feat: Add ALTER SCHEMA support (apache#1980)

chenkovsky · ayman-sigma · commit e36f74391c1f · 2026-02-02T18:39:10.000-08:00
diff --git a/src/ast/ddl.rs b/src/ast/ddl.rs
@@ -3080,6 +3080,48 @@ impl fmt::Display for CreateConnector {
     }
 }
 
+/// An `ALTER SCHEMA` (`Statement::AlterSchema`) operation.
+///
+/// See [BigQuery](https://cloud.google.com/bigquery/docs/reference/standard-sql/data-definition-language#alter_schema_collate_statement)
+#[derive(Debug, Clone, PartialEq, PartialOrd, Eq, Ord, Hash)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "visitor", derive(Visit, VisitMut))]
+pub enum AlterSchemaOperation {
+    SetDefaultCollate {
+        collate: Expr,
+    },
+    AddReplica {
+        replica: Ident,
+        options: Option<Vec<SqlOption>>,
+    },
+    DropReplica {
+        replica: Ident,
+    },
+    SetOptionsParens {
+        options: Vec<SqlOption>,
+    },
+}
+
+impl fmt::Display for AlterSchemaOperation {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            AlterSchemaOperation::SetDefaultCollate { collate } => {
+                write!(f, "SET DEFAULT COLLATE {collate}")
+            }
+            AlterSchemaOperation::AddReplica { replica, options } => {
+                write!(f, "ADD REPLICA {replica}")?;
+                if let Some(options) = options {
+                    write!(f, " OPTIONS ({})", display_comma_separated(options))?;
+                }
+                Ok(())
+            }
+            AlterSchemaOperation::DropReplica { replica } => write!(f, "DROP REPLICA {replica}"),
+            AlterSchemaOperation::SetOptionsParens { options } => {
+                write!(f, "SET OPTIONS ({})", display_comma_separated(options))
+            }
+        }
+    }
+}
 /// `RenameTableNameKind` is the kind used in an `ALTER TABLE _ RENAME` statement.
 ///
 /// Note: [MySQL] is the only database that supports the AS keyword for this operation.
@@ -3102,6 +3144,30 @@ impl fmt::Display for RenameTableNameKind {
     }
 }
 
