Reduce SAVEPOINT calls especially in use declare/fetch mode by omitting SAVEPOINT calls after read-only statements(queries).

Note that DECLARE command is not thought to be read-only because the cursor disappears when rolled back to a savepoint established before the DECLARE command.

10 files changed, 137 insertions, 81 deletions

diff --git a/connection.c b/connection.c
index c72f94d..e2ae5ed 100644
--- a/connection.c
+++ b/connection.c
@@ -1022,7 +1022,7 @@ LIBPQ_CC_connect(ConnectionClass *self, char *salt_para)
 
 	if (ret = LIBPQ_connect(self), ret <= 0)
 		return ret;
-	res = CC_send_query(self, "SET DateStyle = 'ISO';SET extra_float_digits = 2;" ISOLATION_SHOW_QUERY, NULL, 0, NULL);
+	res = CC_send_query(self, "SET DateStyle = 'ISO';SET extra_float_digits = 2;" ISOLATION_SHOW_QUERY, NULL, READ_ONLY_QUERY, NULL);
 	if (QR_command_maybe_successful(res))
 	{
 		handle_show_results(res);
@@ -1242,7 +1242,7 @@ int	CC_get_max_idlen(ConnectionClass *self)
 	{
 		QResultClass	*res;
 
-		res = CC_send_query(self, "show max_identifier_length", NULL, ROLLBACK_ON_ERROR | IGNORE_ABORT_ON_CONN, NULL);
+		res = CC_send_query(self, "show max_identifier_length", NULL, READ_ONLY_QUERY, NULL);
 		if (QR_command_maybe_successful(res))
 			len = self->max_identifier_length = QR_get_value_backend_int(res, 0, 0, FALSE);
 		QR_Destructor(res);
@@ -1302,7 +1302,7 @@ SQLUINTEGER	CC_get_isolation(ConnectionClass *self)
 	SQLUINTEGER	isolation = 0;
 	QResultClass	*res;
 
-	res = CC_send_query(self, ISOLATION_SHOW_QUERY, NULL, ROLLBACK_ON_ERROR | IGNORE_ABORT_ON_CONN, NULL);
+	res = CC_send_query(self, ISOLATION_SHOW_QUERY, NULL, READ_ONLY_QUERY, NULL);
 	if (QR_command_maybe_successful(res))
 	{
 		handle_show_results(res);
@@ -1430,7 +1430,7 @@ static void CC_clear_cursors(ConnectionClass *self, BOOL on_abort)
 				{
 					SPRINTF_FIXED(cmd, "MOVE 0 in \"%s\"", QR_get_cursor(res));
 					CONNLOCK_RELEASE(self);
-					wres = CC_send_query(self, cmd, NULL, ROLLBACK_ON_ERROR | IGNORE_ABORT_ON_CONN, NULL);
+					wres = CC_send_query(self, cmd, NULL, ROLLBACK_ON_ERROR | IGNORE_ABORT_ON_CONN | READ_ONLY_QUERY, NULL);
 					QR_set_no_survival_check(res);
 					if (QR_command_maybe_successful(wres))
 						QR_set_permanent(res);
@@ -1476,7 +1476,7 @@ void	CC_on_commit(ConnectionClass *conn)
 		CC_set_no_trans(conn);
 		CC_set_no_manual_trans(conn);
 	}
-	conn->internal_svp = conn->is_in_internal_op = 0;
+	CC_svp_init(conn);
 	CC_start_stmt(conn);
 	CC_clear_cursors(conn, FALSE);
 	CONNLOCK_RELEASE(conn);
@@ -1508,7 +1508,7 @@ mylog("CC_on_abort in opt=%x\n", opt);
 			set_no_trans = TRUE;
 		}
 	}
-	conn->internal_svp = conn->is_in_internal_op = 0;
+	CC_svp_init(conn);
 	CC_start_stmt(conn);
 	CC_clear_cursors(conn, TRUE);
 	if (0 != (opt & CONN_DEAD))
@@ -1542,11 +1542,13 @@ void	CC_on_abort_partial(ConnectionClass *conn)
 {
 mylog("CC_on_abort_partial in\n");
 	CONNLOCK_ACQUIRE(conn);
-	if (!conn->is_in_internal_op)	/* manually rolling back to */
+	if (!conn->internal_op)	/* manually rolling back to */
 	{
 		conn->internal_svp = 0; /* possibly an internal savepoint is invalid */
 		mylog(" %s:reset an internal savepoint\n", __FUNCTION__);
+		conn->opt_previous = 0; /* unknown */
 	}
+	CC_init_opt_in_progress(conn);
 	ProcessRollback(conn, TRUE, TRUE);
 	CC_discard_marked_objects(conn);
 	CONNLOCK_RELEASE(conn);
@@ -1623,7 +1625,7 @@ CC_send_query_append(ConnectionClass *self, const char *query, QueryInfo *qi, UD
 	BOOL	ignore_abort_on_conn = ((flag & IGNORE_ABORT_ON_CONN) != 0),
 		create_keyset = ((flag & CREATE_KEYSET) != 0),
 		issue_begin = ((flag & GO_INTO_TRANSACTION) != 0 && !CC_is_in_trans(self)),
-		rollback_on_error, query_rollback, end_with_commit;
+		rollback_on_error, query_rollback, end_with_commit, read_only;
 
