{
  "$schema": "https://myflames.dev/schemas/sidecar-v1.json",
  "schema_version": "1.3",
  "generated_at": "2026-04-25T12:51:28Z",
  "myflames_version": "1.5.0",
  "source": {
    "type": "file",
    "engine": "mysql",
    "fixture_path": "/Users/viniciusgrippa/Downloads/git/myflames/test/mysql-explain-index-merge-union.json"
  },
  "plan_summary": {
    "total_time_ms": 0.178,
    "rows_sent": 75,
    "rows_examined_estimate": 75,
    "operator_count": 4,
    "max_depth": 3
  },
  "optimizer_switches": [
    {
      "name": "index_merge",
      "value": "on",
      "explanation": "Uses two or more index range scans on the same table and combines row IDs (union/intersection/sort_union) instead of falling back to a full scan. A composite index is usually faster.",
      "node_labels": [
        "Deduplicate rows sorted by row ID"
      ]
    },
    {
      "name": "index_merge_union",
      "value": "on",
      "explanation": "Union variant of index_merge: OR'ed predicates are satisfied by scanning each index separately, then UNION'ing their row IDs.",
      "node_labels": [
        "Deduplicate rows sorted by row ID"
      ]
    }
  ],
  "warnings": [],
  "suggestions": [],
  "executive_summary": "Query runs 4 operators; returns 75 rows in 0.18 ms. No warnings.",
  "plan_tree": {
    "node_id": "n:4bc09dd3516c",
    "short_label": "Filter: (((t1.a = 50) or (t1.b = 100)))",
    "folded_label": "FILTER (((t1.a = 50) or (t1.b = 100))) starts=1 rows=75",
    "children": [
      {
        "node_id": "n:f85ded12d5b5",
        "short_label": "Deduplicate rows sorted by row ID",
        "folded_label": "Deduplicate rows sorted by row ID starts=1 rows=75",
        "children": [
          {
            "node_id": "n:395d4e419799",
            "short_label": "Index range scan [t1.idx_a]",
            "folded_label": "INDEX RANGE SCAN [t1.idx_a] starts=1 rows=50",
            "children": []
          },
          {
            "node_id": "n:3b024c1dd920",
            "short_label": "Index range scan [t1.idx_b]",
            "folded_label": "INDEX RANGE SCAN [t1.idx_b] starts=1 rows=25",
            "children": []
          }
        ]
      }
    ]
  },
  "query": {
    "raw": "/* select#1 */ select `testdb`.`t1`.`id` AS `id`,`testdb`.`t1`.`a` AS `a`,`testdb`.`t1`.`b` AS `b`,`testdb`.`t1`.`c` AS `c`,`testdb`.`t1`.`d` AS `d` from `testdb`.`t1` where ((`testdb`.`t1`.`a` = 50) or (`testdb`.`t1`.`b` = 100))",
    "beautified": "select testdb.t1.id AS id,testdb.t1.a AS a,testdb.t1.b AS b,testdb.t1.c AS c,testdb.t1.d AS d\nfrom testdb.t1\nwhere ((testdb.t1.a = 50) or (testdb.t1.b = 100))"
  },
  "teach_hooks": [
    {
      "lesson": "filter",
      "match": {
        "folded_label": "FILTER (((t1.a = 50) or (t1.b = 100))) starts=1 rows=75",
        "short_label": "Filter: (((t1.a = 50) or (t1.b = 100)))"
      },
      "controls": {
        "input_rows": 75,
        "selectivity": 10.0
      },
      "note": "Filter: ((t1.a = 50) or (t1.b = 100))",
      "query_sql": "/* select#1 */ select `testdb`.`t1`.`id` AS `id`,`testdb`.`t1`.`a` AS `a`,`testdb`.`t1`.`b` AS `b`,`testdb`.`t1`.`c` AS `c`,`testdb`.`t1`.`d` AS `d` from `testdb`.`t1` where ((`testdb`.`t1`.`a` = 50) or (`testdb`.`t1`.`b` = 100))"
    },
    {
      "lesson": "non_unique_lookup",
      "match": {
        "folded_label": "INDEX RANGE SCAN [t1.idx_a] starts=1 rows=50",
        "short_label": "Index range scan [t1.idx_a]"
      },
      "controls": {
        "rows": 50,
        "selectivity": 40.0,
        "covering": false
      },
      "note": "Index range scan on t1 using idx_a over (a = 50) (t1)",
      "query_sql": "/* select#1 */ select `testdb`.`t1`.`id` AS `id`,`testdb`.`t1`.`a` AS `a`,`testdb`.`t1`.`b` AS `b`,`testdb`.`t1`.`c` AS `c`,`testdb`.`t1`.`d` AS `d` from `testdb`.`t1` where ((`testdb`.`t1`.`a` = 50) or (`testdb`.`t1`.`b` = 100))"
    },
    {
      "lesson": "non_unique_lookup",
      "match": {
        "folded_label": "INDEX RANGE SCAN [t1.idx_b] starts=1 rows=25",
        "short_label": "Index range scan [t1.idx_b]"
      },
      "controls": {
        "rows": 25,
        "selectivity": 40.0,
        "covering": false
      },
      "note": "Index range scan on t1 using idx_b over (b = 100) (t1)",
      "query_sql": "/* select#1 */ select `testdb`.`t1`.`id` AS `id`,`testdb`.`t1`.`a` AS `a`,`testdb`.`t1`.`b` AS `b`,`testdb`.`t1`.`c` AS `c`,`testdb`.`t1`.`d` AS `d` from `testdb`.`t1` where ((`testdb`.`t1`.`a` = 50) or (`testdb`.`t1`.`b` = 100))"
    }
  ],
  "operator_complexities": [
    {
      "node_id": "n:f85ded12d5b5",
      "folded_label": "Deduplicate rows sorted by row ID starts=1 rows=75",
      "short_label": "Deduplicate rows sorted by row ID",
      "complexity": {
        "big_o": "O(Σ kᵢ)",
        "short": "Σ kᵢ",
        "severity": "medium",
        "rationale": "Index merge (union): each index scan returns kᵢ row IDs; merging them through a sorted-list union costs a pass over the total.",
        "confidence": "typical",
        "learn_more": "index_merge"
      }
    },
    {
      "node_id": "n:395d4e419799",
      "folded_label": "INDEX RANGE SCAN [t1.idx_a] starts=1 rows=50",
      "short_label": "Index range scan [t1.idx_a]",
      "complexity": {
        "big_o": "O(log n + k)",
        "short": "log n + k",
        "severity": "good",
        "rationale": "Index range scan: one B+tree descent to the range start, then a sequential walk over k matching index entries.",
        "confidence": "exact",
        "learn_more": "index_range_scan"
      }
    },
    {
      "node_id": "n:3b024c1dd920",
      "folded_label": "INDEX RANGE SCAN [t1.idx_b] starts=1 rows=25",
      "short_label": "Index range scan [t1.idx_b]",
      "complexity": {
        "big_o": "O(log n + k)",
        "short": "log n + k",
        "severity": "good",
        "rationale": "Index range scan: one B+tree descent to the range start, then a sequential walk over k matching index entries.",
        "confidence": "exact",
        "learn_more": "index_range_scan"
      }
    }
  ]
}