.fecha,\
       table_a.failed,\
       table_a.successful,\
       table_a.warning,\
       table_a.statusId,\
       table_a.sname,\
       table_b.name AS source,\
       table_c.iispecid,\
       table_c.column_a,\
       table_c.column_b,\
       table_d.ispecid,\
       table_c.column_c\
FROM table_a\
LEFT JOIN table_b ON (table_b.id = table_a.sourceId)\
LEFT JOIN table_c ON (table_a.id = table_c.ipid)\
LEFT JOIN table_d ON (table_a.id = table_d.ipid)\
ORDER BY fecha\
LIMIT 21	{\
  "steps": [\
    {\
      "join_preparation": {\
        "select#": 1,\
        "steps": [\
          {\
            "expanded_query": "/* select#1 */ select `table_a`.`id` AS `id`,`table_a`.`appUserId` AS `appUserId`,`table_a`.`fecha` AS `fecha`,`table_a`.`failed` AS `failed`,`table_a`.`successful` AS `successful`,`table_a`.`warning` AS `warning`,`table_a`.`statusId` AS `statusId`,`table_a`.`sname` AS `sname`,`table_b`.`name` AS `source`,`table_c`.`iispecid` AS `iispecid`,`table_c`.`column_a` AS `column_a`,`table_c`.`column_b` AS `column_b`,`table_d`.`ispecid` AS `ispecid`,`table_c`.`column_c` AS `column_c` from (((`table_a` left join `table_b` on((`table_b`.`id` = `table_a`.`sourceId`))) left join `table_c` on((`table_a`.`id` = `table_c`.`ipid`))) left join `table_d` on((`table_a`.`id` = `table_d`.`ipid`))) order by `table_a`.`fecha` limit 21"\
          },\
          {\
            "transformations_to_nested_joins": {\
              "transformations": [\
                "parenthesis_removal"\
              ],\
              "expanded_query": "/* select#1 */ select `table_a`.`id` AS `id`,`table_a`.`appUserId` AS `appUserId`,`table_a`.`fecha` AS `fecha`,`table_a`.`failed` AS `failed`,`table_a`.`successful` AS `successful`,`table_a`.`warning` AS `warning`,`table_a`.`statusId` AS `statusId`,`table_a`.`sname` AS `sname`,`table_b`.`name` AS `source`,`table_c`.`iispecid` AS `iispecid`,`table_c`.`column_a` AS `column_a`,`table_c`.`column_b` AS `column_b`,`table_d`.`ispecid` AS `ispecid`,`table_c`.`column_c` AS `column_c` from `table_a` left join `table_b` on((`table_b`.`id` = `table_a`.`sourceId`)) left join `table_c` on((`table_a`.`id` = `table_c`.`ipid`)) left join `table_d` on((`table_a`.`id` = `table_d`.`ipid`)) order by `table_a`.`fecha` limit 21"\
            }\
          }\
        ]\
      }\
    },\
    {\
      "join_optimization": {\
        "select#": 1,\
        "steps": [\
          {\
            "condition_processing": {\
              "condition": "WHERE",\
              "original_condition": null,\
              "steps": [\
                {\
                  "transformation": "equality_propagation",\
                  "resulting_condition": null\
                }\
              ]\
            }\
          },\
          {\
            "substitute_generated_columns": {\
            }\
          },\
          {\
            "table_dependencies": [\
              {\
                "table": "`table_a`",\
                "row_may_be_null": false,\
                "map_bit": 0,\
                "depends_on_map_bits": [\
                ]\
              },\
              {\
                "table": "`table_b`",\
                "row_may_be_null": true,\
                "map_bit": 1,\
                "depends_on_map_bits": [\
                  0\
                ]\
              },\
              {\
                "table": "`table_c`",\
                "row_may_be_null": true,\
                "map_bit": 2,\
                "depends_on_map_bits": [\
                  0,\
                  1\
                ]\
              },\
              {\
                "table": "`table_d`",\
                "row_may_be_null": true,\
                "map_bit": 3,\
                "depends_on_map_bits": [\
                  0,\
                  1,\
                  2\
                ]\
              }\
            ]\
          },\
          {\
            "ref_optimizer_key_uses": [\
              {\
                "table": "`table_b`",\
                "field": "id",\
                "equals": "`table_a`.`sourceId`",\
                "null_rejecting": true\
              },\
              {\
                "table": "`table_c`",\
                "field": "ipid",\
                "equals": "`table_a`.`id`",\
                "null_rejecting": false\
              },\
              {\
                "table": "`table_d`",\
                "field": "ipid",\
                "equals": "`table_a`.`id`",\
                "null_rejecting": false\
              }\
            ]\
          },\
          {\
            "rows_estimation": [\
              {\