 	char		*ptr;
 	BOOL		ReadyToReturn = FALSE,
@@ -1694,6 +1696,7 @@ CC_send_query_append(ConnectionClass *self, const char *query, QueryInfo *qi, UD
 
 	rollback_on_error = (flag & ROLLBACK_ON_ERROR) != 0;
 	end_with_commit = (flag & END_WITH_COMMIT) != 0;
+	read_only = (flag & READ_ONLY_QUERY) != 0;
 #define	return DONT_CALL_RETURN_FROM_HERE???
 	consider_rollback = (issue_begin || (CC_is_in_trans(self) && !CC_is_in_error_trans(self)) || strnicmp(query, "begin", 5) == 0);
 	if (rollback_on_error)
@@ -1704,9 +1707,13 @@ CC_send_query_append(ConnectionClass *self, const char *query, QueryInfo *qi, UD
 		if (stmt)
 		{
 			StatementClass	*astmt = SC_get_ancestor(stmt);
+			unsigned int svpopt = 0;
+
+			if (read_only)
+				svpopt |= SVPOPT_RDONLY;
 			if (!CC_started_rbpoint(self))
 			{
-				if (SQL_ERROR == SetStatementSvp(astmt))
+				if (SQL_ERROR == SetStatementSvp(astmt, svpopt))
 				{
 					SC_set_error(stmt, STMT_INTERNAL_ERROR, "internal savepoint error", func);
 					goto cleanup;
@@ -1722,9 +1729,7 @@ CC_send_query_append(ConnectionClass *self, const char *query, QueryInfo *qi, UD
 		+ strlen(svpcmd) + 1 + strlen(per_query_svp) + 1
 		+ query_len
 		+ (appendq ? (1 + strlen(appendq)) : 0)
-#ifdef	_RELEASE_INTERNAL_SAVEPOINT
 		+ 1 + strlen(rlscmd) + strlen(per_query_svp)
-#endif /* _RELEASE_INTERNAL_SAVEPOINT */
 		+ 1;
 	query_buf = malloc(query_buf_len);
 	if (!query_buf)
@@ -1748,12 +1753,10 @@ CC_send_query_append(ConnectionClass *self, const char *query, QueryInfo *qi, UD
 	{
 		snprintfcat(query_buf, query_buf_len, ";%s", appendq);
 	}
-#ifdef	_RELEASE_INTERNAL_SAVEPOINT
 	if (query_rollback)
 	{
 		snprintfcat(query_buf, query_buf_len, ";%s %s", rlscmd, per_query_svp);
 	}
-#endif /* _RELEASE_INTERNAL_SAVEPOINT */
 
 	/* Set up notice receiver */
 	nrarg.conn = self;
@@ -1800,22 +1803,7 @@ CC_send_query_append(ConnectionClass *self, const char *query, QueryInfo *qi, UD
 				/* read in the return message from the backend */
 				cmdbuffer = PQcmdStatus(pgres);
 				mylog("send_query: ok - 'C' - %s\n", cmdbuffer);
-#ifdef	_RELEASE_INTERNAL_SAVEPOINT
-				/*
-				 * There are 2 risks to RELEASE an internal savepoint.
-				 * One is to RELEASE the savepoint invalitated
-				 * due to manually issued ROLLBACK or RELEASE.
-				 * Another is to invalitate manual SAVEPOINTs unexpectedly
-				 * by RELEASing the internal savepoint.
-				 */
-				if (!self->is_in_internal_op && self->internal_svp)
-				{
-					if (0 == stricmp(cmdbuffer, rlscmd) ||
-					    0 == stricmp(cmdbuffer, rbkcmd) ||
-					    0 == stricmp(cmdbuffer, svpcmd))
-						self->internal_svp = 0;
-				}
-#endif /* _RELEASE_INTERNAL_SAVEPOINT */
+
 
 				if (query_completed)	/* allow for "show" style notices */
 				{
@@ -1843,6 +1831,13 @@ CC_send_query_append(ConnectionClass *self, const char *query, QueryInfo *qi, UD
 						break; /* discard the result */
 					}
 				}
+				/*
+				 * There are 2 risks to RELEASE an internal savepoint.
+				 * One is to RELEASE the savepoint invalitated
+				 * due to manually issued ROLLBACK or RELEASE.
+				 * Another is to invalitate manual SAVEPOINTs unexpectedly
+				 * by RELEASing the internal savepoint.
+				 */
 				else if (strnicmp(cmdbuffer, svpcmd, strlen(svpcmd)) == 0)
 				{
 					if (discard_next_savepoint)
@@ -1851,11 +1846,28 @@ inolog("Discarded the first SAVEPOINT\n");
 						discard_next_savepoint = FALSE;
 						break; /* discard the result */
 					}
+					if (SAVEPOINT_IN_PROGRESS == self->internal_op)
+					{
+						CC_start_rbpoint(self);
+						self->internal_op = 0;
+						break; /* discard the result */
+					}
+					/* Don't release the internal savepoint */
+					self->internal_svp = 0;
 				}
 				else if (strnicmp(cmdbuffer, rbkcmd, strlen(rbkcmd)) == 0)
 				{
 					CC_mark_cursors_doubtful(self);
 					CC_set_in_error_trans(self); /* mark the transaction error in case of manual rollback */
+					if (!self->internal_op)
+						self->internal_svp = 0;
+				}
+				else if (strnicmp(cmdbuffer, rlscmd, strlen(rlscmd)) == 0)
+				{
+					if (SAVEPOINT_IN_PROGRESS == self->internal_op)
+						break; /* discard the result */
+					else /* internal savepoint may become invalid */
+						self->internal_svp = 0;
 				}
 				/*
 				 *	DROP TABLE or ALTER TABLE may change
@@ -2027,20 +2039,13 @@ cleanup:
 			if (CC_is_in_error_trans(self))
 			{
 				char tmpsqlbuf[100];
-#ifdef	_RELEASE_INTERNAL_SAVEPOINT
+
 				SPRINTF_FIXED(tmpsqlbuf,
 						"%s TO %s"
 						";%s %s"
 						, rbkcmd, per_query_svp
 						, rlscmd, per_query_svp);
-#else
-				SPRINTF_FIXED(tmpsqlbuf,
-						"%s TO %s"
-						, rbkcmd, per_query_svp);
-#endif /* _RELEASE_INTERNAL_SAVEPOINT */
-				self->is_in_internal_op = 1;
 				pgres = PQexec(self->pqconn, tmpsqlbuf);
-				self->is_in_internal_op = 0;
 				/*
 				 * Though it's not appropriate to
 				 * call PQExec for a multiple command,
@@ -2366,7 +2371,7 @@ CC_lookup_lo(ConnectionClass *self)
 	mylog("%s: entering...\n", func);
 
