Report the current queries of all backends involved in a deadlock

(if they'd be visible to the current user in pg_stat_activity).

This might look like it's subject to race conditions, but it's actually
pretty safe because at the time DeadLockReport() is constructing the
report, we haven't yet aborted our transaction and so we can expect that
everyone else involved in the deadlock is still blocked on some lock.
(There are corner cases where that might not be true, such as a statement
timeout triggering in another backend before we finish reporting; but at
worst we'd report a misleading activity string, so it seems acceptable
considering the usefulness of reporting the queries.)

Original patch by Itagaki Takahiro, heavily modified by me.

1 files changed, 2 insertions, 1 deletions

diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 95589eb51e7..49fd149d55c 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -5,7 +5,7 @@
  *
  *	Copyright (c) 2001-2008, PostgreSQL Global Development Group
  *
- *	$PostgreSQL: pgsql/src/include/pgstat.h,v 1.71 2008/01/01 19:45:56 momjian Exp $
+ *	$PostgreSQL: pgsql/src/include/pgstat.h,v 1.72 2008/03/21 21:08:31 tgl Exp $
  * ----------
  */
 #ifndef PGSTAT_H
@@ -507,6 +507,7 @@ extern void pgstat_bestart(void);
 extern void pgstat_report_activity(const char *what);
 extern void pgstat_report_xact_timestamp(TimestampTz tstamp);
 extern void pgstat_report_waiting(bool waiting);
+extern const char *pgstat_get_backend_current_activity(int pid);
 
 extern void pgstat_initstats(Relation rel);