Copy the INSERT query in postgres_fdw

When executing the INSERT with batching, we may need to rebuild the
query when the batch size changes, in which case we pfree the current
string. We must not release the original string, stored in fdw_private,
because that may be needed in EXPLAIN ANALYZE. So make copy of the SQL,
but only for INSERT queries.

Reported-by: Pavel Stehule
Discussion: https://postgr.es/m/CAFj8pRCL_Rjw-MCR6J7VX9OF7MR6PA5K8qUbrMvprW_e-aHkfQ%40mail.gmail.com

diff --git a/contrib/postgres_fdw/postgres_fdw.c b/contrib/postgres_fdw/postgres_fdw.c
index 8bcdc8d6160dcd4329ee2cc16aafa0fb80e79a3a..4ff58d9c2756ce7a22b188e2aacd4b7aefe52ccb 100644 (file)
--- a/contrib/postgres_fdw/postgres_fdw.c
+++ b/contrib/postgres_fdw/postgres_fdw.c
@@ -3903,7 +3903,10 @@ create_foreign_modify(EState *estate,
    /* Set up remote query information. */
    fmstate->query = query;
    if (operation == CMD_INSERT)
+   {
+       fmstate->query = pstrdup(fmstate->query);
        fmstate->orig_query = pstrdup(fmstate->query);
+   }
    fmstate->target_attrs = target_attrs;
    fmstate->values_end = values_end;
    fmstate->has_returning = has_returning;