In psql, when running a SELECT query using a cursor, flush the query

output after each FETCH. This ensures that incremental results are
available to clients that are executing long-running SELECT queries
via the FETCH_COUNT feature.

1 files changed, 6 insertions, 0 deletions

diff --git a/src/bin/psql/common.c b/src/bin/psql/common.c
index ebd6aee017..25273ccc99 100644
--- a/src/bin/psql/common.c
+++ b/src/bin/psql/common.c
@@ -1076,6 +1076,12 @@ ExecQueryUsingCursor(const char *query, double *elapsed_msec)
 
 		printQuery(results, &my_popt, pset.queryFout, pset.logfile);
 
+		/*
+		 * Make sure to flush the output stream, so intermediate
+		 * results are visible to the client immediately.
+		 */
+		fflush(pset.queryFout);
+
 		/* after the first result set, disallow header decoration */
 		my_popt.topt.start_table = false;
 		my_popt.topt.prior_records += ntuples;