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 contents are a JSON representation of the query plan:

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)"  }  } }

Output is different from MySQL

The output of MariaDB's EXPLAIN FORMAT=JSON is different from EXPLAIN FORMAT=JSON in MySQL. The reasons for that are:

• MySQL's output has deficiencies.

• The output of MySQL's EXPLAIN FORMAT=JSON is not defined. Even MySQL Workbench has trouble parsing it (see this blog post).

• MariaDB has query optimizations that MySQL does not have. This means that MariaDB generates query plans that MySQL does not generate.

Output Format

TODO: MariaDB's output format description.

See Also

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

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