feat(clickhouse): add support for ALTER TABLE REPLACE PARTITION state…

…ment (#3441)

* feat(clickhouse): add support for ALTER TABLE REPLACE PARTITION statement

* feat(clickhouse): add support for ALTER TABLE REPLACE PARTITION statement

Co-authored-by: Jo <46752250+georgesittas@users.noreply.github.com>

* feat(clickhouse): add support for replace partition expression

* feat(clickhouse): add support for ALTER TABLE REPLACE PARTITION statement

---------

Co-authored-by: Jo <46752250+georgesittas@users.noreply.github.com>

sqlglot/dialects/clickhouse.py

@@ -353,6 +353,11 @@ class Parser(parser.Parser):
             "CODEC": lambda self: self._parse_compress(),
         }
 
+        ALTER_PARSERS = {
+            **parser.Parser.ALTER_PARSERS,
+            "REPLACE": lambda self: self._parse_alter_table_replace(),
+        }
+
         SCHEMA_UNNAMED_CONSTRAINTS = {
             *parser.Parser.SCHEMA_UNNAMED_CONSTRAINTS,
             "INDEX",
@@ -593,6 +598,16 @@ def _parse_partition(self) -> t.Optional[exp.Partition]:
 
             return self.expression(exp.Partition, expressions=expressions)
 
+        def _parse_alter_table_replace(self) -> t.Optional[exp.Expression]:
+            partition = self._parse_partition()
+
+            if not partition or not self._match(TokenType.FROM):
+                return None
+
+            return self.expression(
+                exp.ReplacePartition, expression=partition, source=self._parse_table_parts()
+            )
+
     class Generator(generator.Generator):
         QUERY_HINTS = False
         STRUCT_DELIMITER = ("(", ")")
@@ -849,3 +864,8 @@ def partition_sql(self, expression: exp.Partition) -> str:
 
         def partitionid_sql(self, expression: exp.PartitionId) -> str:
             return f"ID {self.sql(expression.this)}"
+
+        def replacepartition_sql(self, expression: exp.ReplacePartition) -> str:
+            return (
+                f"REPLACE {self.sql(expression.expression)} FROM {self.sql(expression, 'source')}"
+            )

sqlglot/expressions.py

@@ -4191,6 +4191,11 @@ class DropPartition(Expression):
     arg_types = {"expressions": True, "exists": False}
 
 
+# https://clickhouse.com/docs/en/sql-reference/statements/alter/partition#replace-partition
+class ReplacePartition(Expression):
+    arg_types = {"expression": True, "source": True}
+
+
 # Binary expressions like (ADD a b)
 class Binary(Condition):
     arg_types = {"this": True, "expression": True}

tests/dialects/test_clickhouse.py

@@ -432,6 +432,13 @@ def test_clickhouse(self):
         )
         self.validate_identity("ALTER TABLE visits DROP PARTITION ID '201901'")
 
+        self.validate_identity("ALTER TABLE visits REPLACE PARTITION 201901 FROM visits_tmp")
+        self.validate_identity("ALTER TABLE visits REPLACE PARTITION ALL FROM visits_tmp")
+        self.validate_identity(
+            "ALTER TABLE visits REPLACE PARTITION tuple(toYYYYMM(toDate('2019-01-25'))) FROM visits_tmp"
+        )
+        self.validate_identity("ALTER TABLE visits REPLACE PARTITION ID '201901' FROM visits_tmp")
+
     def test_cte(self):
         self.validate_identity("WITH 'x' AS foo SELECT foo")
         self.validate_identity("WITH ['c'] AS field_names SELECT field_names")