Merge pull request #1901 from zhang2014/fix/ISSUES-117

ISSUES-117 add show create & exist temporary table

dbms/src/Interpreters/Context.cpp

@@ -673,6 +673,11 @@ bool Context::isDatabaseExist(const String & database_name) const
     return shared->databases.end() != shared->databases.find(db);
 }
 
+bool Context::isExternalTableExist(const String & table_name) const
+{
+    return external_tables.end() != external_tables.find(table_name);
+}
+
 
 void Context::assertTableExists(const String & database_name, const String & table_name) const
 {
@@ -733,7 +738,10 @@ Tables Context::getExternalTables() const
 {
     auto lock = getLock();
 
-    Tables res = external_tables;
+    Tables res;
+    for (auto & table : external_tables)
+        res[table.first] = table.second.first;
+
     if (session_context && session_context != this)
     {
         Tables buf = session_context->getExternalTables();
@@ -750,10 +758,11 @@ Tables Context::getExternalTables() const
 
 StoragePtr Context::tryGetExternalTable(const String & table_name) const
 {
-    auto it = external_tables.find(table_name);
-    if (external_tables.end() == it)
+    TableAndCreateASTs::const_iterator jt = external_tables.find(table_name);
+    if (external_tables.end() == jt)
         return StoragePtr();
-    return it->second;
+
+    return jt->second.first;
 }
 
 
@@ -807,12 +816,12 @@ StoragePtr Context::getTableImpl(const String & database_name, const String & ta
 }
 
 
-void Context::addExternalTable(const String & table_name, const StoragePtr & storage)
+void Context::addExternalTable(const String & table_name, const StoragePtr & storage, const ASTPtr & ast)
 {
     if (external_tables.end() != external_tables.find(table_name))
         throw Exception("Temporary table " + table_name + " already exists.", ErrorCodes::TABLE_ALREADY_EXISTS);
 
-    external_tables[table_name] = storage;
+    external_tables[table_name] = std::pair(storage, ast);
 
     if (process_list_elem)
     {
@@ -823,11 +832,12 @@ void Context::addExternalTable(const String & table_name, const StoragePtr & sto
 
 StoragePtr Context::tryRemoveExternalTable(const String & table_name)
 {
-    auto it = external_tables.find(table_name);
+    TableAndCreateASTs::const_iterator it = external_tables.find(table_name);
+
     if (external_tables.end() == it)
         return StoragePtr();
 
-    auto storage = it->second;
+    auto storage = it->second.first;
     external_tables.erase(it);
     return storage;
 }
@@ -917,6 +927,15 @@ ASTPtr Context::getCreateQuery(const String & database_name, const String & tabl
     return shared->databases[db]->getCreateQuery(*this, table_name);
 }
 
+ASTPtr Context::getCreateExternalQuery(const String & table_name) const
+{
+    TableAndCreateASTs::const_iterator jt = external_tables.find(table_name);
+    if (external_tables.end() == jt)
+        throw Exception("Temporary Table" + table_name + " doesn't exist", ErrorCodes::UNKNOWN_TABLE);
+
+    return jt->second.second;
+}
+
 
 Settings Context::getSettings() const
 {

dbms/src/Interpreters/Context.h

@@ -77,6 +77,9 @@ using DatabaseAndTableName = std::pair<String, String>;
 using ViewDependencies = std::map<DatabaseAndTableName, std::set<DatabaseAndTableName>>;
 using Dependencies = std::vector<DatabaseAndTableName>;
 
+using TableAndCreateAST = std::pair<StoragePtr, ASTPtr>;
+using TableAndCreateASTs = std::map<String, TableAndCreateAST>;
+
 
 /** A set of known objects that can be used in the query.
   * Consists of a shared part (always common to all sessions and queries)
@@ -103,7 +106,7 @@ private:
 
     String default_format;  /// Format, used when server formats data by itself and if query does not have FORMAT specification.
                             /// Thus, used in HTTP interface. If not specified - then some globally default format is used.
-    Tables external_tables;                 /// Temporary tables. Keyed by table name.
+    TableAndCreateASTs external_tables;     /// Temporary tables.
     Tables table_function_results;          /// Temporary tables obtained by execution of table functions. Keyed by AST tree id.
     Context * query_context = nullptr;
     Context * session_context = nullptr;    /// Session context or nullptr. Could be equal to this.
@@ -165,6 +168,7 @@ public:
     /// Checking the existence of the table/database. Database can be empty - in this case the current database is used.
     bool isTableExist(const String & database_name, const String & table_name) const;
     bool isDatabaseExist(const String & database_name) const;
+    bool isExternalTableExist(const String & table_name) const;
     void assertTableExists(const String & database_name, const String & table_name) const;
 
