Fixed error while using PosgreSQL reserved keyword in cursor operations

contrib/babelfishpg_tsql/src/cursor.c

@@ -1449,6 +1449,9 @@ execute_sp_cursoropen_common(int *stmt_handle, int *cursor_handle, const char *s
 	Portal		portal;
 	MemoryContext oldcontext;
 	MemoryContext savedPortalCxt;
+	PLtsql_stmt_execsql *parse_result;
+	PLtsql_function *func;
+	char *stmt_copy;
 
 	/*
 	 * Connect to SPI manager. should be handled in the same way with
@@ -1468,6 +1471,42 @@ execute_sp_cursoropen_common(int *stmt_handle, int *cursor_handle, const char *s
 
 	if (prepare)
 	{
+		/*
+		 * This entire block is to parse the statement by antlr and use the resultant
+		 * statement to sent to Postgres cursor execution. This is necessary in some use case,
+		 * for example when we have PostgreSQL reversed keywords in query which is valid in TSQL.
+		 * Antlr parser will add the quotes at necessary places in query so that Postgres engine
+		 * can resolve this query correctly.
+		 */
+		if (stmt)
+		{
+			/* Copy the original statement, because we don't want to use the resultant query in every case. */
+			stmt_copy = pstrdup(stmt);
+			/* Send to antlr parser */
+			func = pltsql_compile_inline(stmt_copy, NULL);
+
+			/*
+			 * Check the node list of type PLtsql_stmt_type. Cursor only support single statement.
+			 * If there are more than 1 statement we will through the error. func->action-body
+			 * returned by pltsql_compile_inline contains two default nodes, PLTSQL_STMT_INIT being first
+			 * and PLTSQL_STMT_RETURN being last. So total number of nodes should be 3 for cursor. Actual
+			 * query statement will be at second position of type PLTSQL_STMT_EXECSQL.
+
+			 * This is defensive code, where we only reassign the stmt variable to parsed query,
+			 * if the cmd_type is PLTSQL_STMT_EXECSQL. There might be other types of cmd_type like
+			 * PLTSQL_STMT_EXECSQL (for procedures), for them we will keep the old behavior.
+			 */
+			if((( (PLtsql_stmt *) lsecond(func->action->body))->cmd_type == PLTSQL_STMT_EXECSQL)
+				&& list_length(func->action->body) == 3)
+			{
+				parse_result = (PLtsql_stmt_execsql *) lsecond(func->action->body);
+				stmt = pstrdup(parse_result->sqlstmt->query);
+			}
+
+			/*Free up function memory as this is not needed anymore */
+			pltsql_free_function_memory(func);
+		}
+
 		/* prepare plan and insert a cursor entry */
 		plan = SPI_prepare_cursor(stmt, nBindParams, boundParamsOidList, cursor_options);
 		if (plan == NULL)

test/JDBC/expected/TestCursorFetchNext.out

@@ -64,6 +64,44 @@ int#!#smallint#!#bigint#!#tinyint#!#bit
 #cursor#!#fetch#!#next
 #cursor#!#fetch#!#afterlast
 #cursor#!#fetch#!#next
+cursor#!#close
+~~SUCCESS~~
+cursor#!#open#!#SELECT a year, b month, c quarter FROM test_cursors_fetch_next#!#TYPE_SCROLL_INSENSITIVE#!#CONCUR_READ_ONLY#!#CLOSE_CURSORS_AT_COMMIT
+~~SUCCESS~~
+cursor#!#fetch#!#next
+~~START~~
+int#!#smallint#!#bigint
+0#!#0#!#0
+~~END~~
+
+cursor#!#fetch#!#first
+~~START~~
+int#!#smallint#!#bigint
+0#!#0#!#0
+~~END~~
+
+cursor#!#fetch#!#next
+~~START~~
+int#!#smallint#!#bigint
+<NULL>#!#<NULL>#!#<NULL>
+~~END~~
+
+cursor#!#fetch#!#last
+~~START~~
+int#!#smallint#!#bigint
+211234#!#9780#!#891372401
+~~END~~
+
+cursor#!#close
+~~SUCCESS~~
+cursor#!#open#!#DECLARE @var INT; select @var = 5; select @var + 1;#!#CONCUR_READ_ONLY#!#CLOSE_CURSORS_AT_COMMIT
+~~SUCCESS~~
+cursor#!#fetch#!#next
+~~START~~
+int
+6
+~~END~~
+
 cursor#!#close
 ~~SUCCESS~~
 DROP TABLE test_cursors_fetch_next

