| Subject: | Potential loss of async result in dbd_st_execute. |
At least the 2.17.1 dbd_st_execute unconditionally PQclears any existing
result still attached to a statement handle before starting a new query
on it. This is not necessary when starting an asynchronous query because
the routine will then return without assigning a new value to the
imp_sth->result pointer and could be considered wrong because a caller
might start another asychronous query before examining the result of
the last one and the 'early PQclear' would then cause the result of the
last query which was executed to be thrown away before any of its data
was retrieved by an application. The attached patch works around this by
not clearing the old result if an asynchronous query is to be started.
It will be cleared the next time pg_db_result fetches a new result
for the statement.
| Subject: | patch.txt |
--- DBD-Pg/dbdimp.c 3 Jun 2010 13:28:17 -0000 1.1.1.3
+++ DBD-Pg/dbdimp.c 14 Jun 2010 14:27:45 -0000 1.1.1.3.2.1
@@ -2910,8 +2910,13 @@
}
}
- /* clear old result (if any) */
- if (imp_sth->result) {
+ /*
+ Clear old result (if any), except if starting the
+ query asynchronously. Old async results will be
+ deleted implicitly the next time pg_db_result is
+ called.
+ */
+ if (imp_sth->result && !(imp_sth->async_flag & PG_ASYNC)) {
TRACE_PQCLEAR;
PQclear(imp_sth->result);
imp_sth->result = NULL;