[tarantool-patches] [PATCH v1 1/2] sql: introduce pragma sql_default_engine

[Kirill Shcherbatov <kshcherbatov@tarantool.org>]

Part of #2199.

@TarantoolBot document
Title: new pragma sql_default_engine
Now it is allowed to create vinyl spaces using special pragma
setting default engine for SQL requests.
Example:
\set language sql
pragma sql_default_engine='vinyl';
CREATE TABLE t3(a primary key,b,c);
---
 src/box/session.cc                   |  1 +
 src/box/session.h                    |  2 ++
 src/box/sql/build.c                  | 43 +++++++++++++++++++++++++++++++++++-
 src/box/sql/pragma.c                 |  8 +++++++
 src/box/sql/pragma.h                 |  6 +++++
 src/box/sql/sqliteInt.h              | 14 ++++++++++++
 test/sql-tap/gh-2367-pragma.test.lua | 14 +++++++++++-
 7 files changed, 86 insertions(+), 2 deletions(-)

diff --git a/src/box/session.cc b/src/box/session.cc
index e487280..810dd19 100644
--- a/src/box/session.cc
+++ b/src/box/session.cc
@@ -107,6 +107,7 @@ session_create(enum session_type type)
 	memset(&session->meta, 0, sizeof(session->meta));
 	session->type = type;
 	session->sql_flags = default_flags;
+	session->sql_default_engine = 0;
 
 	/* For on_connect triggers. */
 	credentials_init(&session->credentials, guest_user->auth_token,
diff --git a/src/box/session.h b/src/box/session.h
index 515c30a..df1dcbc 100644
--- a/src/box/session.h
+++ b/src/box/session.h
@@ -92,6 +92,8 @@ union session_meta {
 struct session {
 	/** Session id. */
 	uint64_t id;
+	/** SQL Tarantool Default storage engine. */
+	uint8_t sql_default_engine;
 	/** SQL Connection flag for current user session */
 	uint32_t sql_flags;
 	enum session_type type;
diff --git a/src/box/sql/build.c b/src/box/sql/build.c
index fff7c19..bcd4d31 100644
--- a/src/box/sql/build.c
+++ b/src/box/sql/build.c
@@ -493,6 +493,43 @@ sqlite3PrimaryKeyIndex(Table * pTab)
 }
 
 /**
+ * Get default engine name set in current_session.
+ * @retval engine name string.
+ */
+static const char *
+sql_default_engine_name(void)
+{
+	switch (current_session()->sql_default_engine) {
+		case SQL_STORAGE_ENGINE_MEMTX:
+			return "memtx";
+		case SQL_STORAGE_ENGINE_VINYL:
+			return "vinyl";
+		default:
+			unreachable();
+	}
+}
+
+int
+sql_default_engine_set(const char *engine_name)
+{
+	enum sql_storage_engine_t engine = 0;
+	size_t engine_name_len = strlen(engine_name);
+
+	if (engine_name_len == strlen("memtx") &&
+		sqlite3_stricmp(engine_name, "memtx") == 0) {
+		engine = SQL_STORAGE_ENGINE_MEMTX;
+	} else if (engine_name_len == strlen("vinyl") &&
+		sqlite3_stricmp(engine_name, "vinyl") == 0) {
+		engine = SQL_STORAGE_ENGINE_VINYL;
+	} else {
+		diag_set(ClientError, ER_NO_SUCH_ENGINE, engine_name);
+		return -1;
+	}
+	current_session()->sql_default_engine = engine;
+	return 0;
+}
+
+/**
  * Create and initialize a new SQL Table object.
  * All memory except table object itself is allocated on region.
  * @param parser SQL Parser object.
@@ -510,6 +547,9 @@ sql_table_new(Parse *parser, char *name)
 	if (table == NULL)
 		return NULL;
 
