{
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        "select#": 1,
        "steps": [
          {
            "join_preparation": {
              "select#": 2,
              "steps": [
                {
                  "expanded_query": "/* select#2 */ select `posts`.`user_id` AS `user_id` from `posts` group by `posts`.`user_id`"
                }
              ]
            }
          },
          {
            "derived": {
              "table": " `t1`",
              "select#": 2,
              "materialized": true
            }
          },
          {
            "join_preparation": {
              "select#": 3,
              "steps": [
                {
                  "expanded_query": "/* select#3 */ select `posts`.`post_id` AS `post_id`,`posts`.`user_id` AS `user_id`,`posts`.`date_added` AS `date_added`,`posts`.`post_text` AS `post_text` from `posts` where (`t1`.`user_id` = `posts`.`user_id`) order by `posts`.`date_added` desc limit 3"
                }
              ]
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          },
          {
            "derived": {
              "table": " `t2`",
              "select#": 3,
              "materialized": true
            }
          },
          {
            "expanded_query": "/* select#1 */ select `t2`.`post_id` AS `post_id`,`t2`.`user_id` AS `user_id`,`t2`.`date_added` AS `date_added`,`t2`.`post_text` AS `post_text` from (/* select#2 */ select `posts`.`user_id` AS `user_id` from `posts` group by `posts`.`user_id`) `t1` join lateral (/* select#3 */ select `posts`.`post_id` AS `post_id`,`posts`.`user_id` AS `user_id`,`posts`.`date_added` AS `date_added`,`posts`.`post_text` AS `post_text` from `posts` where (`t1`.`user_id` = `posts`.`user_id`) order by `posts`.`date_added` desc limit 3) `t2`"
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            "join_optimization": {
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                      "depends_on_map_bits": [
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                          "chosen": true
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                          "cause": "has_group_by"
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                            "rows": 21,
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                {
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                      "best_access_path": {
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                            "rows_to_scan": 21,
                            "access_type": "range",
                            "range_details": {
                              "used_index": "index_for_group_by(user_id)"
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                            "resulting_rows": 21,
                            "cost": 11.55,
                            "chosen": true,
                            "use_tmp_table": true
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                        ]
                      },
                      "condition_filtering_pct": 100,
                      "rows_for_plan": 21,
                      "cost_for_plan": 11.55,
                      "sort_cost": 21,
                      "new_cost_for_plan": 32.55,
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                    }
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                    "attached_conditions_computation": [
                    ],
                    "attached_conditions_summary": [
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                        "attached": null
                      }
                    ]
                  }
                },
                {
                  "optimizing_distinct_group_by_order_by": {
                    "simplifying_group_by": {
                      "original_clause": "`posts`.`user_id`",
                      "items": [
                        {
                          "item": "`posts`.`user_id`"
                        }
                      ],
                      "resulting_clause_is_simple": true,
                      "resulting_clause": "`posts`.`user_id`"
                    }
                  }
                },
                {
                  "reconsidering_access_paths_for_index_ordering": {
                    "clause": "GROUP BY",
                    "steps": [
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                    "index_order_summary": {
                      "table": "`posts`",
                      "index_provides_order": true,
                      "order_direction": "asc",
                      "index": "user_id",
                      "plan_changed": false
                    }
                  }
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                {
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                {
                  "refine_plan": [
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                      "table": "`posts`"
                    }
                  ]
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                  "considering_tmp_tables": [
                  ]
                }
              ]
            }
          },
          {
            "join_optimization": {
              "select#": 3,
              "steps": [
                {
                  "condition_processing": {
                    "condition": "WHERE",
                    "original_condition": "(`t1`.`user_id` = `posts`.`user_id`)",
                    "steps": [
                      {
                        "transformation": "equality_propagation",
                        "resulting_condition": "(`t1`.`user_id` = `posts`.`user_id`)"
                      },
                      {
                        "transformation": "constant_propagation",
                        "resulting_condition": "(`t1`.`user_id` = `posts`.`user_id`)"
                      },
                      {
                        "transformation": "trivial_condition_removal",
                        "resulting_condition": "(`t1`.`user_id` = `posts`.`user_id`)"
                      }
                    ]
                  }
                },
                {
                  "substitute_generated_columns": {
                  }
                },
                {
                  "table_dependencies": [
                    {
                      "table": "`posts`",
                      "row_may_be_null": false,
                      "map_bit": 0,
                      "depends_on_map_bits": [
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                    }
                  ]
                },
                {
                  "ref_optimizer_key_uses": [
                    {
                      "table": "`posts`",
                      "field": "user_id",
                      "equals": "`t1`.`user_id`",
                      "null_rejecting": false
                    }
                  ]
                },
                {
                  "rows_estimation": [
                    {
                      "table": "`posts`",
                      "table_scan": {
                        "rows": 16024,
                        "cost": 24.25
                      }
                    }
                  ]
                },
                {
                  "considered_execution_plans": [
                    {
                      "plan_prefix": [
                      ],
                      "table": "`posts`",
                      "best_access_path": {
                        "considered_access_paths": [
                          {
                            "access_type": "ref",
