EXPLAIN FORMAT=JSON

Synopsis

EXPLAIN FORMAT=JSON is a variant of EXPLAIN command that produces output in JSON form. The output always has one row which has only one column titled "JSON". The content is a JSON representation of query plan, formatted for readability:

MariaDB [test]> EXPLAIN FORMAT=JSON SELECT * FROM t1 WHERE col1=1\G
*************************** 1. row ***************************
EXPLAIN: {
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "t1",
      "access_type": "ALL",
      "rows": 1000,
      "filtered": 100,
      "attached_condition": "(t1.col1 = 1)"
    }
  }
}

MariaDB's output for EXPLAIN FORMAT=JSON is different from MySQL's. There are multiple reasons for that

• MySQL's output has deficiencies (some are listed here: EXPLAIN FORMAT=JSON in MySQL)
• MariaDB has optimizations that MySQL does not have. Ergo, MariaDB generates query plans that MySQL does not generate.

EXPLAIN FORMAT=JSON output

[not yet complete] EXPLAIN FORMAT=JSON differences from MySQL.

TODO: Our separate EXPLAIN FORMAT=JSON docs.

See also

• ANALYZE FORMAT=JSON produces output like EXPLAIN FORMAT=JSON, but amended with the data from query execution.