[tarantool-patches] [PATCH v2 3/6] sql: Show currently set sql_default_engine

[imeevma@tarantool.org]

After this patch, "PRAGMA sql_default_engine" called without
arguments will return currently set sql_default_engine.

Part of #3832
---
 src/box/sql/pragma.c                 | 18 +++++++++++++-----
 test/sql-tap/gh-2367-pragma.test.lua | 35 +++++++++++++++++++++++++++--------
 2 files changed, 40 insertions(+), 13 deletions(-)

diff --git a/src/box/sql/pragma.c b/src/box/sql/pragma.c
index 1fe5b3e..f34e7b8 100644
--- a/src/box/sql/pragma.c
+++ b/src/box/sql/pragma.c
@@ -600,12 +600,20 @@ sqlite3Pragma(Parse * pParse, Token * pId,	/* First part of [schema.]id field */
 		}
 
 	case PragTyp_DEFAULT_ENGINE: {
-		if (sql_default_engine_set(zRight) != 0) {
-			pParse->rc = SQL_TARANTOOL_ERROR;
-			pParse->nErr++;
-			goto pragma_out;
+		if (zRight == NULL) {
+			const char *engine_name =
+				sql_storage_engine_strs[current_session()->
+							sql_default_engine];
+			sqlite3VdbeLoadString(v, 1, engine_name);
+			sqlite3VdbeAddOp2(v, OP_ResultRow, 1, 1);
+		} else {
+			if (sql_default_engine_set(zRight) != 0) {
+				pParse->rc = SQL_TARANTOOL_ERROR;
+				pParse->nErr++;
+				goto pragma_out;
+			}
+			sqlite3VdbeAddOp0(v, OP_Expire);
 		}
-		sqlite3VdbeAddOp0(v, OP_Expire);
 		break;
 	}
 
diff --git a/test/sql-tap/gh-2367-pragma.test.lua b/test/sql-tap/gh-2367-pragma.test.lua
index c0792c9..90ecd56 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(7)
+test:plan(8)
 
 test:do_catchsql_test(
 	"pragma-1.3",
@@ -41,25 +41,44 @@ test:do_catchsql_test(
 test:do_catchsql_test(
 	"pragma-2.4",
 	[[
-		pragma sql_default_engine;
+		pragma sql_default_engine 'memtx';
 	]], {
-	1, 'Illegal parameters, \'sql_default_engine\' was not specified'
+	1, 'near \"\'memtx\'\": syntax error'
 })
 
 test:do_catchsql_test(
 	"pragma-2.5",
 	[[
-		pragma sql_default_engine 'memtx';
+		pragma sql_default_engine 1;
 	]], {
-	1, 'near \"\'memtx\'\": syntax error'
+	1, 'near \"1\": syntax error'
 })
 
+--
+-- gh-3832: Some statements do not return column type
+--
+-- Check that "PRAGMA sql_default_engine" called without arguments
+-- returns currently set sql_default_engine.
 test:do_catchsql_test(
-	"pragma-2.5",
+	"pragma-3.1",
 	[[
-		pragma sql_default_engine 1;
+		pragma sql_default_engine='vinyl';
+		pragma sql_default_engine;
 	]], {
-	1, 'near \"1\": syntax error'
+	-- <pragma-3.1>
+	0, {'vinyl'}
+	-- <pragma-3.1>
+})
+
+test:do_catchsql_test(
+	"pragma-3.2",
+	[[
+		pragma sql_default_engine='memtx';
+		pragma sql_default_engine;
+	]], {
+	-- <pragma-3.2>
+	0, {'memtx'}
+	-- <pragma-3.2>
 })
 
 test:finish_test()
-- 
2.7.4