     /** The parameter check_database_access_rights exists to not check the permissions of the database again,
@@ -180,7 +184,7 @@ public:
     StoragePtr tryGetExternalTable(const String & table_name) const;
     StoragePtr getTable(const String & database_name, const String & table_name) const;
     StoragePtr tryGetTable(const String & database_name, const String & table_name) const;
-    void addExternalTable(const String & table_name, const StoragePtr & storage);
+    void addExternalTable(const String & table_name, const StoragePtr & storage, const ASTPtr & ast = {});
     StoragePtr tryRemoveExternalTable(const String & table_name);
 
     StoragePtr executeTableFunction(const ASTPtr & table_expression);
@@ -240,6 +244,7 @@ public:
 
     /// Get query for the CREATE table.
     ASTPtr getCreateQuery(const String & database_name, const String & table_name) const;
+    ASTPtr getCreateExternalQuery(const String & table_name) const;
 
     const DatabasePtr getDatabase(const String & database_name) const;
     DatabasePtr getDatabase(const String & database_name);

dbms/src/Interpreters/InterpreterCreateQuery.cpp

@@ -538,7 +538,7 @@ BlockIO InterpreterCreateQuery::createTable(ASTCreateQuery & create)
             false);
 
         if (create.is_temporary)
-            context.getSessionContext().addExternalTable(table_name, res);
+            context.getSessionContext().addExternalTable(table_name, res, query_ptr);
         else
             database->createTable(context, table_name, res, query_ptr);
     }

dbms/src/Interpreters/InterpreterExistsQuery.cpp

@@ -33,7 +33,7 @@ Block InterpreterExistsQuery::getSampleBlock()
 BlockInputStreamPtr InterpreterExistsQuery::executeImpl()
 {
     const ASTExistsQuery & ast = typeid_cast<const ASTExistsQuery &>(*query_ptr);
-    bool res = context.isTableExist(ast.database, ast.table);
+    bool res = ast.temporary ? context.isExternalTableExist(ast.table) : context.isTableExist(ast.database, ast.table);
 
     return std::make_shared<OneBlockInputStream>(Block{{
         ColumnUInt8::create(1, res),

dbms/src/Interpreters/InterpreterShowCreateQuery.cpp

@@ -11,10 +11,15 @@
 #include <Interpreters/Context.h>
 #include <Interpreters/InterpreterShowCreateQuery.h>
 
-
 namespace DB
 {
 
+namespace ErrorCodes
+{
+    extern const int SYNTAX_ERROR;
+    extern const int THERE_IS_NO_QUERY;
+}
+
 BlockIO InterpreterShowCreateQuery::execute()
 {
     BlockIO res;
@@ -36,8 +41,17 @@ BlockInputStreamPtr InterpreterShowCreateQuery::executeImpl()
 {
     const ASTShowCreateQuery & ast = typeid_cast<const ASTShowCreateQuery &>(*query_ptr);
 
+    if (ast.temporary && !ast.database.empty())
+        throw Exception("Temporary databases are not possible.", ErrorCodes::SYNTAX_ERROR);
+
+    ASTPtr create_query = (ast.temporary ? context.getCreateExternalQuery(ast.table) :
+                          context.getCreateQuery(ast.database, ast.table));
+
+    if (!create_query && ast.temporary)
+        throw Exception("Unable to show the create query of " + ast.table + ". Maybe it was created by the system.", ErrorCodes::THERE_IS_NO_QUERY);
+
     std::stringstream stream;
-    formatAST(*context.getCreateQuery(ast.database, ast.table), stream, false, true);
+    formatAST(*create_query, stream, false, true);
     String res = stream.str();
 
