如何比较没有缓存的neo4j查询的性能？ [英] How to compare performance on neo4j queries without cache?

问题描述

我一直在尝试比较neo4j中的查询性能。

I've been trying to compare queries performance in neo4j.

为了提高查询效率，我添加了索引，使用配置文件分析了结果，在使用USING INDEX时尝试做同样的事情。

In order to make the queries more efficient, I added index, analysed the result using profile, and tried doing the same while using the USING INDEX.

在大多数查询中，DB Hits使用第二个选项（使用USING INDEX）要好得多，行数相同或者更少，但时间性能似乎不可靠：在几个查询中添加USING INDEX虽然性能参数（db hits& rows）更好，但通过重新执行查询得到的效果要好得多。

On most queries, DB Hits were much better using the second option (with the USING INDEX), rows were the same or less, but the time performance seems not to be reliable: on several queries adding the USING INDEX was slower though the better performance parameters (db hits & rows)and times got much better by re-executing a query.

为了阻止缓存的干扰，转到属性文件，将neo4j.properties中的cache_type更改为none并重新启动neo，但它仍然看起来像是同一个查询的结果每次都会更快（直到某一点）。

In order to stop the cache's interfering, went to the the properties file, changed the cache_type in the neo4j.properties to none and restarted neo, but it still seems like the results of the same query comes faster each time (until a certain point).

测试它的最佳方法是什么？

What will be the best way to test it?

推荐答案

Neo4j有（最多2.2.x）a 两层缓存架构。使用 cache_type = node ，您只需切换对象缓存。要禁用页面缓存，可以使用 dbms.pagecache.memory = 0 。但是，如果禁用所有缓存，则基本上可以测量IO子系统的速度，因为每个查询都会进入裸机并从光盘读取。

Neo4j has (up to 2.2.x) a two layered cache architecture. With cache_type=node you switch of just the object cache. To disable page cache, you can use dbms.pagecache.memory=0. However if all caches are disabled you basically measure the speed of your IO subsystem since every query goes down to the bare metal and reads from disc.

我建议采用不同的方法：启用两个缓存并运行您想要多次比较的查询以加热缓存。对温暖的缓存进行测量，因为这更接近真实的生产场景。

I recommend a different approach: enable both caches and run the queries you want to compare multiple times to warm up caches. Take measurement on warmed cache since this is much closer to a real production scenario.

在旁注：在Neo4j 2.3中，对象缓存将消失，我们只有页面缓存。

On a side note: in Neo4j 2.3 the object cache will go away and we just have the page cache.

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