(2013/09/05 0:04), Andres Freund wrote:
> I'd vote for adding zeroing *after* the fallocate() first.
+1, with FALLOC_FL_KEEP_SIZE flag.
At least, fallocate with FALLOC_FL_KEEP_SIZE flag is faster than nothing in my
developing sorted checkpoint. I adopted it to relation file, so I don't know
about WAL file.
With FALLOC_FL_KEEP_SIZE flag does not change file size and not do zero fill. It
seems to only get continuous physical disk space in file system.
Here is draft patch.
Regards,
--
Mitsumasa KONDO
NTT Open Source Software Center
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index dc47c47..85b582c 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -3409,6 +3409,10 @@ XLogFileInit(XLogSegNo logsegno, bool *use_existent, bool use_lock)
(errcode_for_file_access(),
errmsg("could not create file \"%s\": %m", tmppath)));
+#if defined(HAVE_FALLOCATE)
+ fallocate(fd, FALLOC_FL_KEEP_SIZE, 0, XLogSegSize);
+#endif
+
/*
* Zero-fill the file. We have to do this the hard way to ensure that all
* the file space has really been allocated --- on platforms that allow
--
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