From 40e6862ae6f708d603df8b4d7ce4683991918ff2 Mon Sep 17 00:00:00 2001
From: Aaron Schulz <aschulz@wikimedia.org>
Date: Wed, 18 Jan 2017 14:39:23 -0800
Subject: [PATCH] Avoid master queries when old filter checks are viewed

Bug: T154554
Change-Id: I5ca7f0ea22c337c38083532291400df8c7db1e11
---
 includes/page/WikiPage.php | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/includes/page/WikiPage.php b/includes/page/WikiPage.php
index 920ba87806..d582d51bf6 100644
--- a/includes/page/WikiPage.php
+++ b/includes/page/WikiPage.php
@@ -2150,8 +2150,12 @@ class WikiPage implements Page, IDBAccessObject {
 				);
 			} else {
 				// Try to avoid a second parse if {{REVISIONID}} is used
-				$edit->popts->setSpeculativeRevIdCallback( function () {
-					return 1 + (int)wfGetDB( DB_MASTER )->selectField(
+				$dbIndex = ( $this->mDataLoadedFrom & self::READ_LATEST ) === self::READ_LATEST
+					? DB_MASTER // use the best possible guess
+					: DB_REPLICA; // T154554
+
+				$edit->popts->setSpeculativeRevIdCallback( function () use ( $dbIndex ) {
+					return 1 + (int)wfGetDB( $dbIndex )->selectField(
 						'revision',
 						'MAX(rev_id)',
 						[],
-- 
2.20.1