From 4fa8340572ad67d1435e06392ad9079d2ee2af42 Mon Sep 17 00:00:00 2001
From: Ruihang Xia <waynestxia@gmail.com>
Date: Wed, 12 Jul 2023 14:41:31 +0800
Subject: [PATCH] feat: support desc [table] <table_name> (#1944)

* feat: support desc [table]

Signed-off-by: Ruihang Xia <waynestxia@gmail.com>

* refine style

Signed-off-by: Ruihang Xia <waynestxia@gmail.com>

---------

Signed-off-by: Ruihang Xia <waynestxia@gmail.com>
---
 src/sql/src/parser.rs                         | 20 ++++++-
 .../common/describe/describe_table.result     | 58 +++++++++++++++++++
 .../common/describe/describe_table.sql        | 17 ++++++
 3 files changed, 92 insertions(+), 3 deletions(-)
 create mode 100644 tests/cases/standalone/common/describe/describe_table.result
 create mode 100644 tests/cases/standalone/common/describe/describe_table.sql

diff --git a/src/sql/src/parser.rs b/src/sql/src/parser.rs
index eb8fc4ac30..4da3328f8b 100644
--- a/src/sql/src/parser.rs
+++ b/src/sql/src/parser.rs
@@ -261,10 +261,8 @@ impl<'a> ParserContext<'a> {
     fn parse_describe(&mut self) -> Result<Statement> {
         if self.matches_keyword(Keyword::TABLE) {
             let _ = self.parser.next_token();
-            self.parse_describe_table()
-        } else {
-            self.unsupported(self.peek_token_as_string())
         }
+        self.parse_describe_table()
     }
 
     fn parse_describe_table(&mut self) -> Result<Statement> {
@@ -677,4 +675,20 @@ mod tests {
             ParserContext::parse_function("current_timestamp()", &GreptimeDbDialect {}).unwrap();
         assert!(matches!(expr, Expr::Function(_)));
     }
+
+    fn assert_describe_table(sql: &str) {
+        let stmt = ParserContext::create_with_dialect(sql, &GreptimeDbDialect {})
+            .unwrap()
+            .pop()
+            .unwrap();
+        assert!(matches!(stmt, Statement::DescribeTable(_)))
+    }
+
+    #[test]
+    fn test_parse_describe_table() {
+        assert_describe_table("desc table t;");
+        assert_describe_table("describe table t;");
+        assert_describe_table("desc t;");
+        assert_describe_table("describe t;");
+    }
 }
diff --git a/tests/cases/standalone/common/describe/describe_table.result b/tests/cases/standalone/common/describe/describe_table.result
new file mode 100644
index 0000000000..e23a6f836e
--- /dev/null
+++ b/tests/cases/standalone/common/describe/describe_table.result
@@ -0,0 +1,58 @@
+create table host_load1(
+    ts timestamp time index,
+    collector string,
+    host string,
+    val double,
+    primary key (collector, host)
+);
+
+Affected Rows: 0
+
+describe table host_load1;
+
++-----------+----------------------+------+---------+---------------+
+| Field     | Type                 | Null | Default | Semantic Type |
++-----------+----------------------+------+---------+---------------+
+| ts        | TimestampMillisecond | NO   |         | TIME INDEX    |
+| collector | String               | YES  |         | PRIMARY KEY   |
+| host      | String               | YES  |         | PRIMARY KEY   |
+| val       | Float64              | YES  |         | FIELD         |
++-----------+----------------------+------+---------+---------------+
+
+describe host_load1;
+
++-----------+----------------------+------+---------+---------------+
+| Field     | Type                 | Null | Default | Semantic Type |
++-----------+----------------------+------+---------+---------------+
+| ts        | TimestampMillisecond | NO   |         | TIME INDEX    |
+| collector | String               | YES  |         | PRIMARY KEY   |
+| host      | String               | YES  |         | PRIMARY KEY   |
+| val       | Float64              | YES  |         | FIELD         |
++-----------+----------------------+------+---------+---------------+
+
+desc table host_load1;
+
++-----------+----------------------+------+---------+---------------+
+| Field     | Type                 | Null | Default | Semantic Type |
++-----------+----------------------+------+---------+---------------+
+| ts        | TimestampMillisecond | NO   |         | TIME INDEX    |
+| collector | String               | YES  |         | PRIMARY KEY   |
+| host      | String               | YES  |         | PRIMARY KEY   |
+| val       | Float64              | YES  |         | FIELD         |
++-----------+----------------------+------+---------+---------------+
+
+desc host_load1;
+
++-----------+----------------------+------+---------+---------------+
+| Field     | Type                 | Null | Default | Semantic Type |
++-----------+----------------------+------+---------+---------------+
+| ts        | TimestampMillisecond | NO   |         | TIME INDEX    |
+| collector | String               | YES  |         | PRIMARY KEY   |
+| host      | String               | YES  |         | PRIMARY KEY   |
+| val       | Float64              | YES  |         | FIELD         |
++-----------+----------------------+------+---------+---------------+
+
+drop table host_load1;
+
+Affected Rows: 1
+
diff --git a/tests/cases/standalone/common/describe/describe_table.sql b/tests/cases/standalone/common/describe/describe_table.sql
new file mode 100644
index 0000000000..49d7edda12
--- /dev/null
+++ b/tests/cases/standalone/common/describe/describe_table.sql
@@ -0,0 +1,17 @@
+create table host_load1(
+    ts timestamp time index,
+    collector string,
+    host string,
+    val double,
+    primary key (collector, host)
+);
+
+describe table host_load1;
+
+describe host_load1;
+
+desc table host_load1;
+
+desc host_load1;
+
+drop table host_load1;