 	res = CC_send_query(self, "select oid, typbasetype from pg_type where typname = '"  PG_TYPE_LO_NAME "'",
-		NULL, IGNORE_ABORT_ON_CONN | ROLLBACK_ON_ERROR, NULL);
+		NULL, READ_ONLY_QUERY, NULL);
 	if (QR_command_maybe_successful(res) && QR_get_num_cached_tuples(res) > 0)
 	{
 		OID	basetype;
@@ -2430,7 +2435,7 @@ CC_get_current_schema(ConnectionClass *conn)
 	{
 		QResultClass	*res;
 
-		if (res = CC_send_query(conn, "select current_schema()", NULL, IGNORE_ABORT_ON_CONN | ROLLBACK_ON_ERROR, NULL), QR_command_maybe_successful(res))
+		if (res = CC_send_query(conn, "select current_schema()", NULL, READ_ONLY_QUERY, NULL), QR_command_maybe_successful(res))
 		{
 			if (QR_get_num_total_tuples(res) == 1)
 			{
@@ -2478,7 +2483,7 @@ int	CC_discard_marked_objects(ConnectionClass *conn)
 			SPRINTF_FIXED(cmd, "DEALLOCATE \"%s\"", pname + 1);
 		else
 			SPRINTF_FIXED(cmd, "CLOSE \"%s\"", pname + 1);
-		res = CC_send_query(conn, cmd, NULL, ROLLBACK_ON_ERROR | IGNORE_ABORT_ON_CONN, NULL);
+		res = CC_send_query(conn, cmd, NULL, ROLLBACK_ON_ERROR | IGNORE_ABORT_ON_CONN | READ_ONLY_QUERY, NULL);
 		QR_Destructor(res);
 		free(conn->discardp[i]);
 		conn->num_discardp--;
@@ -3338,9 +3343,9 @@ CC_set_transact(ConnectionClass *self, UInt4 isolation)
 	if (self->default_isolation == 0)
 		bShow = TRUE;
 	if (bShow)
-		res = CC_send_query_append(self, ISOLATION_SHOW_QUERY, NULL, 0, NULL, query);
+		res = CC_send_query_append(self, ISOLATION_SHOW_QUERY, NULL, READ_ONLY_QUERY, NULL, query);
 	else
-		res = CC_send_query(self, query, NULL, 0, NULL);
+		res = CC_send_query(self, query, NULL, READ_ONLY_QUERY, NULL);
 	if (!QR_command_maybe_successful(res))
 	{
 		CC_set_error(self, CONN_EXEC_ERROR, "ISOLATION change request to the server error", __FUNCTION__);
diff --git a/connection.h b/connection.h
index 5bc0f71..37f04e2 100644
--- a/connection.h
+++ b/connection.h
@@ -311,9 +311,11 @@ struct ConnectionClass_
 						 * unknown */
 	/* for per statement rollback */
 	char		internal_svp;		/* is set? */
-	char		is_in_internal_op;	/* an operation as to internal savepoint in progress */
+	char		internal_op;		/* operation being executed as to internal savepoint */
 	unsigned char	lock_CC_for_rb;
 	unsigned char	rbonerr;
+	unsigned char	opt_in_progress;
+	unsigned char	opt_previous;
 
 	char		*original_client_encoding;
 	char		*locale_encoding;
@@ -388,7 +390,7 @@ enum {
 #define CC_is_rb_stmt(a)        (((a)->rbonerr & (1L << 2)) != 0)
 #define CC_set_accessed_db(a)   ((a)->rbonerr |= (1L << 3))
 #define CC_accessed_db(a)       (((a)->rbonerr & (1L << 3)) != 0)
-#define CC_start_rbpoint(a)     ((a)->rbonerr |= (1L << 4))
+#define CC_start_rbpoint(a)     ((a)->rbonerr |= (1L << 4), (a)->internal_svp = 1)
 #define CC_started_rbpoint(a)   (((a)->rbonerr & (1L << 4)) != 0)
 