                "table": "`table_a`",\
                "table_scan": {\
                  "rows": 1973233,\
                  "cost": 4378.8\
                }\
              },\
              {\
                "table": "`table_b`",\
                "table_scan": {\
                  "rows": 8,\
                  "cost": 0.25\
                }\
              },\
              {\
                "table": "`table_c`",\
                "table_scan": {\
                  "rows": 1990701,\
                  "cost": 1594\
                }\
              },\
              {\
                "table": "`table_d`",\
                "table_scan": {\
                  "rows": 1,\
                  "cost": 0.25\
                }\
              }\
            ]\
          },\
          {\
            "considered_execution_plans": [\
              {\
                "plan_prefix": [\
                ],\
                "table": "`table_a`",\
                "best_access_path": {\
                  "considered_access_paths": [\
                    {\
                      "rows_to_scan": 1973233,\
                      "access_type": "scan",\
                      "resulting_rows": 1.97e6,\
                      "cost": 201702,\
                      "chosen": true\
                    }\
                  ]\
                },\
                "condition_filtering_pct": 100,\
                "rows_for_plan": 1.97e6,\
                "cost_for_plan": 201702,\
                "rest_of_plan": [\
                  {\
                    "plan_prefix": [\
                      "`table_a`"\
                    ],\
                    "table": "`table_b`",\
                    "best_access_path": {\
                      "considered_access_paths": [\
                        {\
                          "access_type": "eq_ref",\
                          "index": "PRIMARY",\
                          "rows": 1,\
                          "cost": 690632,\
                          "chosen": true,\
                          "cause": "clustered_pk_chosen_by_heuristics"\
                        },\
                        {\
                          "rows_to_scan": 8,\
                          "access_type": "scan",\
                          "using_join_cache": true,\
                          "buffers_needed": 7972,\
                          "resulting_rows": 8,\
                          "cost": 1.58e6,\
                          "chosen": false\
                        }\
                      ]\
                    },\
                    "condition_filtering_pct": 100,\
                    "rows_for_plan": 1.97e6,\
                    "cost_for_plan": 892334,\
                    "rest_of_plan": [\
                      {\
                        "plan_prefix": [\
                          "`table_a`",\
                          "`table_b`"\
                        ],\
                        "table": "`table_c`",\
                        "best_access_path": {\
                          "considered_access_paths": [\
                            {\
                              "access_type": "eq_ref",\
                              "index": "PRIMARY",\
                              "rows": 1,\
                              "cost": 690632,\
                              "chosen": true,\
                              "cause": "clustered_pk_chosen_by_heuristics"\
                            },\
                            {\
                              "rows_to_scan": 1990701,\
                              "access_type": "scan",\
                              "using_join_cache": true,\
                              "buffers_needed": 15710,\
                              "resulting_rows": 1.99e6,\
                              "cost": 3.9e11,\
                              "chosen": false\
                            }\
                          ]\
                        },\
                        "added_to_eq_ref_extension": true,\
                        "condition_filtering_pct": 100,\
                        "rows_for_plan": 1.97e6,\
                        "cost_for_plan": 1.58e6,\
                        "rest_of_plan": [\
                          {\
                            "plan_prefix": [\
                              "`table_a`",\
                              "`table_b`",\
                              "`table_c`"\
                            ],\
                            "table": "`table_d`",\
                            "best_access_path": {\
                              "considered_access_paths": [\
                                {\
