From 624769845abf1dacee1be422e88ea842de0e713d Mon Sep 17 00:00:00 2001
From: Jefffrey <22608443+Jefffrey@users.noreply.github.com>
Date: Mon, 1 Jan 2024 20:33:25 +1100
Subject: [PATCH] Remove DescribeTableStmt in parser in favour of existing
 functionality from sqlparser-rs

---
 datafusion/core/src/execution/context/mod.rs |  3 ---
 datafusion/sql/src/parser.rs                 | 22 --------------------
 datafusion/sql/src/statement.rs              | 15 +++++++------
 3 files changed, 7 insertions(+), 33 deletions(-)

diff --git a/datafusion/core/src/execution/context/mod.rs b/datafusion/core/src/execution/context/mod.rs
index 8916fa814a4a..c51f2d132aad 100644
--- a/datafusion/core/src/execution/context/mod.rs
+++ b/datafusion/core/src/execution/context/mod.rs
@@ -1621,9 +1621,6 @@ impl SessionState {
                         .0
                         .insert(ObjectName(vec![Ident::from(table.name.as_str())]));
                 }
-                DFStatement::DescribeTableStmt(table) => {
-                    visitor.insert(&table.table_name)
-                }
                 DFStatement::CopyTo(CopyToStatement {
                     source,
                     target: _,
diff --git a/datafusion/sql/src/parser.rs b/datafusion/sql/src/parser.rs
index 9c104ff18a9b..dbd72ec5eb7a 100644
--- a/datafusion/sql/src/parser.rs
+++ b/datafusion/sql/src/parser.rs
@@ -213,13 +213,6 @@ impl fmt::Display for CreateExternalTable {
     }
 }
 
-/// DataFusion extension DDL for `DESCRIBE TABLE`
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub struct DescribeTableStmt {
-    /// Table name
-    pub table_name: ObjectName,
-}
-
 /// DataFusion SQL Statement.
 ///
 /// This can either be a [`Statement`] from [`sqlparser`] from a
@@ -233,8 +226,6 @@ pub enum Statement {
     Statement(Box<SQLStatement>),
     /// Extension: `CREATE EXTERNAL TABLE`
     CreateExternalTable(CreateExternalTable),
-    /// Extension: `DESCRIBE TABLE`
-    DescribeTableStmt(DescribeTableStmt),
     /// Extension: `COPY TO`
     CopyTo(CopyToStatement),
     /// EXPLAIN for extensions
@@ -246,7 +237,6 @@ impl fmt::Display for Statement {
         match self {
             Statement::Statement(stmt) => write!(f, "{stmt}"),
             Statement::CreateExternalTable(stmt) => write!(f, "{stmt}"),
-            Statement::DescribeTableStmt(_) => write!(f, "DESCRIBE TABLE ..."),
             Statement::CopyTo(stmt) => write!(f, "{stmt}"),
             Statement::Explain(stmt) => write!(f, "{stmt}"),
         }
@@ -345,10 +335,6 @@ impl<'a> DFParser<'a> {
                         self.parser.next_token(); // COPY
                         self.parse_copy()
                     }
-                    Keyword::DESCRIBE => {
-                        self.parser.next_token(); // DESCRIBE
-                        self.parse_describe()
-                    }
                     Keyword::EXPLAIN => {
                         // (TODO parse all supported statements)
                         self.parser.next_token(); // EXPLAIN
@@ -371,14 +357,6 @@ impl<'a> DFParser<'a> {
         }
     }
 
-    /// Parse a SQL `DESCRIBE` statement
-    pub fn parse_describe(&mut self) -> Result<Statement, ParserError> {
-        let table_name = self.parser.parse_object_name()?;
-        Ok(Statement::DescribeTableStmt(DescribeTableStmt {
-            table_name,
-        }))
-    }
-
     /// Parse a SQL `COPY TO` statement
     pub fn parse_copy(&mut self) -> Result<Statement, ParserError> {
         // parse as a query
diff --git a/datafusion/sql/src/statement.rs b/datafusion/sql/src/statement.rs
index 12083554f093..1056a457bfd3 100644
--- a/datafusion/sql/src/statement.rs
+++ b/datafusion/sql/src/statement.rs
@@ -19,8 +19,8 @@ use std::collections::{BTreeMap, HashMap, HashSet};
 use std::sync::Arc;
 
 use crate::parser::{
-    CopyToSource, CopyToStatement, CreateExternalTable, DFParser, DescribeTableStmt,
-    ExplainStatement, LexOrdering, Statement as DFStatement,
+    CopyToSource, CopyToStatement, CreateExternalTable, DFParser, ExplainStatement,
+    LexOrdering, Statement as DFStatement,
 };
 use crate::planner::{
     object_name_to_qualifier, ContextProvider, PlannerContext, SqlToRel,
@@ -136,7 +136,6 @@ impl<'a, S: ContextProvider> SqlToRel<'a, S> {
         match statement {
             DFStatement::CreateExternalTable(s) => self.external_table_to_plan(s),
             DFStatement::Statement(s) => self.sql_statement_to_plan(*s),
-            DFStatement::DescribeTableStmt(s) => self.describe_table_to_plan(s),
             DFStatement::CopyTo(s) => self.copy_to_plan(s),
             DFStatement::Explain(ExplainStatement {
                 verbose,
@@ -170,6 +169,10 @@ impl<'a, S: ContextProvider> SqlToRel<'a, S> {
     ) -> Result<LogicalPlan> {
         let sql = Some(statement.to_string());
         match statement {
+            Statement::ExplainTable {
+                describe_alias: true, // only parse 'DESCRIBE table_name' and not 'EXPLAIN table_name'
+                table_name,
+            } => self.describe_table_to_plan(table_name),
             Statement::Explain {
                 verbose,
                 statement,
@@ -629,11 +632,7 @@ impl<'a, S: ContextProvider> SqlToRel<'a, S> {
         }
     }
 
-    fn describe_table_to_plan(
-        &self,
-        statement: DescribeTableStmt,
-    ) -> Result<LogicalPlan> {
-        let DescribeTableStmt { table_name } = statement;
+    fn describe_table_to_plan(&self, table_name: ObjectName) -> Result<LogicalPlan> {
         let table_ref = self.object_name_to_table_reference(table_name)?;
 
         let table_source = self.context_provider.get_table_source(table_ref)?;