On 1/4/2016 4:11 PM, Don Bosco Durai wrote: > Erick, I am using SolrCloud with solrconfig.xml configured with autoCommit. > And I also read somewhere that explicit commit is not recommended in > SolrCloud mode. Regarding auto warm, my server has/was been running for a > while.
Since 4.0, autoCommit with openSearcher set to false is highly recommended, no matter what your needs are regarding visibility, and whether or not you're running in cloud mode. The exact interval to use is a subject for vigorous debate. A common maxTime value that you will see for autoCommit is 15 seconds (15000). I personally feel this is too frequent, but many people use that value with no problems. I use five minutes (300000) in my own config, but over the course of those five minutes, there's not much in the way of updates, so the log replay will take very little time. Using autoCommit with openSearcher set to false takes care of transaction log rotation, it doesn't do ANYTHING for document visibility. The issue of how to handle document visibility will depend on exactly how you use your index. Do not worry about whether the index is SolrCloud or not for this topic. One way of handling document visibility is to use autoSoftCommit (available since 4.0) in your config ... with maxTime set to the longest possible interval you can stand. My personal recommendation is to never set that interval shorter than one minute (60000). Push back if you are told that documents must be visible faster than that. If you use autoSoftCommit, you won't need explicit commits from your indexing application. Another way to handle document visibility is the commitWithin parameter on each update request. This is similar to autoSoftCommit, but gets set on the update request. Just like autoSoftCommit, I would not recommend a value less than one minute, and if this parameter is used on all updates, you will never need an explicit commit. Using autoSoftCommit or commitWithin is a good option if there are many clients/threads sending changes to the same index or the indexing happens in bursts where the update size is wildly different and completely unpredictable. The final way to handle document visibility is explicit commits. When you want changes to be visible, you send a commit, hard or soft, with openSearcher set to true (this is the default for this parameter), and a short time later, all changes sent before that commit will become visible. This is how I handle my own index. This is a good option if all indexing is coming from a single source and that source has complete control over all indexing operations. One of the strong goals with commits is to avoid them happening too frequently, so they don't overlap, and so the machine is spending less time handling commits than it spends either idle or handling queries. Here's a blog post with more detail. The blog post says "SolrCloud" but almost all of it is equally applicable to Solr 4.x and 5.x indexes that are not running in cloud mode: http://lucidworks.com/blog/understanding-transaction-logs-softcommit-and-commit-in-sorlcloud/ Thanks, Shawn
