feat: support show views statement (#4360)

This commit enables show view statement which will display a list of views
names.

src/frontend/src/instance.rs

@@ -506,6 +506,9 @@ pub fn check_permission(
         Statement::ShowIndex(stmt) => {
             validate_db_permission!(stmt, query_ctx);
         }
+        Statement::ShowViews(stmt) => {
+            validate_db_permission!(stmt, query_ctx);
+        }
         Statement::ShowStatus(_stmt) => {}
         Statement::DescribeTable(stmt) => {
             validate_param(stmt.name(), query_ctx)?;

src/operator/src/statement.rs

@@ -136,6 +136,8 @@ impl StatementExecutor {
 
             Statement::ShowCharset(kind) => self.show_charset(kind, query_ctx).await,
 
+            Statement::ShowViews(stmt) => self.show_views(stmt, query_ctx).await,
+
             Statement::Copy(sql::statements::copy::Copy::CopyTable(stmt)) => {
                 let req = to_copy_table_request(stmt, query_ctx.clone())?;
                 match req.direction {

src/operator/src/statement/show.rs

@@ -24,7 +24,7 @@ use sql::ast::Ident;
 use sql::statements::create::Partitions;
 use sql::statements::show::{
     ShowColumns, ShowCreateFlow, ShowCreateView, ShowDatabases, ShowIndex, ShowKind,
-    ShowTableStatus, ShowTables, ShowVariables,
+    ShowTableStatus, ShowTables, ShowVariables, ShowViews,
 };
 use table::metadata::TableType;
 use table::table_name::TableName;
@@ -152,6 +152,17 @@ impl StatementExecutor {
             .context(error::ExecuteStatementSnafu)
     }
 
+    #[tracing::instrument(skip_all)]
+    pub(super) async fn show_views(
+        &self,
+        stmt: ShowViews,
+        query_ctx: QueryContextRef,
+    ) -> Result<Output> {
+        query::sql::show_views(stmt, &self.query_engine, &self.catalog_manager, query_ctx)
+            .await
+            .context(ExecuteStatementSnafu)
+    }
+
     #[tracing::instrument(skip_all)]
     pub async fn show_create_flow(
         &self,

src/query/src/sql.rs

@@ -19,7 +19,7 @@ use std::sync::Arc;
 
 use catalog::information_schema::{
     columns, key_column_usage, schemata, tables, CHARACTER_SETS, COLLATIONS, COLUMNS,
-    KEY_COLUMN_USAGE, SCHEMATA, TABLES,
+    KEY_COLUMN_USAGE, SCHEMATA, TABLES, VIEWS,
 };
 use catalog::CatalogManagerRef;
 use common_catalog::consts::{
@@ -55,6 +55,7 @@ use sql::parser::ParserContext;
 use sql::statements::create::{CreateFlow, CreateView, Partitions};
 use sql::statements::show::{
     ShowColumns, ShowDatabases, ShowIndex, ShowKind, ShowTableStatus, ShowTables, ShowVariables,
+    ShowViews,
 };
 use sql::statements::statement::Statement;
 use sqlparser::ast::ObjectName;
@@ -69,6 +70,7 @@ use crate::QueryEngineRef;
 const SCHEMAS_COLUMN: &str = "Database";
 const OPTIONS_COLUMN: &str = "Options";
 const TABLES_COLUMN: &str = "Tables";
+const VIEWS_COLUMN: &str = "Views";
 const FIELD_COLUMN: &str = "Field";
 const TABLE_TYPE_COLUMN: &str = "Table_type";
 const COLUMN_NAME_COLUMN: &str = "Column";
@@ -725,6 +727,42 @@ pub fn show_create_view(
     Ok(Output::new_with_record_batches(records))
 }
 