                            "index": "user_id",
                            "rows": 801.2,
                            "cost": 152.87,
                            "chosen": true
                          },
                          {
                            "rows_to_scan": 16024,
                            "filtering_effect": [
                            ],
                            "final_filtering_effect": 1,
                            "access_type": "scan",
                            "resulting_rows": 16024,
                            "cost": 1626.7,
                            "chosen": false
                          }
                        ]
                      },
                      "condition_filtering_pct": 100,
                      "rows_for_plan": 801.2,
                      "cost_for_plan": 152.87,
                      "chosen": true
                    }
                  ]
                },
                {
                  "attaching_conditions_to_tables": {
                    "original_condition": "(`t1`.`user_id` = `posts`.`user_id`)",
                    "attached_conditions_computation": [
                    ],
                    "attached_conditions_summary": [
                      {
                        "table": "`posts`",
                        "attached": "(`t1`.`user_id` = `posts`.`user_id`)"
                      }
                    ]
                  }
                },
                {
                  "optimizing_distinct_group_by_order_by": {
                    "simplifying_order_by": {
                      "original_clause": "`posts`.`date_added` desc",
                      "items": [
                        {
                          "item": "`posts`.`date_added`"
                        }
                      ],
                      "resulting_clause_is_simple": true,
                      "resulting_clause": "`posts`.`date_added` desc"
                    }
                  }
                },
                {
                  "reconsidering_access_paths_for_index_ordering": {
                    "clause": "ORDER BY",
                    "steps": [
                    ],
                    "index_order_summary": {
                      "table": "`posts`",
                      "index_provides_order": false,
                      "order_direction": "undefined",
                      "index": "user_id",
                      "plan_changed": false
                    }
                  }
                },
                {
                  "finalizing_table_conditions": [
                    {
                      "table": "`posts`",
                      "original_table_condition": "(`t1`.`user_id` = `posts`.`user_id`)",
                      "final_table_condition   ": null
                    }
                  ]
                },
                {
                  "refine_plan": [
                    {
                      "table": "`posts`"
                    }
                  ]
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                {
                  "considering_tmp_tables": [
                    {
                      "adding_sort_to_table_in_plan_at_position": 0
                    }
                  ]
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              ]
            }
          },
          {
            "table_dependencies": [
              {
                "table": " `t1`",
                "row_may_be_null": false,
                "map_bit": 0,
                "depends_on_map_bits": [
                ]
              },
              {
                "table": " `t2`",
                "row_may_be_null": false,
                "map_bit": 1,
                "depends_on_map_bits": [
                  0
                ]
              }
            ]
          },
          {
            "rows_estimation": [
              {
                "table": " `t1`",
                "table_scan": {
                  "rows": 21,
                  "cost": 2.7625
                }
              },
              {
                "table": " `t2`",
                "table_scan": {
                  "rows": 3,
                  "cost": 2.5375
                }
              }
            ]
          },
          {
            "considered_execution_plans": [
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                "table": " `t1`",
                "best_access_path": {
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                    {
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                      "filtering_effect": [
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                      "final_filtering_effect": 1,
                      "access_type": "scan",
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                      "cost": 4.8625,
                      "chosen": true
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                  ]
                },
                "condition_filtering_pct": 100,
                "rows_for_plan": 21,
                "cost_for_plan": 4.8625,
                "rest_of_plan": [
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                    "plan_prefix": [
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                    ],
                    "table": " `t2`",
                    "best_access_path": {
                      "considered_access_paths": [
                        {
                          "lateral_materialization": {
                            "cost_for_one_run_of_inner_query": 152.87,
                            "cost_for_writing_to_tmp_table": 0.3,
                            "count_of_runs": 21,
                            "total_cost": 3216.5,
                            "cost_per_read": 153.17
                          }
                        },
                        {
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                          "access_type": "scan",
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                          "cost": 59.588,
                          "chosen": true
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                      ]
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                    "condition_filtering_pct": 100,
                    "rows_for_plan": 63,
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                    "chosen": true
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            "attaching_conditions_to_tables": {
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              "attached_conditions_summary": [
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                  "table": " `t1`",
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                },
                {
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                  "attached": null
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              ]
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            "finalizing_table_conditions": [
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          {
            "refine_plan": [
              {
                "table": " `t1`"
              },
              {
                "table": " `t2`",
                "rematerialized_for_each_row_of": "t1"
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                "row_length": 5,
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                "location": "TempTable"
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          {
            "creating_tmp_table": {
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            "join_execution": {
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