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