drop schema support

core/rootvalue.go

@@ -17,6 +17,7 @@ package core
 import (
 	"bytes"
 	"context"
+	"fmt"
 	"slices"
 	"sort"
 	"strconv"
@@ -87,6 +88,62 @@ func (root *RootValue) CreateDatabaseSchema(ctx context.Context, dbSchema schema
 	return root.withStorage(r), nil
 }
 
+// DropDatabaseSchema implements the interface doltdb.RootValue.
+func (root *RootValue) DropDatabaseSchema(ctx context.Context, dbSchema schema.DatabaseSchema) (doltdb.RootValue, error) {
+	schemas, err := root.st.GetSchemas(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	found := false
+	schemaName := dbSchema.Name
+	for i, s := range schemas {
+		if strings.EqualFold(s.Name, dbSchema.Name) {
+			found = true
+			schemaName = s.Name
+			// remove this element in the slice
+			schemas = append(schemas[:i], schemas[i+1:]...)
+			break
+		}
+	}
+
+	if !found {
+		return nil, fmt.Errorf("No schema with the name %s exists", dbSchema.Name)
+	}
+
+	// Check for dangling objects in the schema and reject the drop if there are any
+	danglingObjects := false
+	root.IterRootObjects(ctx, func(name doltdb.TableName, table doltdb.RootObject) (stop bool, err error) {
+		if strings.EqualFold(name.Schema, dbSchema.Name) {
+			danglingObjects = true
+		}
+		return false, nil
+	})
+
+	// check the tables specifically in addition to root objects. This is just an extra paranoid step to avoid
+	// removing a schema that still has tables.
+	tableMap, err := root.getTableMap(ctx, schemaName)
+	if err != nil {
+		return nil, err
+	}
+
+	tableMap.Iter(ctx, func(name string, addr hash.Hash) (bool, error) {
+		danglingObjects = true
+		return true, nil
+	})
+
+	if danglingObjects {
+		return nil, fmt.Errorf("cannot drop schema %s because other objects depend on it", dbSchema.Name)
+	}
+
+	r, err := root.st.SetSchemas(ctx, schemas)
+	if err != nil {
+		return nil, err
+	}
+
+	return root.withStorage(r), nil
+}
+
 // validateSchemaForCreate returns an error if a schema with the name given cannot be created
 func validateSchemaForCreate(existingSchemas []schema.DatabaseSchema, dbSchema schema.DatabaseSchema) error {
 	if dbSchema.Name == "" {

go.mod

@@ -6,7 +6,7 @@ require (
 	github.com/PuerkitoBio/goquery v1.8.1
 	github.com/cockroachdb/apd/v2 v2.0.3-0.20200518165714-d020e156310a
 	github.com/cockroachdb/errors v1.7.5
-	github.com/dolthub/dolt/go v0.40.5-0.20260106173753-e3c81824fc90
+	github.com/dolthub/dolt/go v0.40.5-0.20260107002642-c6d39505a1d7
 	github.com/dolthub/eventsapi_schema v0.0.0-20250915094920-eadfd39051ca
 	github.com/dolthub/flatbuffers/v23 v23.3.3-dh.2
 	github.com/dolthub/go-mysql-server v0.20.1-0.20260106170317-759307e19edd

go.sum

@@ -228,8 +228,8 @@ github.com/dolthub/aws-sdk-go-ini-parser v0.0.0-20250305001723-2821c37f6c12 h1:I
 github.com/dolthub/aws-sdk-go-ini-parser v0.0.0-20250305001723-2821c37f6c12/go.mod h1:rN7X8BHwkjPcfMQQ2QTAq/xM3leUSGLfb+1Js7Y6TVo=
 github.com/dolthub/dolt-mcp v0.2.2 h1:bpROmam74n95uU4EA3BpOIVlTDT0pzeFMBwe/YRq2mI=
 github.com/dolthub/dolt-mcp v0.2.2/go.mod h1:S++DJ4QWTAXq+0TNzFa7Oq3IhoT456DJHwAINFAHgDQ=
-github.com/dolthub/dolt/go v0.40.5-0.20260106173753-e3c81824fc90 h1:lWOjwImXbtzaL34XjFYVCcnniJUt/jjGx9omvu4y5NU=
-github.com/dolthub/dolt/go v0.40.5-0.20260106173753-e3c81824fc90/go.mod h1:RrRSqn/03/yMFx3nxUyL1H8YkC60tJwhqq2UyuvIGNA=
+github.com/dolthub/dolt/go v0.40.5-0.20260107002642-c6d39505a1d7 h1:YNtBsIk6FyAmJ2Axf9whKRnH3zDfgyT8ovcxBPRlV6Y=
+github.com/dolthub/dolt/go v0.40.5-0.20260107002642-c6d39505a1d7/go.mod h1:1VZsnS76rDdgrOnzIiRwssoRXZVWHCC1F9gcWFYrlZA=
 github.com/dolthub/eventsapi_schema v0.0.0-20250915094920-eadfd39051ca h1:BGFz/0OlKIuC6qHIZQbvPapFvdAJkeEyGXWVgL5clmE=
 github.com/dolthub/eventsapi_schema v0.0.0-20250915094920-eadfd39051ca/go.mod h1:CoDLfgPqHyBtth0Cp+fi/CmC4R81zJNX4wPjShdZ+Bw=
 github.com/dolthub/flatbuffers/v23 v23.3.3-dh.2 h1:u3PMzfF8RkKd3lB9pZ2bfn0qEG+1Gms9599cr0REMww=

server/ast/drop_schema.go

@@ -17,6 +17,8 @@ package ast
 import (
 	vitess "github.com/dolthub/vitess/go/vt/sqlparser"
 