 /*	prototypes */
@@ -456,13 +458,32 @@ enum {
 	,GO_INTO_TRANSACTION	= (1L << 2) /* issue BEGIN in advance */
 	,ROLLBACK_ON_ERROR	= (1L << 3) /* rollback the query when an error occurs */
 	,END_WITH_COMMIT	= (1L << 4) /* the query ends with COMMIT command */
+	,READ_ONLY_QUERY	= (1L << 5) /* the query is read-only */
 };
 /* CC_on_abort options */
 #define	NO_TRANS		1L
 #define	CONN_DEAD		(1L << 1) /* connection is no longer valid */
 
+/*
+ *	internal savepoint related
+ */
+
 #define	_RELEASE_INTERNAL_SAVEPOINT
 
+/*      Operations about internal savepoint */
+enum {
+        SAVEPOINT_IN_PROGRESS = 1
+        ,ROLLBACK_IN_PROGRESS = 2
+};
+/*      StatementSvp entry option */
+enum {
+        SVPOPT_RDONLY = 1L
+};
+#define	INIT_SVPOPT	(SVPOPT_RDONLY)
+#define CC_svp_init(a) ((a)->internal_svp = (a)->internal_op = 0, (a)->opt_in_progress = (a)->opt_previous = INIT_SVPOPT)
+#define CC_init_opt_in_progress(a) ((a)->opt_in_progress = INIT_SVPOPT)
+#define CC_init_opt_previous(a) ((a)->opt_previous = INIT_SVPOPT)
+
 #ifdef	__cplusplus
 }
 #endif
diff --git a/execute.c b/execute.c
index 65d3bb9..df0abc7 100644
--- a/execute.c
+++ b/execute.c
@@ -168,6 +168,8 @@ inolog("a2\n");
 
 	if (0 != (flag & PODBC_WITH_HOLD))
 		SC_set_with_hold(stmt);
+	if (0 != (flag & PODBC_RDONLY))
+		SC_set_readonly(stmt);
 
 	/*
 	 * If an SQLPrepare was performed prior to this, but was left in the
@@ -588,7 +590,7 @@ inolog("%s:%p->external=%d\n", func, stmt, stmt->external);
  *	invokes a transaction.
  */
 RETCODE
-SetStatementSvp(StatementClass *stmt)
+SetStatementSvp(StatementClass *stmt, unsigned int option)
 {
 	CSTR	func = "SetStatementSvp";
 	char	esavepoint[32], cmd[64];
@@ -609,13 +611,16 @@ SetStatementSvp(StatementClass *stmt)
 		ENTER_CONN_CS(conn);
 		conn->lock_CC_for_rb++;
 	}
+inolog(" !!!! %s:%p->accessed=%d opt=%u in_progress=%u prev=%u\n", __FUNCTION__, conn, CC_accessed_db(conn), option, conn->opt_in_progress, conn->opt_previous);
+	conn->opt_in_progress &= option;
 	switch (stmt->statement_type)
 	{
 		case STMT_TYPE_SPECIAL:
 		case STMT_TYPE_TRANSACTION:
 			return ret;
 	}
-	if (!CC_started_rbpoint(conn))
+	/* If rbpoint is not yet started and the previous statement was not read-only */
+	if (!CC_started_rbpoint(conn) && 0 == (conn->opt_previous & SVPOPT_RDONLY))
 	{
 		BOOL	need_savep = FALSE;
 
@@ -638,13 +643,13 @@ SetStatementSvp(StatementClass *stmt)
 			conn->internal_svp = 1;
 			SPRINTFCAT_FIXED(cmd, "SAVEPOINT %s", GetSvpName(conn, esavepoint, sizeof(esavepoint)));
 			conn->internal_svp = internal_svp;
-			conn->is_in_internal_op = 1;
+			conn->internal_op = SAVEPOINT_IN_PROGRESS;
 			res = CC_send_query(conn, cmd, NULL, 0, NULL);
-			conn->is_in_internal_op = 0;
+			conn->internal_op = 0;
 			if (QR_command_maybe_successful(res))
 			{
-				conn->internal_svp = 1;
-				CC_start_rbpoint(conn);
+				// conn->internal_svp = 1;
+				// CC_start_rbpoint(conn);
 				ret = SQL_SUCCESS;
 			}
 			else
@@ -654,8 +659,8 @@ SetStatementSvp(StatementClass *stmt)
 			}
 			QR_Destructor(res);
 		}
-		CC_set_accessed_db(conn);
 	}
+	CC_set_accessed_db(conn);
 inolog("%s:%p->accessed=%d\n", func, conn, CC_accessed_db(conn));
 	return ret;
 }
@@ -671,6 +676,8 @@ DiscardStatementSvp(StatementClass *stmt, RETCODE ret, BOOL errorOnly)
 
 inolog("%s:%p->accessed=%d is_in=%d is_rb=%d is_tc=%d\n", func, conn, CC_accessed_db(conn),
 CC_is_in_trans(conn), SC_is_rb_stmt(stmt), SC_is_tc_stmt(stmt));
+	if (conn->lock_CC_for_rb > 0)
+		mylog("%s:in_progress=%u previous=%d\n", func, conn->opt_in_progress, conn->opt_previous);
 	switch (ret)
 	{
 		case SQL_NEED_DATA:
@@ -694,9 +701,9 @@ CC_is_in_trans(conn), SC_is_rb_stmt(stmt), SC_is_tc_stmt(stmt));
 			char esavepoint[32];
 
