Merge pull request #10726 from TCeason/ISSUE-10698

feat(query): support show columns query

Author: bohutang

src/query/ast/src/ast/format/ast_format.rs

@@ -1130,6 +1130,30 @@ impl<'ast> Visitor<'ast> for AstFormatVisitor {
         self.children.push(node);
     }
 
+    fn visit_show_columns(&mut self, stmt: &'ast ShowColumnsStmt) {
+        let mut children = Vec::new();
+        if let Some(database) = &stmt.database {
+            let database_name = format!("Database {}", database);
+            let database_format_ctx = AstFormatContext::new(database_name);
+            let database_node = FormatTreeNode::new(database_format_ctx);
+            children.push(database_node);
+        }
+
+        let table_name = format!("Table {}", &stmt.table);
+        let table_format_ctx = AstFormatContext::new(table_name);
+        let table_node = FormatTreeNode::new(table_format_ctx);
+        children.push(table_node);
+
+        if let Some(limit) = &stmt.limit {
+            self.visit_show_limit(limit);
+            children.push(self.children.pop().unwrap());
+        }
+        let name = "ShowColumns".to_string();
+        let format_ctx = AstFormatContext::with_children(name, children.len());
+        let node = FormatTreeNode::with_children(format_ctx, children);
+        self.children.push(node);
+    }
+
     fn visit_show_create_table(&mut self, stmt: &'ast ShowCreateTableStmt) {
         self.visit_table_ref(&stmt.catalog, &stmt.database, &stmt.table);
         let child = self.children.pop().unwrap();

src/query/ast/src/ast/statements/columns.rs

@@ -0,0 +1,52 @@
+// Copyright 2023 Datafuse Labs.
+//
+// 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.
+
+use std::fmt::Display;
+use std::fmt::Formatter;
+
+use crate::ast::Identifier;
+use crate::ast::ShowLimit;
+
+#[derive(Debug, Clone, PartialEq)] // Columns
+pub struct ShowColumnsStmt {
+    pub catalog: Option<Identifier>,
+    pub database: Option<Identifier>,
+    pub table: Identifier,
+    pub full: bool,
+    pub limit: Option<ShowLimit>,
+}
+
+impl Display for ShowColumnsStmt {
+    fn fmt(&self, f: &mut Formatter) -> std::fmt::Result {
+        write!(f, "SHOW")?;
+        if self.full {
+            write!(f, " FULL")?;
+        }
+        write!(f, " COLUMNS FROM {}", self.table)?;
+
+        if let Some(database) = &self.database {
+            write!(f, " FROM ")?;
+            if let Some(catalog) = &self.catalog {
+                write!(f, "{catalog}.",)?;
+            }
+            write!(f, "{database}")?;
+        }
+
+        if let Some(limit) = &self.limit {
+            write!(f, " {limit}")?;
+        }
+
+        Ok(())
+    }
+}

src/query/ast/src/ast/statements/mod.rs

@@ -14,6 +14,7 @@
 
 mod call;
 mod catalog;
+mod columns;
 mod copy;
 mod database;
 mod explain;
@@ -33,6 +34,7 @@ mod view;
 
 pub use call::*;
 pub use catalog::*;
+pub use columns::*;
 pub use copy::*;
 pub use database::*;
 pub use explain::*;

src/query/ast/src/ast/statements/statement.rs

@@ -114,6 +114,8 @@ pub enum Statement {
     OptimizeTable(OptimizeTableStmt),
     AnalyzeTable(AnalyzeTableStmt),
     ExistsTable(ExistsTableStmt),
+    // Columns
+    ShowColumns(ShowColumnsStmt),
 
     // Views
     CreateView(CreateViewStmt),
@@ -343,6 +345,7 @@ impl Display for Statement {
             Statement::AlterDatabase(stmt) => write!(f, "{stmt}")?,
             Statement::UseDatabase { database } => write!(f, "USE {database}")?,
             Statement::ShowTables(stmt) => write!(f, "{stmt}")?,
+            Statement::ShowColumns(stmt) => write!(f, "{stmt}")?,
             Statement::ShowCreateTable(stmt) => write!(f, "{stmt}")?,
             Statement::DescribeTable(stmt) => write!(f, "{stmt}")?,
             Statement::ShowTablesStatus(stmt) => write!(f, "{stmt}")?,