+	"github.com/dolthub/doltgresql/server/auth"
+
 	"github.com/dolthub/doltgresql/postgres/parser/sem/tree"
 )
 
@@ -27,5 +29,26 @@ func nodeDropSchema(ctx *Context, node *tree.DropSchema) (vitess.Statement, erro
 		return nil, nil
 	}
 
-	return NotYetSupportedError("DROP SCHEMA is not yet supported")
+	if len(node.Names) > 1 {
+		return NotYetSupportedError("DROP SCHEMA with multiple schema names is not yet supported.")
+	}
+
+	if node.DropBehavior == tree.DropCascade {
+		return NotYetSupportedError("DROP SCHEMA with CASCADE behavior is not yet supported.")
+	}
+
+	schemaName := node.Names[0]
+
+	return &vitess.DBDDL{
+		Action:           vitess.DropStr,
+		SchemaOrDatabase: "schema",
+		DBName:           schemaName,
+		CharsetCollate:   nil,
+		IfExists:         node.IfExists,
+		Auth: vitess.AuthInformation{
+			AuthType:    auth.AuthType_DELETE,
+			TargetType:  auth.AuthTargetType_SchemaIdentifiers,
+			TargetNames: []string{"", schemaName},
+		},
+	}, nil
 }

server/ast/no_op.go

@@ -53,5 +53,5 @@ func NotYetSupportedError(errorMsg string) (vitess.Statement, error) {
 		return NewNoOp(errorMsg), nil
 	}
 
-	return nil, errors.New(errorMsg)
+	return nil, errors.Errorf(errorMsg + " Please file an issue at https://github.com/dolthub/doltgresql/issues")
 }

testing/generation/command_docs/output/drop_schema_test.go

@@ -18,16 +18,16 @@ import "testing"
 
 func TestDropSchema(t *testing.T) {
 	tests := []QueryParses{
-		Parses("DROP SCHEMA name"),
-		Parses("DROP SCHEMA IF EXISTS name"),
+		Converts("DROP SCHEMA name"),
+		Converts("DROP SCHEMA IF EXISTS name"),
 		Parses("DROP SCHEMA name , name"),
 		Parses("DROP SCHEMA IF EXISTS name , name"),
 		Parses("DROP SCHEMA name CASCADE"),
 		Parses("DROP SCHEMA IF EXISTS name CASCADE"),
 		Parses("DROP SCHEMA name , name CASCADE"),
 		Parses("DROP SCHEMA IF EXISTS name , name CASCADE"),
-		Parses("DROP SCHEMA name RESTRICT"),
-		Parses("DROP SCHEMA IF EXISTS name RESTRICT"),
+		Converts("DROP SCHEMA name RESTRICT"),
+		Converts("DROP SCHEMA IF EXISTS name RESTRICT"),
 		Parses("DROP SCHEMA name , name RESTRICT"),
 		Parses("DROP SCHEMA IF EXISTS name , name RESTRICT"),
 	}

testing/go/auth_quick_test.go

@@ -104,13 +104,13 @@ func TestAuthQuick(t *testing.T) {
 				"CREATE SCHEMA newsch;",
 			},
 		},
-		{ // This isn't supported yet, but it is supposed to fail since tester is not an owner
+		{
 			Queries: []string{
 				"GRANT CREATE ON DATABASE postgres TO tester;",
 				"CREATE SCHEMA newsch;",
 				"DROP SCHEMA newsch;",
 			},
-			ExpectedErr: "not yet supported",
+			ExpectedErr: "permission denied for schema",
 		},
 		{
 			Queries: []string{

testing/go/schemas_test.go

@@ -869,11 +869,61 @@ var SchemaTests = []ScriptTest{
 			},
 		},
 	},
+	{
+		Name:  "drop schema",
+		Focus: true,
+		SetUpScript: []string{
+			"CREATE SCHEMA dropme",
+			`CREATE schema "hasTables"`,
+			"CREATE TABLE hasTables.t1 (pk BIGINT PRIMARY KEY, v1 BIGINT);",
+		},
+		Assertions: []ScriptTestAssertion{
+			{
+				Query: "Show schemas",
+				Expected: []sql.Row{
+					{"dolt"},
+					{"dropme"},
+					{"hasTables"},
+					{"pg_catalog"},
+					{"public"},
+					{"information_schema"},
+				},
+			},
+			{
+				Query:    "DROP SCHEMA dropme;",
+				Expected: []sql.Row{},
+			},
+			{
+				Query: "Show schemas",
+				Expected: []sql.Row{
+					{"dolt"},
+					{"hasTables"},
+					{"pg_catalog"},
+					{"public"},
+					{"information_schema"},
+				},
+			},
+			{
+				Query:       "DROP SCHEMA dropme;",
+				ExpectedErr: "database schema not found",
+			},
+			{
+				Query: "drop schema if exists dropme;",
+			},
+			{
+				Query:       "DROP SCHEMA hasTables;",
+				ExpectedErr: "cannot drop schema hastables because other objects depend on it",
+			},
+			{
+				Skip:  true, // not implemented yet
+				Query: "drop schema hasTables cascade;",
+			},
+		},
+	},
 	// More tests:
 	// * alter table statements, when they work better
 	// * AS OF (when supported)
 	// * revision qualifiers
-	// * drop schema
 	// * more statement types
 	// * INSERT INTO schema1 SELECT FROM schema2
 	// * Subqueries accessing different schemas in the same SELECT