 			SPRINTF_FIXED(cmd, "ROLLBACK to %s", GetSvpName(conn, esavepoint, sizeof(esavepoint)));
-			conn->is_in_internal_op = 1;
+			conn->internal_op = ROLLBACK_IN_PROGRESS;
 			res = CC_send_query(conn, cmd, NULL, IGNORE_ABORT_ON_CONN, NULL);
-			conn->is_in_internal_op = 0;
+			conn->internal_op = 0;
 			cmd_success = QR_command_maybe_successful(res);
 			QR_Destructor(res);
 			if (!cmd_success)
@@ -722,10 +729,17 @@ cleanup:
 #endif
 	if (start_stmt || SQL_ERROR == ret)
 	{
+		stmt->execinfo = 0;
+		if (SQL_ERROR != ret && CC_accessed_db(conn))
+		{
+			conn->opt_previous = conn->opt_in_progress;
+			CC_init_opt_in_progress(conn);
+		}
 		while (conn->lock_CC_for_rb > 0)
 		{
 			LEAVE_CONN_CS(conn);
 			conn->lock_CC_for_rb--;
+			inolog(" %s:release conn_lock\n", __FUNCTION__);
 		}
 		CC_start_stmt(conn);
 	}
diff --git a/info.c b/info.c
index b1b5f16..d1ac550 100644
--- a/info.c
+++ b/info.c
@@ -1894,7 +1894,7 @@ retry_public_schema:
 	else
 		STRCAT_FIXED(tables_query, " and n.oid = relnamespace order by nspname, relname");
 
-	result = PGAPI_ExecDirect(htbl_stmt, (SQLCHAR *) tables_query, SQL_NTS, 0);
+	result = PGAPI_ExecDirect(htbl_stmt, (SQLCHAR *) tables_query, SQL_NTS, PODBC_RDONLY);
 	if (!SQL_SUCCEEDED(result))
 	{
 		SC_full_error_copy(stmt, htbl_stmt, FALSE);
@@ -2288,7 +2288,7 @@ retry_public_schema:
 
 	mylog("%s: hcol_stmt = %p, col_stmt = %p\n", func, hcol_stmt, col_stmt);
 
-	result = PGAPI_ExecDirect(hcol_stmt, (SQLCHAR *) columns_query, SQL_NTS, 0);
+	result = PGAPI_ExecDirect(hcol_stmt, (SQLCHAR *) columns_query, SQL_NTS, PODBC_RDONLY);
 	if (!SQL_SUCCEEDED(result))
 	{
 		SC_full_error_copy(stmt, col_stmt, FALSE);
@@ -2776,7 +2776,7 @@ retry_public_schema:
 
 	mylog("%s: hcol_stmt = %p, col_stmt = %p\n", func, hcol_stmt, col_stmt);
 
-	result = PGAPI_ExecDirect(hcol_stmt, (SQLCHAR *) columns_query, SQL_NTS, 0);
+	result = PGAPI_ExecDirect(hcol_stmt, (SQLCHAR *) columns_query, SQL_NTS, PODBC_RDONLY);
 	if (!SQL_SUCCEEDED(result))
 	{
 		SC_full_error_copy(stmt, col_stmt, FALSE);
@@ -3160,7 +3160,7 @@ PGAPI_Statistics(HSTMT hstmt,
 	STRCAT_FIXED(index_query, " i.indisprimary desc,");
 	STRCAT_FIXED(index_query, " i.indisunique, n.nspname, c.relname");
 
-	result = PGAPI_ExecDirect(hindx_stmt, (SQLCHAR *) index_query, SQL_NTS, 0);
+	result = PGAPI_ExecDirect(hindx_stmt, (SQLCHAR *) index_query, SQL_NTS, PODBC_RDONLY);
 	if (!SQL_SUCCEEDED(result))
 	{
 		/*
@@ -3762,7 +3762,7 @@ retry_public_schema:
 		}
 		mylog("%s: tables_query='%s'\n", func, tables_query);
 
-		result = PGAPI_ExecDirect(htbl_stmt, (SQLCHAR *) tables_query, SQL_NTS, 0);
+		result = PGAPI_ExecDirect(htbl_stmt, (SQLCHAR *) tables_query, SQL_NTS, PODBC_RDONLY);
 		if (!SQL_SUCCEEDED(result))
 		{
 			SC_full_error_copy(stmt, tbl_stmt, FALSE);
@@ -4141,7 +4141,7 @@ PGAPI_ForeignKeys_old(HSTMT hstmt,
 			eq_string, escFkTableName, eq_string, escSchemaName);
 		free(escSchemaName);
 
-		result = PGAPI_ExecDirect(htbl_stmt, (SQLCHAR *) tables_query, SQL_NTS, 0);
+		result = PGAPI_ExecDirect(htbl_stmt, (SQLCHAR *) tables_query, SQL_NTS, PODBC_RDONLY);
 
 		if (!SQL_SUCCEEDED(result))
 		{
@@ -4469,7 +4469,7 @@ PGAPI_ForeignKeys_old(HSTMT hstmt,
 			eq_string, escPkTableName, eq_string, escSchemaName);
 		free(escSchemaName);
 