+	snprintf(table->def->engine_name, sizeof(table->def->engine_name), "%s",
+		 sql_default_engine_name());
+
 	table->iPKey = -1;
 	table->iAutoIncPKey = -1;
 	table->pSchema = db->pSchema;
@@ -1602,7 +1642,8 @@ createSpace(Parse * pParse, int iSpaceId, char *zStmt)
 	sqlite3VdbeAddOp4(v, OP_String8, 0, iFirstCol + 2 /* name */ , 0,
 			  sqlite3DbStrDup(pParse->db, p->def->name), P4_DYNAMIC);
 	sqlite3VdbeAddOp4(v, OP_String8, 0, iFirstCol + 3 /* engine */ , 0,
-			  "memtx", P4_STATIC);
+			  sqlite3DbStrDup(pParse->db, p->def->engine_name),
+			  P4_DYNAMIC);
 	sqlite3VdbeAddOp2(v, OP_Integer, p->def->field_count,
 			  iFirstCol + 4 /* field_count */ );
 	sqlite3VdbeAddOp4(v, OP_Blob, zOptsSz, iFirstCol + 5, MSGPACK_SUBTYPE,
diff --git a/src/box/sql/pragma.c b/src/box/sql/pragma.c
index 5fb29c7..90d1cc1 100644
--- a/src/box/sql/pragma.c
+++ b/src/box/sql/pragma.c
@@ -870,6 +870,14 @@ sqlite3Pragma(Parse * pParse, Token * pId,	/* First part of [schema.]id field */
 			}
 			break;
 		}
+		case PragTyp_DEFAULT_ENGINE: {
+			if (sql_default_engine_set(zRight) != 0) {
+				pParse->rc = SQL_TARANTOOL_ERROR;
+				pParse->nErr++;
+				goto pragma_out;
+			}
+			break;
+		}
 
 		/* *   PRAGMA busy_timeout *   PRAGMA busy_timeout = N *
 		 *
diff --git a/src/box/sql/pragma.h b/src/box/sql/pragma.h
index f966018..6e921d6 100644
--- a/src/box/sql/pragma.h
+++ b/src/box/sql/pragma.h
@@ -17,6 +17,7 @@
 #define PragTyp_STATS                         15
 #define PragTyp_TABLE_INFO                    17
 #define PragTyp_PARSER_TRACE                  24
+#define PragTyp_DEFAULT_ENGINE                25
 
 /* Property flags associated with various pragma. */
 #define PragFlg_NeedSchema 0x01	/* Force schema load before running */
@@ -247,6 +248,11 @@ static const PragmaName aPragmaName[] = {
 	 /* ColNames:  */ 0, 0,
 	 /* iArg:      */ SQLITE_ShortColNames},
 #endif
+	{ /* zName:     */ "sql_default_engine",
+	 /* ePragTyp:  */ PragTyp_DEFAULT_ENGINE,
+	 /* ePragFlg:  */ PragFlg_Result0 | PragFlg_NoColumns1,
+	 /* ColNames:  */ 0, 0,
+	 /* iArg:      */ 0},
 #if !defined(SQLITE_OMIT_FLAG_PRAGMAS)
 #if defined(SQLITE_DEBUG)
 	{ /* zName:     */ "sql_trace",
diff --git a/src/box/sql/sqliteInt.h b/src/box/sql/sqliteInt.h
index acda23d..8f5ef39 100644
--- a/src/box/sql/sqliteInt.h
+++ b/src/box/sql/sqliteInt.h
@@ -4560,6 +4560,20 @@ void sqlite3VdbeIOTraceSql(Vdbe *);
 #define sqlite3VdbeIOTraceSql(X)
 #endif
 
+enum sql_storage_engine_t {
+	SQL_STORAGE_ENGINE_MEMTX = 0,
+	SQL_STORAGE_ENGINE_VINYL = 1,
+};
+
+/**
+ * Set tarantool backend default engine for SQL interface.
+ * @param engine_name to set default.
+ * @retval -1 on error.
+ * @retval 0 on success.
+ */
+int
+sql_default_engine_set(const char *engine_name);
+
 /*
  * These routines are available for the mem2.c debugging memory allocator
  * only.  They are used to verify that different "types" of memory
diff --git a/test/sql-tap/gh-2367-pragma.test.lua b/test/sql-tap/gh-2367-pragma.test.lua
index a41a026..2ee8424 100755
--- a/test/sql-tap/gh-2367-pragma.test.lua
+++ b/test/sql-tap/gh-2367-pragma.test.lua
@@ -1,7 +1,7 @@
 #!/usr/bin/env tarantool
 test = require("sqltester")
 
-test:plan(1)
+test:plan(2)
 
 test:do_catchsql_test(
 	"pragma-1.3",
@@ -11,4 +11,16 @@ test:do_catchsql_test(
 		1, "no such pragma: KEK"
 	})
 
+---
+--- gh-2199: SQL default engine pragma
+---
+test:do_catchsql_test(
+	"pragma-2.1",
+	[[
+		pragma sql_default_engine='creepy';
+	]], {
+	1, "Space engine 'creepy' does not exist"
+})
+
+
 test:finish_test()
-- 
2.7.4