postgres.git / summary / log / commit / refs

commit    756e221db610f333649385f7fef96e7e9e23ed71
Author:   Fujii Masao <fujii@postgresql.org>
Date:     Tue Jul 26 07:00:18 2022 +0000

    Reduce overhead of renaming archive status files.
    
    Presently, archive status files are durably renamed from .ready to
    .done to indicate that a file has been archived.  Persisting this
    rename to disk accounts for a significant amount of the overhead
    associated with archiving.  While durably renaming the file
    prevents re-archiving in most cases, archive commands and libraries
    must already gracefully handle attempts to re-archive the last
    archived file after a crash (e.g., a crash immediately after
    archive_command exits but before the server renames the status
    file).
    
    This change reduces the amount of overhead associated with
    archiving by using rename() instead of durable_rename() to rename
    the archive status files.  As a consequence, the server is more
    likely to attempt to re-archive files after a crash, but as noted
    above, archive commands and modules are already expected to handle
    this.  It is also possible that the server will attempt to re-
    archive files that have been removed or recycled, but the archiver
    already handles this, too.
    
    Author: Nathan Bossart
    Reviewed-by: Kyotaro Horiguchi, Fujii Masao
    Discussion: https://postgr.es/m/20220222011948.GA3850532@nathanxps13


 src/backend/postmaster/pgarch.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/src/backend/postmaster/pgarch.c b/src/backend/postmaster/pgarch.c
index 25e31c42e16..6ce361707d7 100644
--- a/src/backend/postmaster/pgarch.c
+++ b/src/backend/postmaster/pgarch.c
@@ -745,7 +745,19 @@ pgarch_archiveDone(char *xlog)
 
 	StatusFilePath(rlogready, xlog, ".ready");
 	StatusFilePath(rlogdone, xlog, ".done");
-	(void) durable_rename(rlogready, rlogdone, WARNING);
+
+	/*
+	 * To avoid extra overhead, we don't durably rename the .ready file to
+	 * .done.  Archive commands and libraries must gracefully handle attempts
+	 * to re-archive files (e.g., if the server crashes just before this
+	 * function is called), so it should be okay if the .ready file reappears
+	 * after a crash.
+	 */
+	if (rename(rlogready, rlogdone) < 0)
+		ereport(WARNING,
+				(errcode_for_file_access(),
+				 errmsg("could not rename file \"%s\" to \"%s\": %m",
+						rlogready, rlogdone)));
 }
 
 


[parent: 27e0ee57f68d]