[tarantool-patches] [PATCH v2 1/3] 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.
This config is stored in user_session() and affect *only*
tables been created with SQL.
Example:
\set language sql
pragma sql_default_engine='vinyl';
CREATE TABLE t3(a primary key,b,c);
---
 src/box/schema_def.c                 |  5 +++++
 src/box/schema_def.h                 |  9 +++++++++
 src/box/session.cc                   |  1 +
 src/box/session.h                    |  2 ++
 src/box/sql/build.c                  |  6 +++++-
 src/box/sql/pragma.c                 | 28 ++++++++++++++++++++++++++++
 src/box/sql/pragma.h                 |  6 ++++++
 test/sql-tap/gh-2367-pragma.test.lua | 29 ++++++++++++++++++++++++++++-
 8 files changed, 84 insertions(+), 2 deletions(-)

diff --git a/src/box/schema_def.c b/src/box/schema_def.c
index 97c074a..cbfad47 100644
--- a/src/box/schema_def.c
+++ b/src/box/schema_def.c
@@ -30,6 +30,11 @@
  */
 #include "schema_def.h"
 
+const char *sql_storage_engine_strs[] = {
+	[SQL_STORAGE_ENGINE_MEMTX] = "memtx",
+	[SQL_STORAGE_ENGINE_VINYL] = "vinyl",
+};
+
 static const char *object_type_strs[] = {
 	/* [SC_UKNNOWN]         = */ "unknown",
 	/* [SC_UNIVERSE]        = */ "universe",
diff --git a/src/box/schema_def.h b/src/box/schema_def.h
index b9a5fa5..5ab4bb0 100644
--- a/src/box/schema_def.h
+++ b/src/box/schema_def.h
@@ -243,6 +243,15 @@ enum schema_object_type {
 	schema_object_type_MAX = 8
 };
 
+/** SQL Storage engine. */
+enum sql_storage_engine {
+    SQL_STORAGE_ENGINE_MEMTX = 0,
+    SQL_STORAGE_ENGINE_VINYL = 1,
+    sql_storage_engine_MAX = 2
+};
+
+extern const char *sql_storage_engine_strs[];
+
 enum schema_object_type
 schema_object_type(const char *name);
 
diff --git a/src/box/session.cc b/src/box/session.cc
index e487280..64714cd 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 = SQL_STORAGE_ENGINE_MEMTX;
 
 	/* 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 af90070..8c82503 100644
--- a/src/box/sql/build.c
+++ b/src/box/sql/build.c
@@ -510,6 +510,9 @@ sql_table_new(Parse *parser, char *name)
 	if (table == NULL)
 		return NULL;
 
+	strcpy(table->def->engine_name,
+	       sql_storage_engine_strs[current_session()->sql_default_engine]);
+
 	table->iPKey = -1;
 	table->iAutoIncPKey = -1;
 	table->pSchema = db->pSchema;
@@ -1602,7 +1605,8 @@ 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 be6a01c..7a25db6 100644
--- a/src/box/sql/pragma.c
+++ b/src/box/sql/pragma.c
@@ -235,6 +235,26 @@ printActivePragmas(struct session *user_session)
 	}
 }
 
+/**
+ * Set tarantool backend default engine for SQL interface.
+ * @param engine_name to set default.
+ * @retval -1 on error.
+ * @retval 0 on success.
+ */
+static int
+sql_default_engine_set(const char *engine_name)
+{
+	enum sql_storage_engine engine =
+		STR2ENUM(sql_storage_engine, engine_name);
+	if (engine == sql_storage_engine_MAX) {
+		diag_set(ClientError, ER_NO_SUCH_ENGINE, engine_name);
+		return -1;
+	}
+	current_session()->sql_default_engine = engine;
+	return 0;
+}
+
+
 /*
  * Process a pragma statement.
  *
@@ -868,6 +888,14 @@ 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 06b7eea..795c98c 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/test/sql-tap/gh-2367-pragma.test.lua b/test/sql-tap/gh-2367-pragma.test.lua
index a41a026..6d2e73d 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(4)
 
 test:do_catchsql_test(
 	"pragma-1.3",
@@ -11,4 +11,31 @@ 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:do_catchsql_test(
+	"pragma-2.2",
+	[[
+		pragma sql_default_engine='vinyl';
+	]], {
+	0
+})
+
+test:do_catchsql_test(
+	"pragma-2.3",
+	[[
+		pragma sql_default_engine='memtx';
+	]], {
+	0
+})
+
 test:finish_test()
-- 
2.7.4