+#[derive(Debug, Clone, PartialEq, PartialOrd, Eq, Ord, Hash)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "visitor", derive(Visit, VisitMut))]
+pub struct AlterSchema {
+    pub name: ObjectName,
+    pub if_exists: bool,
+    pub operations: Vec<AlterSchemaOperation>,
+}
+
+impl fmt::Display for AlterSchema {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "ALTER SCHEMA ")?;
+        if self.if_exists {
+            write!(f, "IF EXISTS ")?;
+        }
+        write!(f, "{}", self.name)?;
+        for operation in &self.operations {
+            write!(f, " {operation}")?;
+        }
+
+        Ok(())
+    }
+}
+
 impl Spanned for RenameTableNameKind {
     fn span(&self) -> Span {
         match self {
diff --git a/src/ast/mod.rs b/src/ast/mod.rs
@@ -59,16 +59,17 @@ pub use self::dcl::{
 };
 pub use self::ddl::{
     AlterColumnOperation, AlterConnectorOwner, AlterIndexOperation, AlterPolicyOperation,
-    AlterTableAlgorithm, AlterTableLock, AlterTableOperation, AlterType, AlterTypeAddValue,
-    AlterTypeAddValuePosition, AlterTypeOperation, AlterTypeRename, AlterTypeRenameValue,
-    ClusteredBy, ColumnDef, ColumnOption, ColumnOptionDef, ColumnOptions, ColumnPolicy,
-    ColumnPolicyProperty, ConstraintCharacteristics, CreateConnector, CreateDomain, CreateFunction,
-    CreateIndex, CreateTable, Deduplicate, DeferrableInitial, DropBehavior, GeneratedAs,
-    GeneratedExpressionMode, IdentityParameters, IdentityProperty, IdentityPropertyFormatKind,
-    IdentityPropertyKind, IdentityPropertyOrder, IndexColumn, IndexOption, IndexType,
-    KeyOrIndexDisplay, NullsDistinctOption, Owner, Partition, ProcedureParam, ReferentialAction,
-    RenameTableNameKind, ReplicaIdentity, TableConstraint, TagsColumnOption,
-    UserDefinedTypeCompositeAttributeDef, UserDefinedTypeRepresentation, ViewColumnDef,
+    AlterSchema, AlterSchemaOperation, AlterTableAlgorithm, AlterTableLock, AlterTableOperation,
+    AlterType, AlterTypeAddValue, AlterTypeAddValuePosition, AlterTypeOperation, AlterTypeRename,
+    AlterTypeRenameValue, ClusteredBy, ColumnDef, ColumnOption, ColumnOptionDef, ColumnOptions,
+    ColumnPolicy, ColumnPolicyProperty, ConstraintCharacteristics, CreateConnector, CreateDomain,
+    CreateFunction, CreateIndex, CreateTable, Deduplicate, DeferrableInitial, DropBehavior,
+    GeneratedAs, GeneratedExpressionMode, IdentityParameters, IdentityProperty,
+    IdentityPropertyFormatKind, IdentityPropertyKind, IdentityPropertyOrder, IndexColumn,
+    IndexOption, IndexType, KeyOrIndexDisplay, NullsDistinctOption, Owner, Partition,
+    ProcedureParam, ReferentialAction, RenameTableNameKind, ReplicaIdentity, TableConstraint,
+    TagsColumnOption, UserDefinedTypeCompositeAttributeDef, UserDefinedTypeRepresentation,
+    ViewColumnDef,
 };
 pub use self::dml::{Delete, Insert};
 pub use self::operator::{BinaryOperator, UnaryOperator};
@@ -3417,6 +3418,11 @@ pub enum Statement {
         end_token: AttachedToken,
     },
     /// ```sql
+    /// ALTER SCHEMA
+    /// ```
+    /// See [BigQuery](https://cloud.google.com/bigquery/docs/reference/standard-sql/data-definition-language#alter_schema_collate_statement)
+    AlterSchema(AlterSchema),
+    /// ```sql
     /// ALTER INDEX
     /// ```
     AlterIndex {
@@ -6365,6 +6371,7 @@ impl fmt::Display for Statement {
             Statement::Remove(command) => write!(f, "REMOVE {command}"),
             Statement::ExportData(e) => write!(f, "{e}"),
             Statement::CreateUser(s) => write!(f, "{s}"),
+            Statement::AlterSchema(s) => write!(f, "{s}"),
         }
     }
 }
diff --git a/src/ast/spans.rs b/src/ast/spans.rs
@@ -15,7 +15,10 @@
 // specific language governing permissions and limitations
 // under the License.
 
-use crate::ast::{query::SelectItemQualifiedWildcardKind, ColumnOptions, ExportData, TypedString};
+use crate::ast::{
+    ddl::AlterSchema, query::SelectItemQualifiedWildcardKind, AlterSchemaOperation, ColumnOptions,
+    ExportData, TypedString,
+};
 use core::iter;
 
 use crate::tokenizer::Span;
@@ -548,6 +551,7 @@ impl Spanned for Statement {
                     .chain(connection.iter().map(|i| i.span())),
             ),
             Statement::CreateUser(..) => Span::empty(),
+            Statement::AlterSchema(s) => s.span(),
         }
     }
 }
@@ -2396,6 +2400,30 @@ impl Spanned for OpenStatement {
     }
 }
 