-		result = PGAPI_ExecDirect(htbl_stmt, (SQLCHAR *) tables_query, SQL_NTS, 0);
+		result = PGAPI_ExecDirect(htbl_stmt, (SQLCHAR *) tables_query, SQL_NTS, PODBC_RDONLY);
 		if (!SQL_SUCCEEDED(result))
 		{
 			SC_error_copy(stmt, tbl_stmt, TRUE);
diff --git a/parse.c b/parse.c
index 3380c9f..5866c7a 100644
--- a/parse.c
+++ b/parse.c
@@ -394,7 +394,7 @@ static BOOL CheckHasOids(StatementClass * stmt)
 	SPRINTF_FIXED(query,
 			 "select relhasoids, c.oid, relhassubclass from pg_class c, pg_namespace n where relname = '%s' and nspname = '%s' and c.relnamespace = n.oid",
 			 SAFE_NAME(ti->table_name), SAFE_NAME(ti->schema_name));
-	res = CC_send_query(conn, query, NULL, ROLLBACK_ON_ERROR | IGNORE_ABORT_ON_CONN, NULL);
+	res = CC_send_query(conn, query, NULL, READ_ONLY_QUERY, NULL);
 	if (QR_command_maybe_successful(res))
 	{
 		stmt->num_key_fields = PG_NUM_NORMAL_KEYS;
@@ -433,7 +433,7 @@ static BOOL CheckHasOids(StatementClass * stmt)
 		if (!hasoids && !hassubclass)
 		{
 			SPRINTF_FIXED(query, "select a.attname, a.atttypid from pg_index i, pg_attribute a where indrelid=%u and indnatts=1 and indisunique and indexprs is null and indpred is null and i.indrelid = a.attrelid and a.attnum=i.indkey[0] and attnotnull and atttypid in (%d, %d)", ti->table_oid, PG_TYPE_INT4, PG_TYPE_OID);
-			res = CC_send_query(conn, query, NULL, ROLLBACK_ON_ERROR | IGNORE_ABORT_ON_CONN, NULL);
+			res = CC_send_query(conn, query, NULL, READ_ONLY_QUERY, NULL);
 			if (QR_command_maybe_successful(res) && QR_get_num_total_tuples(res) > 0)
 			{
 				foundKey = TRUE;
@@ -772,7 +772,7 @@ COL_INFO **coli)
 					 "select nspname from pg_namespace n, pg_class c"
 					 " where c.relnamespace=n.oid and c.oid='\"%s\"'::regclass",
 					 SAFE_NAME(table_name));
-			res = CC_send_query(conn, token, NULL, ROLLBACK_ON_ERROR | IGNORE_ABORT_ON_CONN, NULL);
+			res = CC_send_query(conn, token, NULL, READ_ONLY_QUERY, NULL);
 			if (QR_command_maybe_successful(res))
 			{
 				if (QR_get_num_total_tuples(res) == 1)
diff --git a/pgapifunc.h b/pgapifunc.h
index 9902a6a..8b311f7 100644
--- a/pgapifunc.h
+++ b/pgapifunc.h
@@ -24,6 +24,7 @@ extern "C" {
 #define	PODBC_INHERIT_CONNECT_OPTIONS	(1L << 1)
 /*	Internal flags for PGAPI_Exec... functions */
 #define	PODBC_WITH_HOLD			1L
+#define	PODBC_RDONLY			(1L << 1)
 /*	Flags for the error handling */
 #define	PODBC_ALLOW_PARTIAL_EXTRACT	1L
 #define	PODBC_ERROR_CLEAR		(1L << 1)
diff --git a/qresult.c b/qresult.c
index ff48814..96a8410 100644
--- a/qresult.c
+++ b/qresult.c
@@ -739,8 +739,9 @@ QR_close(QResultClass *self)
 			UDWORD		flag = 0;
 			char		buf[64];
 
+			flag = READ_ONLY_QUERY;
 			if (QR_needs_survival_check(self))
-				flag = ROLLBACK_ON_ERROR | IGNORE_ABORT_ON_CONN;
+				flag |= (ROLLBACK_ON_ERROR | IGNORE_ABORT_ON_CONN);
 
 			SPRINTF_FIXED(buf, "close \"%s\"", QR_get_cursor(self));
 			/* End the transaction if there are no cursors left on this conn */
@@ -907,7 +908,7 @@ SQLLEN	QR_move_cursor_to_last(QResultClass *self, StatementClass *stmt)
 		return 0;
 	SPRINTF_FIXED(movecmd,
 		 "move all in \"%s\"", QR_get_cursor(self));
-	res = CC_send_query(conn, movecmd, NULL, 0, stmt);
+	res = CC_send_query(conn, movecmd, NULL, READ_ONLY_QUERY, stmt);
 	if (!QR_command_maybe_successful(res))
 	{
 		QR_Destructor(res);
@@ -1006,7 +1007,7 @@ inolog("cache=%d rowset=%d movement=" FORMAT_ULEN "\n", self->cache_size, req_si
 					 QR_get_cursor(self));
 			movement = INT_MAX;
 		}
-		mres = CC_send_query(conn, movecmd, NULL, 0, stmt);
+		mres = CC_send_query(conn, movecmd, NULL, READ_ONLY_QUERY, stmt);
 		if (!QR_command_maybe_successful(mres))
 		{
 			QR_Destructor(mres);
@@ -1158,7 +1159,7 @@ inolog("clear obsolete %d tuples\n", num_backend_rows);
 	qi.fetch_size = fetch_size;
 	qi.result_in = self;
 	qi.cursor = NULL;
-	res = CC_send_query(conn, fetch, &qi, 0, stmt);
+	res = CC_send_query(conn, fetch, &qi, READ_ONLY_QUERY, stmt);
 	if (!QR_command_maybe_successful(res))
 	{
 		if (!QR_get_message(self))
diff --git a/results.c b/results.c
index a120c32..74dd828 100644
--- a/results.c
+++ b/results.c
@@ -2177,7 +2177,7 @@ ti_quote(StatementClass *stmt, OID tableoid)
 		char	*ret = "";
 
