support for ALTER CONVERSION

postgres/parser/parser/sql.y

@@ -757,6 +757,7 @@ func (u *sqlSymUnion) aggregateArg() *tree.AggregateArg {
 
 %type <tree.Statement> alter_aggregate_stmt
 %type <tree.Statement> alter_collation_stmt
+%type <tree.Statement> alter_conversion_stmt
 
 %type <tree.Statement> backup_stmt
 %type <tree.Statement> begin_stmt
@@ -1272,11 +1273,12 @@ stmt:
 // %Category: Group
 // %Text: ALTER TABLE, ALTER INDEX, ALTER VIEW, ALTER SEQUENCE, ALTER DATABASE, ALTER USER, ALTER ROLE
 alter_stmt:
-  alter_ddl_stmt       // help texts in sub-rule
-| alter_role_stmt      // EXTEND WITH HELP: ALTER ROLE
-| alter_collation_stmt // EXTEND WITH HELP: ALTER COLLATION
-| alter_aggregate_stmt // EXTEND WITH HELP: ALTER AGGREGATE
-| ALTER error          // SHOW HELP: ALTER
+  alter_ddl_stmt        // help texts in sub-rule
+| alter_role_stmt       // EXTEND WITH HELP: ALTER ROLE
+| alter_aggregate_stmt  // EXTEND WITH HELP: ALTER AGGREGATE
+| alter_collation_stmt  // EXTEND WITH HELP: ALTER COLLATION
+| alter_conversion_stmt // EXTEND WITH HELP: ALTER CONVERSION
+| ALTER error           // SHOW HELP: ALTER
 
 alter_ddl_stmt:
   alter_table_stmt     // EXTEND WITH HELP: ALTER TABLE
@@ -2181,6 +2183,20 @@ alter_collation_stmt:
     $$.val = &tree.AlterCollation{Name: tree.Name($3), Schema: $4}
   }
 
+alter_conversion_stmt:
+  ALTER CONVERSION unrestricted_name RENAME TO unrestricted_name
+  {
+    $$.val = &tree.AlterConversion{Name: tree.Name($3), Rename: tree.Name($6)}
+  }
+| ALTER CONVERSION unrestricted_name opt_owner_to
+  {
+    $$.val = &tree.AlterConversion{Name: tree.Name($3), Owner: $4}
+  }
+| ALTER CONVERSION unrestricted_name opt_set_schema
+  {
+    $$.val = &tree.AlterConversion{Name: tree.Name($3), Schema: $4}
+  }
+
 alter_attribute_action_list:
   alter_attribute_action
 | alter_attribute_action_list ',' alter_attribute_action

postgres/parser/sem/tree/alter_conversion.go

@@ -0,0 +1,60 @@
+// Copyright 2023 Dolthub, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Copyright 2020 The Cockroach Authors.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+package tree
+
+//ALTER COLLATION name REFRESH VERSION
+
+//ALTER COLLATION name RENAME TO new_name
+//ALTER COLLATION name OWNER TO { new_owner | CURRENT_ROLE | CURRENT_USER | SESSION_USER }
+//ALTER COLLATION name SET SCHEMA new_schema
+
+var _ Statement = &AlterConversion{}
+
+// AlterConversion represents a ALTER COLLATION statement.
+type AlterConversion struct {
+	Name           Name
+	RefreshVersion bool
+	Rename         Name
+	Owner          string
+	Schema         string
+}
+
+// Format implements the NodeFormatter interface.
+func (node *AlterConversion) Format(ctx *FmtCtx) {
+	ctx.WriteString("ALTER COLLATION ")
+	ctx.FormatNode(&node.Name)
+	if node.RefreshVersion {
+		ctx.WriteString(" REFRESH VERSION")
+	} else if node.Rename != "" {
+		ctx.WriteString(" RENAME ")
+		ctx.FormatNode(&node.Rename)
+	} else if node.Owner != "" {
+		ctx.WriteString(" OWNER TO ")
+		ctx.FormatNameP(&node.Owner)
+	} else if node.Schema != "" {
+		ctx.WriteString(" SET SCHEMA ")
+		ctx.FormatNameP(&node.Schema)
+	}
+}

postgres/parser/sem/tree/stmt.go

@@ -200,6 +200,14 @@ func (*AlterCollation) StatementTag() string { return "ALTER COLLATION" }
 
 func (*AlterCollation) hiddenFromShowQueries() {}
 
+// StatementType implements the Statement interface.
+func (*AlterConversion) StatementType() StatementType { return DDL }
+
+// StatementTag returns a short string identifying the type of statement.
+func (*AlterConversion) StatementTag() string { return "ALTER CONVERSION" }
+
+func (*AlterConversion) hiddenFromShowQueries() {}
+
 // StatementType implements the Statement interface.
 func (*AlterDatabaseOwner) StatementType() StatementType { return DDL }
 
@@ -1034,6 +1042,7 @@ func (*ValuesClause) StatementTag() string { return "VALUES" }
 
 func (n *AlterAggregate) String() string                 { return AsString(n) }
 func (n *AlterCollation) String() string                 { return AsString(n) }
+func (n *AlterConversion) String() string                { return AsString(n) }
 func (n *AlterIndex) String() string                     { return AsString(n) }
 func (n *AlterDatabaseOwner) String() string             { return AsString(n) }
 func (n *AlterSchema) String() string                    { return AsString(n) }

testing/generation/command_docs/output/alter_conversion_test.go

@@ -18,12 +18,12 @@ import "testing"
 
 func TestAlterConversion(t *testing.T) {
 	tests := []QueryParses{
-		Unimplemented("ALTER CONVERSION name RENAME TO new_name"),
-		Unimplemented("ALTER CONVERSION name OWNER TO new_owner"),
-		Unimplemented("ALTER CONVERSION name OWNER TO CURRENT_ROLE"),
-		Unimplemented("ALTER CONVERSION name OWNER TO CURRENT_USER"),
-		Unimplemented("ALTER CONVERSION name OWNER TO SESSION_USER"),
-		Unimplemented("ALTER CONVERSION name SET SCHEMA new_schema"),
+		Parses("ALTER CONVERSION name RENAME TO new_name"),
+		Parses("ALTER CONVERSION name OWNER TO new_owner"),
+		Parses("ALTER CONVERSION name OWNER TO CURRENT_ROLE"),
+		Parses("ALTER CONVERSION name OWNER TO CURRENT_USER"),
+		Parses("ALTER CONVERSION name OWNER TO SESSION_USER"),
+		Parses("ALTER CONVERSION name SET SCHEMA new_schema"),
 	}
 	RunTests(t, tests)
 }