test/JDBC/expected/TestCursorPrepExecFetchNext.out

@@ -69,6 +69,38 @@ int#!#smallint#!#bigint#!#tinyint#!#bit
 #cursor#!#fetch#!#next
 #cursor#!#fetch#!#afterlast
 #cursor#!#fetch#!#next
+cursor#!#close
+~~SUCCESS~~
+cursor#!#open#!#prepst#!#SELECT a year, b month, c quarter from test_cursor_prep_exec_fetch_next#!#TYPE_SCROLL_INSENSITIVE#!#CONCUR_READ_ONLY#!#CLOSE_CURSORS_AT_COMMIT
+~~SUCCESS~~
+cursor#!#fetch#!#next
+~~START~~
+int#!#smallint#!#bigint
+0#!#0#!#0
+~~END~~
+
+cursor#!#fetch#!#first
+~~START~~
+int#!#smallint#!#bigint
+0#!#0#!#0
+~~END~~
+
+cursor#!#fetch#!#next
+~~START~~
+int#!#smallint#!#bigint
+<NULL>#!#<NULL>#!#<NULL>
+~~END~~
+
+cursor#!#close
+~~SUCCESS~~
+cursor#!#open#!#DECLARE @var INT; select @var = 5; select @var + 1;#!#CONCUR_READ_ONLY#!#CLOSE_CURSORS_AT_COMMIT
+~~SUCCESS~~
+cursor#!#fetch#!#next
+~~START~~
+int
+6
+~~END~~
+
 cursor#!#close
 ~~SUCCESS~~
 DROP TABLE test_cursor_prep_exec_fetch_next

test/JDBC/input/cursors/TestCursorFetchNext.txt

@@ -20,6 +20,15 @@ cursor#!#fetch#!#next
 #cursor#!#fetch#!#afterlast
 #cursor#!#fetch#!#next
 cursor#!#close
+cursor#!#open#!#SELECT a year, b month, c quarter FROM test_cursors_fetch_next#!#TYPE_SCROLL_INSENSITIVE#!#CONCUR_READ_ONLY#!#CLOSE_CURSORS_AT_COMMIT
+cursor#!#fetch#!#next
+cursor#!#fetch#!#first
+cursor#!#fetch#!#next
+cursor#!#fetch#!#last
+cursor#!#close
+cursor#!#open#!#DECLARE @var INT; select @var = 5; select @var + 1;#!#CONCUR_READ_ONLY#!#CLOSE_CURSORS_AT_COMMIT
+cursor#!#fetch#!#next
+cursor#!#close
 DROP TABLE test_cursors_fetch_next
 
 CREATE TABLE test_cursors_fetch_next(a CHAR(30), b VARCHAR(30), c NCHAR(30), d NVARCHAR(30));

test/JDBC/input/cursors/TestCursorPrepExecFetchNext.txt

@@ -23,6 +23,14 @@ cursor#!#fetch#!#next
 #cursor#!#fetch#!#afterlast
 #cursor#!#fetch#!#next
 cursor#!#close
+cursor#!#open#!#prepst#!#SELECT a year, b month, c quarter from test_cursor_prep_exec_fetch_next#!#TYPE_SCROLL_INSENSITIVE#!#CONCUR_READ_ONLY#!#CLOSE_CURSORS_AT_COMMIT
+cursor#!#fetch#!#next
+cursor#!#fetch#!#first
+cursor#!#fetch#!#next
+cursor#!#close
+cursor#!#open#!#DECLARE @var INT; select @var = 5; select @var + 1;#!#CONCUR_READ_ONLY#!#CLOSE_CURSORS_AT_COMMIT
+cursor#!#fetch#!#next
+cursor#!#close
 DROP TABLE test_cursor_prep_exec_fetch_next
 
 CREATE TABLE test_cursor_prep_exec_fetch_next(a CHAR(30), b VARCHAR(30), c NCHAR(30), d NVARCHAR(30));