 		SPRINTF_FIXED(query, "select relname, nspname from pg_class c, pg_namespace n where c.oid=%u and c.relnamespace=n.oid", tableoid);
-		res = CC_send_query(SC_get_conn(stmt), query, NULL, 0, stmt);
+		res = CC_send_query(SC_get_conn(stmt), query, NULL, READ_ONLY_QUERY, stmt);
 		if (QR_command_maybe_successful(res) &&
 		    QR_get_num_cached_tuples(res) == 1)
 		{
@@ -2210,7 +2210,7 @@ static BOOL	tupleExists(StatementClass *stmt, const KeySet *keyset)
 		SPRINTFCAT_FIXED(selstr, " and ");
 		SPRINTFCAT_FIXED(selstr, bestqual, keyset->oid);
 	}
-	res = CC_send_query(SC_get_conn(stmt), selstr, NULL, 0, NULL);
+	res = CC_send_query(SC_get_conn(stmt), selstr, NULL, READ_ONLY_QUERY, NULL);
 	if (QR_command_maybe_successful(res) && 1 == res->num_cached_rows)
 		ret = TRUE;
 	QR_Destructor(res);
@@ -3094,7 +3094,7 @@ inolog("%s bestitem=%s bestqual=%s\n", func, SAFE_NAME(ti->bestitem), SAFE_NAME(
 	}
 
 	mylog("selstr=%s\n", selstr);
-	qres = CC_send_query(SC_get_conn(stmt), selstr, NULL, 0, stmt);
+	qres = CC_send_query(SC_get_conn(stmt), selstr, NULL, READ_ONLY_QUERY, stmt);
 cleanup:
 	free(selstr);
 	return qres;
@@ -3311,7 +3311,7 @@ static SQLLEN LoadFromKeyset(StatementClass *stmt, QResultClass * res, int rows_
 			QResultClass	*qres;
 
 			strlcat(qval, ")", allen);
-			qres = CC_send_query(conn, qval, NULL, CREATE_KEYSET, stmt);
+			qres = CC_send_query(conn, qval, NULL, CREATE_KEYSET | READ_ONLY_QUERY, stmt);
 			if (QR_command_maybe_successful(qres))
 			{
 				SQLLEN		j, k, l;
@@ -3404,7 +3404,7 @@ static SQLLEN LoadFromKeyset(StatementClass *stmt, QResultClass * res, int rows_
 							snprintfcat(qval, allen, ",$%d", j + 1);
 					}
 					strlcat(qval, ")", allen);
-					qres = CC_send_query(conn, qval, NULL, 0, stmt);
+					qres = CC_send_query(conn, qval, NULL, READ_ONLY_QUERY, stmt);
 					if (QR_command_maybe_successful(qres))
 					{
 						res->reload_count = keys_per_fetch;
@@ -3486,7 +3486,7 @@ mylog(" %s in rows_per_fetch=%d limitrow=%d\n", __FUNCTION__, rows_per_fetch, li
 			QResultClass	*qres;
 
 			strlcat(qval, ")", allen);
-			qres = CC_send_query(conn, qval, NULL, CREATE_KEYSET, stmt);
+			qres = CC_send_query(conn, qval, NULL, CREATE_KEYSET | READ_ONLY_QUERY, stmt);
 			if (QR_command_maybe_successful(qres))
 			{
 				SQLLEN		k, l;
diff --git a/statement.c b/statement.c
index da326ff..9d2f7f5 100644
--- a/statement.c
+++ b/statement.c
@@ -445,6 +445,7 @@ SC_Constructor(ConnectionClass *conn)
 				rv, SQL_ATTR_IMP_PARAM_DESC);
 
 		rv->miscinfo = 0;
+		rv->execinfo = 0;
 		rv->rb_or_tc = 0;
 		SC_reset_updatable(rv);
 		rv->diag_row_count = 0;
@@ -853,6 +854,7 @@ inolog("SC_clear_parse_status\n");
 	if (SC_get_Result(self))
 		SC_set_Result(self, NULL);
 	self->miscinfo = 0;
+	self->execinfo = 0;
 	/* self->rbonerr = 0; Never clear the bits here */
 