+/// Execute [`ShowViews`] statement and return the [`Output`] if success.
+pub async fn show_views(
+    stmt: ShowViews,
+    query_engine: &QueryEngineRef,
+    catalog_manager: &CatalogManagerRef,
+    query_ctx: QueryContextRef,
+) -> Result<Output> {
+    let schema_name = if let Some(database) = stmt.database {
+        database
+    } else {
+        query_ctx.current_schema()
+    };
+
+    let projects = vec![(tables::TABLE_NAME, VIEWS_COLUMN)];
+    let filters = vec![
+        col(tables::TABLE_SCHEMA).eq(lit(schema_name.clone())),
+        col(tables::TABLE_CATALOG).eq(lit(query_ctx.current_catalog())),
+    ];
+    let like_field = Some(tables::TABLE_NAME);
+    let sort = vec![col(tables::TABLE_NAME).sort(true, true)];
+
+    query_from_information_schema_table(
+        query_engine,
+        catalog_manager,
+        query_ctx,
+        VIEWS,
+        vec![],
+        projects,
+        filters,
+        like_field,
+        sort,
+        stmt.kind,
+    )
+    .await
+}
+
 pub fn show_create_flow(
     flow_name: ObjectName,
     flow_val: FlowInfoValue,

src/sql/src/parsers/show_parser.rs

@@ -22,7 +22,7 @@ use crate::error::{
 use crate::parser::ParserContext;
 use crate::statements::show::{
     ShowColumns, ShowCreateFlow, ShowCreateTable, ShowCreateView, ShowDatabases, ShowIndex,
-    ShowKind, ShowStatus, ShowTableStatus, ShowTables, ShowVariables,
+    ShowKind, ShowStatus, ShowTableStatus, ShowTables, ShowVariables, ShowViews,
 };
 use crate::statements::statement::Statement;
 
@@ -44,6 +44,8 @@ impl<'a> ParserContext<'a> {
             } else {
                 self.unsupported(self.peek_token_as_string())
             }
+        } else if self.consume_token("VIEWS") {
+            self.parse_show_views()
         } else if self.matches_keyword(Keyword::CHARSET) {
             self.parser.next_token();
             Ok(Statement::ShowCharset(self.parse_show_kind()?))
@@ -430,6 +432,28 @@ impl<'a> ParserContext<'a> {
             _ => self.unsupported(self.peek_token_as_string()),
         }
     }
+
+    fn parse_show_views(&mut self) -> Result<Statement> {
+        let database = match self.parser.peek_token().token {
+            Token::EOF | Token::SemiColon => {
+                return Ok(Statement::ShowViews(ShowViews {
+                    kind: ShowKind::All,
+                    database: None,
+                }));
+            }
+
+            // SHOW VIEWS [in | FROM] [DATABASE]
+            Token::Word(w) => match w.keyword {
+                Keyword::IN | Keyword::FROM => self.parse_db_name()?,
+                _ => None,
+            },
+            _ => None,
+        };
+
+        let kind = self.parse_show_kind()?;
+
+        Ok(Statement::ShowViews(ShowViews { kind, database }))
+    }
 }
 
 #[cfg(test)]
@@ -942,4 +966,38 @@ mod tests {
         );
         assert_eq!(sql, stmts[0].to_string());
     }
+
+    #[test]
+    pub fn test_show_views() {
+        let sql = "SHOW VIEWS";
+        let result =
+            ParserContext::create_with_dialect(sql, &GreptimeDbDialect {}, ParseOptions::default());
+        let stmts = result.unwrap();
+        assert_eq!(1, stmts.len());
+        assert_eq!(
+            stmts[0],
+            Statement::ShowViews(ShowViews {
+                kind: ShowKind::All,
+                database: None,
+            })
+        );
+        assert_eq!(sql, stmts[0].to_string());
+    }
+
+    #[test]
+    pub fn test_show_views_in_db() {
+        let sql = "SHOW VIEWS IN d1";
+        let result =
+            ParserContext::create_with_dialect(sql, &GreptimeDbDialect {}, ParseOptions::default());
+        let stmts = result.unwrap();
+        assert_eq!(1, stmts.len());
+        assert_eq!(
+            stmts[0],
+            Statement::ShowViews(ShowViews {
+                kind: ShowKind::All,
+                database: Some("d1".to_string()),
+            })
+        );
+        assert_eq!(sql, stmts[0].to_string());
+    }
 }

src/sql/src/statements/show.rs

@@ -200,6 +200,25 @@ impl Display for ShowCreateView {
     }
 }
 
+/// SQL structure for `SHOW VIEWS`.
+#[derive(Debug, Clone, PartialEq, Eq, Visit, VisitMut)]
+pub struct ShowViews {
+    pub kind: ShowKind,
+    pub database: Option<String>,
+}
+
+impl Display for ShowViews {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "SHOW VIEWS")?;
+        if let Some(database) = &self.database {
+            write!(f, " IN {database}")?;
+        }
+        format_kind!(self, f);
+
+        Ok(())
+    }
+}
+
 /// SQL structure for `SHOW VARIABLES xxx`.
 #[derive(Debug, Clone, PartialEq, Eq, Visit, VisitMut)]
 pub struct ShowVariables {
@@ -473,6 +492,49 @@ SHOW FULL TABLES"#,
         }
     }
 
