Add support of DROP|CLEAR|MATERIALIZE PROJECTION syntax for ClickHouse (#1417)

src/ast/ddl.rs

@@ -57,6 +57,33 @@ pub enum AlterTableOperation {
         name: Ident,
         select: ProjectionSelect,
     },
+
+    /// `DROP PROJECTION [IF EXISTS] name`
+    ///
+    /// Note: this is a ClickHouse-specific operation.
+    /// Please refer to [ClickHouse](https://clickhouse.com/docs/en/sql-reference/statements/alter/projection#drop-projection)
+    DropProjection { if_exists: bool, name: Ident },
+
+    /// `MATERIALIZE PROJECTION [IF EXISTS] name [IN PARTITION partition_name]`
+    ///
+    ///  Note: this is a ClickHouse-specific operation.
+    /// Please refer to [ClickHouse](https://clickhouse.com/docs/en/sql-reference/statements/alter/projection#materialize-projection)
+    MaterializeProjection {
+        if_exists: bool,
+        name: Ident,
+        partition: Option<Ident>,
+    },
+
+    /// `CLEAR PROJECTION [IF EXISTS] name [IN PARTITION partition_name]`
+    ///
+    /// Note: this is a ClickHouse-specific operation.
+    /// Please refer to [ClickHouse](https://clickhouse.com/docs/en/sql-reference/statements/alter/projection#clear-projection)
+    ClearProjection {
+        if_exists: bool,
+        name: Ident,
+        partition: Option<Ident>,
+    },
+
     /// `DISABLE ROW LEVEL SECURITY`
     ///
     /// Note: this is a PostgreSQL-specific operation.
@@ -275,6 +302,43 @@ impl fmt::Display for AlterTableOperation {
                 }
                 write!(f, " {} ({})", name, query)
             }
+            AlterTableOperation::DropProjection { if_exists, name } => {
+                write!(f, "DROP PROJECTION")?;
+                if *if_exists {
+                    write!(f, " IF EXISTS")?;
+                }
+                write!(f, " {}", name)
+            }
+            AlterTableOperation::MaterializeProjection {
+                if_exists,
+                name,
+                partition,
+            } => {
+                write!(f, "MATERIALIZE PROJECTION")?;
+                if *if_exists {
+                    write!(f, " IF EXISTS")?;
+                }
+                write!(f, " {}", name)?;
+                if let Some(partition) = partition {
+                    write!(f, " IN PARTITION {}", partition)?;
+                }
+                Ok(())
+            }
+            AlterTableOperation::ClearProjection {
+                if_exists,
+                name,
+                partition,
+            } => {
+                write!(f, "CLEAR PROJECTION")?;
+                if *if_exists {
+                    write!(f, " IF EXISTS")?;
+                }
+                write!(f, " {}", name)?;
+                if let Some(partition) = partition {
+                    write!(f, " IN PARTITION {}", partition)?;
+                }
+                Ok(())
+            }
             AlterTableOperation::AlterColumn { column_name, op } => {
                 write!(f, "ALTER COLUMN {column_name} {op}")
             }

src/keywords.rs

@@ -153,6 +153,7 @@ define_keywords!(
     CHARSET,
     CHAR_LENGTH,
     CHECK,
+    CLEAR,
     CLOB,
     CLONE,
     CLOSE,
@@ -450,6 +451,7 @@ define_keywords!(
     MATCHES,
     MATCH_CONDITION,
     MATCH_RECOGNIZE,
+    MATERIALIZE,
     MATERIALIZED,
     MAX,
     MAXVALUE,

src/parser/mod.rs

@@ -6615,6 +6615,36 @@ impl<'a> Parser<'a> {
                     self.peek_token(),
                 );
             }
+        } else if self.parse_keywords(&[Keyword::CLEAR, Keyword::PROJECTION])
+            && dialect_of!(self is ClickHouseDialect|GenericDialect)
+        {
+            let if_exists = self.parse_keywords(&[Keyword::IF, Keyword::EXISTS]);
+            let name = self.parse_identifier(false)?;
+            let partition = if self.parse_keywords(&[Keyword::IN, Keyword::PARTITION]) {
+                Some(self.parse_identifier(false)?)
+            } else {
+                None
+            };
+            AlterTableOperation::ClearProjection {
+                if_exists,
+                name,
+                partition,
+            }
+        } else if self.parse_keywords(&[Keyword::MATERIALIZE, Keyword::PROJECTION])
+            && dialect_of!(self is ClickHouseDialect|GenericDialect)
+        {
+            let if_exists = self.parse_keywords(&[Keyword::IF, Keyword::EXISTS]);
+            let name = self.parse_identifier(false)?;
+            let partition = if self.parse_keywords(&[Keyword::IN, Keyword::PARTITION]) {
+                Some(self.parse_identifier(false)?)
+            } else {
+                None
+            };
+            AlterTableOperation::MaterializeProjection {
+                if_exists,
+                name,
+                partition,
+            }
         } else if self.parse_keyword(Keyword::DROP) {
             if self.parse_keywords(&[Keyword::IF, Keyword::EXISTS, Keyword::PARTITION]) {
                 self.expect_token(&Token::LParen)?;
@@ -6645,6 +6675,12 @@ impl<'a> Parser<'a> {
                 && dialect_of!(self is MySqlDialect | GenericDialect)
             {
                 AlterTableOperation::DropPrimaryKey
+            } else if self.parse_keyword(Keyword::PROJECTION)
+                && dialect_of!(self is ClickHouseDialect|GenericDialect)
+            {
+                let if_exists = self.parse_keywords(&[Keyword::IF, Keyword::EXISTS]);
+                let name = self.parse_identifier(false)?;
+                AlterTableOperation::DropProjection { if_exists, name }
             } else {
                 let _ = self.parse_keyword(Keyword::COLUMN); // [ COLUMN ]
                 let if_exists = self.parse_keywords(&[Keyword::IF, Keyword::EXISTS]);