 	/*
@@ -1085,6 +1087,7 @@ SC_describe(StatementClass *self)
 mylog("              preprocess: status = READY\n");
 
 		self->miscinfo = 0;
+		self->execinfo = 0;
 
 		decideHowToPrepare(self, FALSE);
 		switch (SC_get_prepare_method(self))
@@ -1932,6 +1935,7 @@ SC_execute(StatementClass *self)
 					 qi.fetch_size, SC_cursor_name(self));
 			qryi = &qi;
 			appendq = fetch;
+			qflag &= (~READ_ONLY_QUERY); /* must be a SAVEPOINT after DECLARE */
 		}
 		res = SC_get_Result(self);
 		if (self->curr_param_result && res)
@@ -2154,7 +2158,7 @@ inolog("!!! numfield=%d field_type=%u\n", QR_NumResultCols(res), QR_get_field_ty
 			qi.cursor = SC_cursor_name(self);
 			qi.cache_size = qi.row_size = ci->drivers.fetch_max;
 			SPRINTF_FIXED(fetch, "fetch " FORMAT_LEN " in \"%s\"", qi.fetch_size, SC_cursor_name(self));
-			res = CC_send_query(conn, fetch, &qi, qflag, SC_get_ancestor(self));
+			res = CC_send_query(conn, fetch, &qi, qflag | READ_ONLY_QUERY, SC_get_ancestor(self));
 			if (NULL != res)
 				SC_set_Result(self, res);
 		}
@@ -2346,6 +2350,7 @@ static BOOL
 RequestStart(StatementClass *stmt, ConnectionClass *conn, const char *func)
 {
 	BOOL	ret = TRUE;
+	unsigned int	svpopt = 0;
 
 #ifdef	_HANDLE_ENLIST_IN_DTC_
 	if (conn->asdum)
@@ -2358,7 +2363,9 @@ RequestStart(StatementClass *stmt, ConnectionClass *conn, const char *func)
 	}
 	if (CC_started_rbpoint(conn))
 		return TRUE;
-	if (SQL_ERROR == SetStatementSvp(stmt))
+	if (SC_is_readonly(stmt))
+		svpopt |= SVPOPT_RDONLY;
+	if (SQL_ERROR == SetStatementSvp(stmt, svpopt))
 	{
 		char	emsg[128];
 
@@ -2403,14 +2410,16 @@ libpq_bind_and_exec(StatementClass *stmt)
 	if (!RequestStart(stmt, conn, func))
 		return NULL;
 
+#ifdef	NOT_USED
 	if (CC_is_in_trans(conn) && !CC_started_rbpoint(conn))
 	{
-		if (SQL_ERROR == SetStatementSvp(stmt))
+		if (SQL_ERROR == SetStatementSvp(stmt, 0))
 		{
 			SC_set_error_if_not_set(stmt, STMT_INTERNAL_ERROR, "internal savepoint error in build_libpq_bind_params", func);
 			return NULL;
 		}
 	}
+#endif /* NOT_USED */
 
 	/* 1. Bind */
 	mylog("%s: bind stmt=%p\n", func, stmt);
diff --git a/statement.h b/statement.h
index 9da7712..e936455 100644
--- a/statement.h
+++ b/statement.h
@@ -281,6 +281,7 @@ struct StatementClass_
 	SQLLEN		exec_current_row;
 
 	unsigned char	miscinfo;
+	unsigned char	execinfo;
 	po_ind_t	updatable;
 	SQLLEN		diag_row_count;
 	char		*load_statement; /* to (re)load updatable individual rows */
@@ -424,10 +425,14 @@ enum
 #define SC_set_fetchcursor(a)	((a)->miscinfo |= (1L << 1))
 #define SC_no_fetchcursor(a)	((a)->miscinfo &= ~(1L << 1))
 #define SC_is_fetchcursor(a)	(((a)->miscinfo & (1L << 1)) != 0)
-#define SC_set_with_hold(a)	((a)->miscinfo |= (1L << 3))
-#define SC_set_without_hold(a)	((a)->miscinfo &= ~(1L << 3))
-#define SC_is_with_hold(a)	(((a)->miscinfo & (1L << 3)) != 0)
-#define SC_miscinfo_clear(a)	((a)->miscinfo &= (1L << 3))
+#define SC_miscinfo_clear(a)	((a)->miscinfo = 0)
+#define SC_set_with_hold(a)	((a)->execinfo |= 1L)
+#define SC_set_without_hold(a)	((a)->execinfo &= (~1L))
+#define SC_is_with_hold(a)	(((a)->execinfo & 1L) != 0)
+#define SC_set_readonly(a)	((a)->execinfo |= (1L << 1))
+#define SC_set_no_readonly(a)	((a)->execinfo &= ~(1L << 1))
+#define SC_is_readonly(a)	(((a)->execinfo & (1L << 1)) != 0)
+#define SC_execinfo_clear(a)	(((a)->execinfo = 0)
 #define	STMT_HAS_OUTER_JOIN	1L
 #define	STMT_HAS_INNER_JOIN	(1L << 1)
 #define SC_has_join(a)		(0 != (a)->join_info)
@@ -533,7 +538,7 @@ int		enqueueNeedDataCallback(StatementClass *self, NeedDataCallfunc, void *);
 RETCODE		dequeueNeedDataCallback(RETCODE, StatementClass *self);
 void		cancelNeedDataState(StatementClass *self);
 int		StartRollbackState(StatementClass *self);
-RETCODE		SetStatementSvp(StatementClass *self);
+RETCODE		SetStatementSvp(StatementClass *self, unsigned int option);
 RETCODE		DiscardStatementSvp(StatementClass *self, RETCODE, BOOL errorOnly);
 
 QResultClass *ParseAndDescribeWithLibpq(StatementClass *stmt, const char *plan_name, const char *query_p, Int2 num_params, const char *comment, QResultClass *res);