+    #[test]
+    fn test_display_show_views() {
+        let sql = r"show views in d1;";
+        let stmts: Vec<Statement> =
+            ParserContext::create_with_dialect(sql, &GreptimeDbDialect {}, ParseOptions::default())
+                .unwrap();
+        assert_eq!(1, stmts.len());
+        assert_matches!(&stmts[0], Statement::ShowViews { .. });
+        match &stmts[0] {
+            Statement::ShowViews(show) => {
+                let new_sql = format!("\n{}", show);
+                assert_eq!(
+                    r#"
+SHOW VIEWS IN d1"#,
+                    &new_sql
+                );
+            }
+            _ => {
+                unreachable!();
+            }
+        }
+
+        let sql = r"show views;";
+        let stmts: Vec<Statement> =
+            ParserContext::create_with_dialect(sql, &GreptimeDbDialect {}, ParseOptions::default())
+                .unwrap();
+        assert_eq!(1, stmts.len());
+        assert_matches!(&stmts[0], Statement::ShowViews { .. });
+        match &stmts[0] {
+            Statement::ShowViews(show) => {
+                let new_sql = format!("\n{}", show);
+                assert_eq!(
+                    r#"
+SHOW VIEWS"#,
+                    &new_sql
+                );
+            }
+            _ => {
+                unreachable!();
+            }
+        }
+    }
+
     #[test]
     fn test_display_show_databases() {
         let sql = r"show databases;";

src/sql/src/statements/statement.rs

@@ -32,7 +32,7 @@ use crate::statements::query::Query;
 use crate::statements::set_variables::SetVariables;
 use crate::statements::show::{
     ShowColumns, ShowCreateFlow, ShowCreateTable, ShowCreateView, ShowDatabases, ShowIndex,
-    ShowKind, ShowStatus, ShowTableStatus, ShowTables, ShowVariables,
+    ShowKind, ShowStatus, ShowTableStatus, ShowTables, ShowVariables, ShowViews,
 };
 use crate::statements::tql::Tql;
 use crate::statements::truncate::TruncateTable;
@@ -91,6 +91,8 @@ pub enum Statement {
     ShowCreateView(ShowCreateView),
     // SHOW STATUS
     ShowStatus(ShowStatus),
+    // SHOW VIEWS
+    ShowViews(ShowViews),
     // DESCRIBE TABLE
     DescribeTable(DescribeTable),
     // EXPLAIN QUERY
@@ -132,6 +134,7 @@ impl Display for Statement {
             Statement::ShowCreateTable(s) => s.fmt(f),
             Statement::ShowCreateFlow(s) => s.fmt(f),
             Statement::ShowCreateView(s) => s.fmt(f),
+            Statement::ShowViews(s) => s.fmt(f),
             Statement::ShowStatus(s) => s.fmt(f),
             Statement::DescribeTable(s) => s.fmt(f),
             Statement::Explain(s) => s.fmt(f),

tests/cases/standalone/common/view/view.result

@@ -52,6 +52,14 @@ CREATE VIEW v1 AS SELECT * FROM dontexist;
 
 Error: 3000(PlanQuery), Failed to plan SQL: Error during planning: Table not found: greptime.public.dontexist
 
+SHOW VIEWS;
+
++-------+
+| Views |
++-------+
+| v1    |
++-------+
+
 DROP VIEW v1;
 
 Affected Rows: 0
@@ -81,3 +89,8 @@ SHOW TABLES;
 | numbers |
 +---------+
 
+SHOW VIEWS;
+
+++
+++
+

tests/cases/standalone/common/view/view.sql

@@ -30,6 +30,8 @@ INSERT INTO v1 VALUES (1);
 
 CREATE VIEW v1 AS SELECT * FROM dontexist;
 
+SHOW VIEWS;
+
 DROP VIEW v1;
 
 SELECT * FROM v1;
@@ -42,3 +44,5 @@ DROP VIEW IF EXISTS v2;
 DROP TABLE t1;
 
 SHOW TABLES;
+
+SHOW VIEWS;