Activate low-volume optional logging during regression test runs.

Elaborated from an idea by Andres Freund.

src/test/regress/pg_regress.c

@@ -2456,12 +2456,12 @@ regression_main(int argc, char *argv[], init_function ifunc, test_function tfunc
 		}
 
 		/*
-		 * Adjust the default postgresql.conf as needed for regression
-		 * testing. The user can specify a file to be appended; in any case we
-		 * set max_prepared_transactions to enable testing of prepared xacts.
-		 * (Note: to reduce the probability of unexpected shmmax failures,
-		 * don't set max_prepared_transactions any higher than actually needed
-		 * by the prepared_xacts regression test.)
+		 * Adjust the default postgresql.conf for regression testing. The user
+		 * can specify a file to be appended; in any case we expand logging
+		 * and set max_prepared_transactions to enable testing of prepared
+		 * xacts.  (Note: to reduce the probability of unexpected shmmax
+		 * failures, don't set max_prepared_transactions any higher than
+		 * actually needed by the prepared_xacts regression test.)
 		 */
 		snprintf(buf, sizeof(buf), "%s/data/postgresql.conf", temp_install);
 		pg_conf = fopen(buf, "a");
@@ -2471,6 +2471,10 @@ regression_main(int argc, char *argv[], init_function ifunc, test_function tfunc
 			exit(2);
 		}
 		fputs("\n# Configuration added by pg_regress\n\n", pg_conf);
+		fputs("log_autovacuum_min_duration = 0\n", pg_conf);
+		fputs("log_checkpoints = on\n", pg_conf);
+		fputs("log_lock_waits = on\n", pg_conf);
+		fputs("log_temp_files = 128kB\n", pg_conf);
 		fputs("max_prepared_transactions = 2\n", pg_conf);
 
 		if (temp_config != NULL)