Merge pull request #156 from sundy-li/show-queries

[plan] add show queries statement support

src/sql/plan_parser.rs

@@ -42,6 +42,16 @@ impl PlanParser {
             DFStatement::Statement(v) => self.sql_statement_to_plan(&v),
             DFStatement::Explain(v) => self.sql_explain_to_plan(&v),
             DFStatement::Create(v) => self.sql_create_to_plan(&v),
+
+            // TODO: support like and other filters in show queries
+            DFStatement::ShowTables(_) => self.build_from_sql(
+                format!(
+                    "SELECT name FROM system.tables where database = '{}'",
+                    self.ctx.get_default_db()?
+                )
+                .as_str(),
+            ),
+            DFStatement::ShowSettings(_) => self.build_from_sql("SELECT name FROM system.settings"),
         }
     }
 

src/sql/sql_parser.rs

@@ -57,6 +57,11 @@ pub struct FuseCreateTable {
     pub table_properties: Vec<SqlOption>,
 }
 
+#[derive(Debug, Clone, PartialEq)]
+pub struct FuseShowTables;
+#[derive(Debug, Clone, PartialEq)]
+pub struct FuseShowSettings;
+
 /// DataFusion extension DDL for `EXPLAIN` and `EXPLAIN VERBOSE`
 #[derive(Debug, Clone, PartialEq)]
 pub struct DFExplainPlan {
@@ -75,6 +80,8 @@ pub enum DFStatement {
     /// Extension: `EXPLAIN <SQL>`
     Explain(DFExplainPlan),
     Create(FuseCreateTable),
+    ShowTables(FuseShowTables),
+    ShowSettings(FuseShowSettings),
 }
 
 /// SQL Parser
@@ -153,6 +160,18 @@ impl<'a> DFParser<'a> {
                         self.parser.next_token();
                         self.parse_explain()
                     }
+
+                    Keyword::SHOW => {
+                        self.parser.next_token();
+
+                        if self.consume_token("TABLES") {
+                            Ok(DFStatement::ShowTables(FuseShowTables))
+                        } else if self.consume_token("SETTINGS") {
+                            Ok(DFStatement::ShowSettings(FuseShowSettings))
+                        } else {
+                            self.expected("tables or settings", self.parser.peek_token())
+                        }
+                    }
                     _ => {
                         // use the native parser
                         Ok(DFStatement::Statement(self.parser.parse_statement()?))

src/sql/sql_parser_test.rs

@@ -7,7 +7,7 @@ mod tests {
     use sqlparser::ast::{ColumnDef, DataType, Ident, ObjectName, SqlOption, Value};
     use sqlparser::parser::ParserError;
 
-    use crate::sql::sql_parser::FuseCreateTable;
+    use crate::sql::sql_parser::{FuseCreateTable, FuseShowSettings, FuseShowTables};
     use crate::sql::{DFParser, DFStatement, EngineType};
 
     fn expect_parse_ok(sql: &str, expected: DFStatement) -> Result<(), ParserError> {
@@ -98,4 +98,13 @@ mod tests {
 
         Ok(())
     }
+
+    #[test]
+    fn show_queries() -> Result<(), ParserError> {
+        // positive case
+        expect_parse_ok("SHOW TABLES", DFStatement::ShowTables(FuseShowTables))?;
+        expect_parse_ok("SHOW SETTINGS", DFStatement::ShowSettings(FuseShowSettings))?;
+
+        Ok(())
+    }
 }

tests/queries/0_stateless/00012_show_queries.reference

@@ -0,0 +1 @@
+t

tests/queries/0_stateless/00012_show_queries.sql

@@ -0,0 +1,2 @@
+CREATE TABLE t(c1 int) ENGINE = Null;
+SHOW TABLES;