     MutableColumnPtr column = ColumnString::create();

dbms/src/Parsers/ASTQueryWithTableAndOutput.h

@@ -15,6 +15,7 @@ class ASTQueryWithTableAndOutput : public ASTQueryWithOutput
 public:
     String database;
     String table;
+    bool temporary{false};
 
 protected:
     void formatHelper(const FormatSettings & settings, const char * name) const

dbms/src/Parsers/ParserTablePropertiesQuery.cpp

@@ -14,6 +14,7 @@ namespace DB
 bool ParserTablePropertiesQuery::parseImpl(Pos & pos, ASTPtr & node, Expected & expected)
 {
     ParserKeyword s_exists("EXISTS");
+    ParserKeyword s_temporary("TEMPORARY");
     ParserKeyword s_describe("DESCRIBE");
     ParserKeyword s_desc("DESC");
     ParserKeyword s_show("SHOW");
@@ -42,6 +43,9 @@ bool ParserTablePropertiesQuery::parseImpl(Pos & pos, ASTPtr & node, Expected &
         return false;
     }
 
+    if (s_temporary.ignore(pos, expected))
+        query->temporary = true;
+
     s_table.ignore(pos, expected);
 
     if (!name_p.parse(pos, table, expected))

dbms/tests/queries/0_stateless/00564_show_tables_with_temporary.reference

@@ -1 +0,0 @@
-temp_tab

dbms/tests/queries/0_stateless/00564_show_tables_with_temporary.sql

@@ -1,4 +0,0 @@
-DROP TEMPORARY TABLE IF EXISTS temp_tab;
-CREATE TEMPORARY TABLE temp_tab (number UInt64);
-SHOW TEMPORARY TABLES LIKE 'temp_tab';
-DROP TEMPORARY TABLE temp_tab;

dbms/tests/queries/0_stateless/00564_temporary_table_management.reference

@@ -0,0 +1,4 @@
+1
+CREATE TEMPORARY TABLE temp_tab ( number UInt64) ENGINE = Memory
+temp_tab
+0

dbms/tests/queries/0_stateless/00564_temporary_table_management.sql

@@ -0,0 +1,7 @@
+DROP TEMPORARY TABLE IF EXISTS temp_tab;
+CREATE TEMPORARY TABLE temp_tab (number UInt64);
+EXISTS TEMPORARY TABLE temp_tab;
+SHOW CREATE TEMPORARY TABLE temp_tab;
+SHOW TEMPORARY TABLES LIKE 'temp_tab';
+DROP TEMPORARY TABLE temp_tab;
+EXISTS TEMPORARY TABLE temp_tab;

docs/en/query_language/queries.md

@@ -184,7 +184,7 @@ Deletes all tables inside the 'db' database, then deletes the 'db' database itse
 If `IF EXISTS` is specified, it doesn't return an error if the database doesn't exist.
 
 ```sql
-DROP TABLE [IF EXISTS] [db.]name [ON CLUSTER cluster]
+DROP [TEMPORARY] TABLE [IF EXISTS] [db.]name [ON CLUSTER cluster]
 ```
 
 Deletes the table.
@@ -452,7 +452,7 @@ See also the section "Formats".
 ## SHOW TABLES
 
 ```sql
-SHOW TABLES [FROM db] [LIKE 'pattern'] [INTO OUTFILE filename] [FORMAT format]
+SHOW [TEMPORARY] TABLES [FROM db] [LIKE 'pattern'] [INTO OUTFILE filename] [FORMAT format]
 ```
 
 Displays a list of tables
@@ -499,7 +499,7 @@ watch -n1 "clickhouse-client --query='SHOW PROCESSLIST'"
 ## SHOW CREATE TABLE
 
 ```sql
-SHOW CREATE TABLE [db.]table [INTO OUTFILE filename] [FORMAT format]
+SHOW CREATE [TEMPORARY] TABLE [db.]table [INTO OUTFILE filename] [FORMAT format]
 ```
 
 Returns a single `String`-type 'statement' column, which contains a single value – the `CREATE` query used for creating the specified table.
@@ -517,7 +517,7 @@ Nested data structures are output in "expanded" format. Each column is shown sep
 ## EXISTS
 
 ```sql
-EXISTS TABLE [db.]name [INTO OUTFILE filename] [FORMAT format]
+EXISTS [TEMPORARY] TABLE [db.]name [INTO OUTFILE filename] [FORMAT format]
 ```
 
 Returns a single `UInt8`-type column, which contains the single value `0` if the table or database doesn't exist, or `1` if the table exists in the specified database.