+impl Spanned for AlterSchemaOperation {
+    fn span(&self) -> Span {
+        match self {
+            AlterSchemaOperation::SetDefaultCollate { collate } => collate.span(),
+            AlterSchemaOperation::AddReplica { replica, options } => union_spans(
+                core::iter::once(replica.span)
+                    .chain(options.iter().flat_map(|i| i.iter().map(|i| i.span()))),
+            ),
+            AlterSchemaOperation::DropReplica { replica } => replica.span,
+            AlterSchemaOperation::SetOptionsParens { options } => {
+                union_spans(options.iter().map(|i| i.span()))
+            }
+        }
+    }
+}
+
+impl Spanned for AlterSchema {
+    fn span(&self) -> Span {
+        union_spans(
+            core::iter::once(self.name.span()).chain(self.operations.iter().map(|i| i.span())),
+        )
+    }
+}
+
 #[cfg(test)]
 pub mod tests {
     use crate::dialect::{Dialect, GenericDialect, SnowflakeDialect};
diff --git a/src/parser/mod.rs b/src/parser/mod.rs
@@ -9278,8 +9278,14 @@ impl<'a> Parser<'a> {
             Keyword::POLICY,
             Keyword::CONNECTOR,
             Keyword::ICEBERG,
+            Keyword::SCHEMA,
         ])?;
         match object_type {
+            Keyword::SCHEMA => {
+                self.prev_token();
+                self.prev_token();
+                self.parse_alter_schema()
+            }
             Keyword::VIEW => self.parse_alter_view(),
             Keyword::TYPE => self.parse_alter_type(),
             Keyword::TABLE => self.parse_alter_table(false),
@@ -9418,6 +9424,40 @@ impl<'a> Parser<'a> {
         }
     }
 
+    // Parse a [Statement::AlterSchema]
+    // ALTER SCHEMA [ IF EXISTS ] schema_name
+    pub fn parse_alter_schema(&mut self) -> Result<Statement, ParserError> {
+        self.expect_keywords(&[Keyword::ALTER, Keyword::SCHEMA])?;
+        let if_exists = self.parse_keywords(&[Keyword::IF, Keyword::EXISTS]);
+        let name = self.parse_object_name(false)?;
+        let operation = if self.parse_keywords(&[Keyword::SET, Keyword::OPTIONS]) {
+            self.prev_token();
+            let options = self.parse_options(Keyword::OPTIONS)?;
+            AlterSchemaOperation::SetOptionsParens { options }
+        } else if self.parse_keywords(&[Keyword::SET, Keyword::DEFAULT, Keyword::COLLATE]) {
+            let collate = self.parse_expr()?;
+            AlterSchemaOperation::SetDefaultCollate { collate }
+        } else if self.parse_keywords(&[Keyword::ADD, Keyword::REPLICA]) {
+            let replica = self.parse_identifier()?;
+            let options = if self.peek_keyword(Keyword::OPTIONS) {
+                Some(self.parse_options(Keyword::OPTIONS)?)
+            } else {
+                None
+            };
+            AlterSchemaOperation::AddReplica { replica, options }
+        } else if self.parse_keywords(&[Keyword::DROP, Keyword::REPLICA]) {
+            let replica = self.parse_identifier()?;
+            AlterSchemaOperation::DropReplica { replica }
+        } else {
+            return self.expected_ref("ALTER SCHEMA operation", self.peek_token_ref());
+        };
+        Ok(Statement::AlterSchema(AlterSchema {
+            name,
+            if_exists,
+            operations: vec![operation],
+        }))
+    }
+
     /// Parse a `CALL procedure_name(arg1, arg2, ...)`
     /// or `CALL procedure_name` statement
     pub fn parse_call(&mut self) -> Result<Statement, ParserError> {
diff --git a/tests/sqlparser_bigquery.rs b/tests/sqlparser_bigquery.rs
@@ -2825,3 +2825,15 @@ fn test_begin_transaction() {
 fn test_begin_statement() {
     bigquery().verified_stmt("BEGIN");
 }
+
+#[test]
+fn test_alter_schema() {
+    bigquery_and_generic().verified_stmt("ALTER SCHEMA mydataset SET DEFAULT COLLATE 'und:ci'");
+    bigquery_and_generic().verified_stmt("ALTER SCHEMA mydataset ADD REPLICA 'us'");
+    bigquery_and_generic()
+        .verified_stmt("ALTER SCHEMA mydataset ADD REPLICA 'us' OPTIONS (location = 'us')");
+    bigquery_and_generic().verified_stmt("ALTER SCHEMA mydataset DROP REPLICA 'us'");
+    bigquery_and_generic().verified_stmt("ALTER SCHEMA mydataset SET OPTIONS (location = 'us')");
+    bigquery_and_generic()
+        .verified_stmt("ALTER SCHEMA IF EXISTS mydataset SET OPTIONS (location = 'us')");
+}
