feat: support EXPLAIN in mysql (#4235)

* feat: support EXPLAIN ANALYZE in mysql

* fix format

* remove write_sql

* add DESCRIBE_STATEMENT_STYLES

* move DESCRIBE_STATEMENT_STYLES

* use DESCRIBE_STYLES

* ops

sqlglot/dialects/mysql.py

@@ -187,6 +187,9 @@ class Tokenizer(tokens.Tokenizer):
  KEYWORDS = {
  **tokens.Tokenizer.KEYWORDS,
  "CHARSET": TokenType.CHARACTER_SET,
+ # The DESCRIBE and EXPLAIN statements are synonyms.
+ # https://dev.mysql.com/doc/refman/8.4/en/explain.html
+ "EXPLAIN": TokenType.DESCRIBE,
  "FORCE": TokenType.FORCE,
  "IGNORE": TokenType.IGNORE,
  "KEY": TokenType.KEY,

sqlglot/parser.py

@@ -1286,6 +1286,9 @@ class Parser(metaclass=_Parser):
 
  PRIVILEGE_FOLLOW_TOKENS = {TokenType.ON, TokenType.COMMA, TokenType.L_PAREN}
 
+ # The style options for the DESCRIBE statement
+ DESCRIBE_STYLES = {"ANALYZE", "EXTENDED", "FORMATTED", "HISTORY"}
+
  STRICT_CAST = True
 
  PREFIXED_PIVOT_COLUMNS = False
@@ -2567,7 +2570,7 @@ def _parse_returns(self) -> exp.ReturnsProperty:
 
  def _parse_describe(self) -> exp.Describe:
  kind = self._match_set(self.CREATABLES) and self._prev.text
- style = self._match_texts(("EXTENDED", "FORMATTED", "HISTORY")) and self._prev.text.upper()
+ style = self._match_texts(self.DESCRIBE_STYLES) and self._prev.text.upper()
  if self._match(TokenType.DOT):
  style = None
  self._retreat(self._index - 2)

tests/dialects/test_mysql.py

@@ -1305,3 +1305,12 @@ def test_grant(self):
  for sql in grant_cmds:
  with self.subTest(f"Testing MySQL's GRANT command statement: {sql}"):
  self.validate_identity(sql, check_command_warning=True)
+
+ def test_explain(self):
+ self.validate_identity(
+ "EXPLAIN ANALYZE SELECT * FROM t", "DESCRIBE ANALYZE SELECT * FROM t"
+ )
+
+ expression = self.parse_one("EXPLAIN ANALYZE SELECT * FROM t")
+ self.assertIsInstance(expression, exp.Describe)
+ self.assertEqual(expression.text("style"), "ANALYZE")