We wanted to share the information, that our first Elasticsearch book – the ElasticSearch Server was translated to Japanese and should be now available. Information about the book can be found at ASCII Index and the book can be purchased on Japanese Amazon site.
We would like to thank all the people who were involved in the translation process. Especially we would like to thank Jun Ohtani (@johtani, blog.johtani.info) who were in touch with us, submitted many corrections to the book (please see errata) and had to work with us Once again, thank you all!
The Mastering ElasticSearch book that was published in December 2013 included a chapter dedicated to improving user search experience. However, one of the topics didn’t made it into the book. Because of that we wanted to share this section of the book on the blog. We hope that you’ll find it useful.
Our publisher Packt Publishing is offering its ebooks and videos just for $5 till 3rd of January 2014 as the eBook Bonanza promotion. If you wanted to buy something published by Packt, like our ElasticSearch Server, Mastering ElasticSearch, Apache 4 Cookbook or Solr 3.1 Cookbook please go https://www.packtpub.com/ebookbonanza.
Its a nice promotion if you hesitated to buy any of the books from Packt Publishing, but remember that it end on 3rd of January, so not much time left.
Packt Publishing is giving everyone the chance to explore its entire catalog of eBooks and videos at 50% off in its biggest ever sale. During the event, anyone will be able to use the discount code COL50 at checkout for any eBooks or videos of their choice – as many times as they like until Thursday, 17th-Oct-2013. This is a great opportunity to buy both ElasticSearch Server and Mastering ElasticSearch books.
If you are interested please head to Packt Publishing home page, at https://www.packtpub.com/.
The Mastering ElasticSearch book that is going to be published in December 2013 (probable date, but may be available earlier) will include a chapter that is dedicated to extending ElasticSearch. However, one of the topics – the simplest one didn’t made it into the book. Because of that we wanted to share this section of the book on the blog. We hope that you’ll find it useful.
Till now, we didn’t talk about shard allocation process or ability to move shards around the cluster. If you recall what shard allocation is – the process of allocating shards to nodes which can happen during initial cluster start, during replicas allocation or when nodes are being removed or added to the cluster. However apart from the allocation mechanism control, sometimes it is crucial to be able to cancel shard allocation or move shards around inside the cluster. In order to do that ElasticSearch exposes the reroute API, which allows us to move shards, cancel their allocation and finally force the allocation. You can imagine a situation when you would like to take off a single node from your cluster for maintenance, but you have data on it and first you want to somehow move the data to some other node. This is where the reroute API can come in handy. So now, let’s discuss all the possibilities that give us.
ElasticSearch is designed to work with indices that are built of multiple shards and replicas and you probably have such indices in your cluster. Sometimes it may be handy to see which shard will the query be exectued at. Before ElasticSearch 0.90 you could run a query and check the stats to see that, but now we can use the Search Shards API. Let’s look on how we can use this API by using a simple example and queries that does and doesn’t use routing.
With the incoming release of ElasticSearch 0.90.3 we will get a new maintenance API, a one that is able to return cluster and node related information in plain text format, not in JSON. It can come useful when working with your cluster from command line – for example when you don’t want to analyze the whole JSON output, but you are only interested in some of the information returned. Let’s have a look how this API looks like.
In addition to the ability to control what value is taken into consideration when sorting on multi-valued fields, ElasticSearch 0.90.0.Beta1 introduced another sorting improvement – ability to sort on the basis of the fields inside the nested objects. We can chose a path, a filter that will narrow the nested objects, and like in the sort_mode property (just like in the post describing multi-valued fields sorting).