From 7cbff48f5782d1f7f844678e6b785aeb419b0c47 Mon Sep 17 00:00:00 2001
From: Milian Wolff <mail@milianw.de>
Date: Mon, 1 Dec 2014 11:59:12 +0100
Subject: [PATCH 18/30] Optimize: Skip value condition on invalid flags.

HandlerHelper::itemWithFlagsCount gets called quite often apparently
and I noticed that it was relatively slow from the Query Debugger
in Akonadi Console. EXPLAIN'ing the query showed that it was using
a slow-path for the WHERE FOO AND (BAR OR ASDF) condition. Here,
ASDF was always id = -1, the id of the $IGNORED flag, which
I apparently don't have. Getting rid of that condition simplifies
the query to WHERE FOO AND BAR, which is apparently much better
optimizable. Before, the query often showed a runtime of ~15ms.
Now it is down to ~9ms.

REVIEW: 121306
---
 server/src/handlerhelper.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/server/src/handlerhelper.cpp b/server/src/handlerhelper.cpp
index 634a26c..82347b4 100644
--- a/server/src/handlerhelper.cpp
+++ b/server/src/handlerhelper.cpp
@@ -123,6 +123,10 @@ int HandlerHelper::itemWithFlagsCount( const Collection &col, const QStringList
   // it hits an in-memory cache.
   Q_FOREACH ( const QString &flag, flags ) {
     const Flag f = Flag::retrieveByName( flag );
+    if (!f.isValid()) {
+      // since we OR this condition, we can skip invalid flags to speed up the query
+      continue;
+    }
     cond.addValueCondition( PimItemFlagRelation::rightFullColumnName(), Query::Equals, f.id() );
   }
   qb.addCondition( cond );
-- 
2.1.0