                                  "access_type": "eq_ref",\
                                  "index": "PRIMARY",\
                                  "rows": 1,\
                                  "cost": 690632,\
                                  "chosen": true,\
                                  "cause": "clustered_pk_chosen_by_heuristics"\
                                },\
                                {\
                                  "access_type": "scan",\
                                  "chosen": false,\
                                  "cause": "covering_index_better_than_full_scan"\
                                }\
                              ]\
                            },\
                            "added_to_eq_ref_extension": true,\
                            "condition_filtering_pct": 100,\
                            "rows_for_plan": 1.97e6,\
                            "cost_for_plan": 2.27e6,\
                            "chosen": true\
                          }\
                        ]\
                      }\
                    ]\
                  }\
                ]\
              }\
            ]\
          },\
          {\
            "condition_on_constant_tables": "true",\
            "condition_value": true\
          },\
          {\
            "attaching_conditions_to_tables": {\
              "original_condition": "true",\
              "attached_conditions_computation": [\
              ],\
              "attached_conditions_summary": [\
                {\
                  "table": "`table_a`",\
                  "attached": null\
                },\
                {\
                  "table": "`table_b`",\
                  "attached": "<if>(is_not_null_compl(table_b), (`table_b`.`id` = `table_a`.`sourceId`), true)"\
                },\
                {\
                  "table": "`table_c`",\
                  "attached": "<if>(is_not_null_compl(table_c), (`table_c`.`ipid` = `table_a`.`id`), true)"\
                },\
                {\
                  "table": "`table_d`",\
                  "attached": "<if>(is_not_null_compl(table_d), (`table_d`.`ipid` = `table_a`.`id`), true)"\
                }\
              ]\
            }\
          },\
          {\
            "optimizing_distinct_group_by_order_by": {\
              "simplifying_order_by": {\
                "original_clause": "`table_a`.`fecha`",\
                "items": [\
                  {\
                    "item": "`table_a`.`fecha`"\
                  }\
                ],\
                "resulting_clause_is_simple": true,\
                "resulting_clause": "`table_a`.`fecha`"\
              }\
            }\
          },\
          {\
            "reconsidering_access_paths_for_index_ordering": {\
              "clause": "ORDER BY",\
              "steps": [\
              ],\
              "index_order_summary": {\
                "table": "`table_a`",\
                "index_provides_order": true,\
                "order_direction": "asc",\
                "index": "fecha",\
                "plan_changed": true,\
                "access_type": "index"\
              }\
            }\
          },\
          {\
            "finalizing_table_conditions": [\
              {\
                "table": "`table_b`",\
                "original_table_condition": "<if>(is_not_null_compl(table_b), (`table_b`.`id` = `table_a`.`sourceId`), true)",\
                "final_table_condition   ": null\
              },\
              {\
                "table": "`table_c`",\
                "original_table_condition": "<if>(is_not_null_compl(table_c), (`table_c`.`ipid` = `table_a`.`id`), true)",\
                "final_table_condition   ": null\
              },\
              {\
                "table": "`table_d`",\
                "original_table_condition": "<if>(is_not_null_compl(table_d), (`table_d`.`ipid` = `table_a`.`id`), true)",\
                "final_table_condition   ": null\
              }\
            ]\
          },\
          {\
            "refine_plan": [\
              {\
                "table": "`table_a`"\
              },\
              {\
                "table": "`table_b`"\
              },\
              {\
                "table": "`table_c`"\
              },\
              {\
                "table": "`table_d`"\
              }\
            ]\
          },\
          {\
            "considering_tmp_tables": [\
            ]\
          }\
        ]\
      }\
    },\
    {\
      "join_explain": {\
        "select#": 1,\
        "steps": [\
        ]\
      }\
    }\
  ]\
}	0	0