src/query/ast/src/parser/statement.rs

@@ -397,6 +397,25 @@ pub fn statement(i: Input) -> IResult<StatementMsg> {
             })
         },
     );
+    let show_columns = map(
+        rule! {
+            SHOW ~ FULL? ~ COLUMNS ~ ( FROM | IN ) ~ #ident ~ ((FROM | IN) ~ #period_separated_idents_1_to_2)? ~ #show_limit?
+        },
+        |(_, opt_full, _, _, table, ctl_db, limit)| {
+            let (catalog, database) = match ctl_db {
+                Some((_, (Some(c), d))) => (Some(c), Some(d)),
+                Some((_, (None, d))) => (None, Some(d)),
+                _ => (None, None),
+            };
+            Statement::ShowColumns(ShowColumnsStmt {
+                catalog,
+                database,
+                table,
+                full: opt_full.is_some(),
+                limit,
+            })
+        },
+    );
     let show_create_table = map(
         rule! {
             SHOW ~ CREATE ~ TABLE ~ #period_separated_idents_1_to_3
@@ -1094,6 +1113,7 @@ pub fn statement(i: Input) -> IResult<StatementMsg> {
         ),
         rule!(
             #show_tables : "`SHOW [FULL] TABLES [FROM <database>] [<show_limit>]`"
+            | #show_columns : "`SHOW [FULL] COLUMNS FROM <table> [FROM|IN <catalog>.<database>] [<show_limit>]`"
             | #show_create_table : "`SHOW CREATE TABLE [<database>.]<table>`"
             | #describe_table : "`DESCRIBE [<database>.]<table>`"
             | #show_fields : "`SHOW FIELDS FROM [<database>.]<table>`"

src/query/ast/src/parser/token.rs

@@ -315,6 +315,8 @@ pub enum TokenKind {
     CHAR,
     #[token("COLUMN", ignore(ascii_case))]
     COLUMN,
+    #[token("COLUMNS", ignore(ascii_case))]
+    COLUMNS,
     #[token("CHARACTER", ignore(ascii_case))]
     CHARACTER,
     #[token("CONFLICT", ignore(ascii_case))]

src/query/ast/src/visitors/visitor.rs

@@ -404,6 +404,8 @@ pub trait Visitor<'ast>: Sized {
 
     fn visit_show_tables(&mut self, _stmt: &'ast ShowTablesStmt) {}
 
+    fn visit_show_columns(&mut self, _stmt: &'ast ShowColumnsStmt) {}
+
     fn visit_show_create_table(&mut self, _stmt: &'ast ShowCreateTableStmt) {}
 
     fn visit_describe_table(&mut self, _stmt: &'ast DescribeTableStmt) {}

src/query/ast/src/visitors/visitor_mut.rs

@@ -410,6 +410,8 @@ pub trait VisitorMut: Sized {
 
     fn visit_show_tables(&mut self, _stmt: &mut ShowTablesStmt) {}
 
+    fn visit_show_columns(&mut self, _stmt: &mut ShowColumnsStmt) {}
+
     fn visit_show_create_table(&mut self, _stmt: &mut ShowCreateTableStmt) {}
 
     fn visit_describe_table(&mut self, _stmt: &mut DescribeTableStmt) {}

src/query/ast/src/visitors/walk.rs

@@ -344,6 +344,7 @@ pub fn walk_statement<'a, V: Visitor<'a>>(visitor: &mut V, statement: &'a Statem
         Statement::AlterDatabase(stmt) => visitor.visit_alter_database(stmt),
         Statement::UseDatabase { database } => visitor.visit_use_database(database),
         Statement::ShowTables(stmt) => visitor.visit_show_tables(stmt),
+        Statement::ShowColumns(stmt) => visitor.visit_show_columns(stmt),
         Statement::ShowCreateTable(stmt) => visitor.visit_show_create_table(stmt),
         Statement::DescribeTable(stmt) => visitor.visit_describe_table(stmt),
         Statement::ShowTablesStatus(stmt) => visitor.visit_show_tables_status(stmt),

src/query/ast/src/visitors/walk_mut.rs

@@ -344,6 +344,7 @@ pub fn walk_statement_mut<V: VisitorMut>(visitor: &mut V, statement: &mut Statem
         Statement::AlterDatabase(stmt) => visitor.visit_alter_database(stmt),
         Statement::UseDatabase { database } => visitor.visit_use_database(database),
         Statement::ShowTables(stmt) => visitor.visit_show_tables(stmt),
+        Statement::ShowColumns(stmt) => visitor.visit_show_columns(stmt),
         Statement::ShowCreateTable(stmt) => visitor.visit_show_create_table(stmt),
         Statement::DescribeTable(stmt) => visitor.visit_describe_table(stmt),
         Statement::ShowTablesStatus(stmt) => visitor.visit_show_tables_status(stmt),