Custom SOLR Search Components - 2 Dev Tricks
I've been building some custom search components for SOLR lately, so wanted to share a couple of things I learned in the process. Most likely this is old hat to people who have been doing this for a while, but thought I'd share, just in case it benefits someone...
Passing State
In a previous post, I described a custom SOLR search handler returns layered search results for a given query term (and optional filters). As I went further, though, I realized that I needed to return information relating to facets and category clusters as well. Of course, I could have added this stuff into the handler itself, but splitting the logic across a chain of search components seemed to be more preferable, readability and reusability wise, so I went that route.
So the first step was to refactor my custom SearchHandler into a SearchComponent. Not much to do there, except to subclass SearchComponent instead of RequestHandlerBase and move the handleRequestBody(SolrQueryRequest,SolrQueryResponse) to a process(ResponseBuilder) method. The request and response objects are accessible from the ResponseBuilder as properties, ie, ResponseBuilder.req and ResponseBuilder.rsp. I then declared this component and an enclosing handler in solrconfig.xml, something like this:
1 |
<!-- this used to be my search handler --> |
I've also added a second component to the chain above (just so I don't have to show this snippet again later), hope its not too confusing. Obviously there can be multiple components before and after my search handler turned search component, but for the purposes of this discussion, I'll keep things simple and just concentrate on this one other component and pretend that it has multiple unique (and pertinent) requirements.
Now, assume that the second component needed data that was already available, or can be easily generated by component1. Its actually true in my case, since I needed a BitSet of document ids in the search results in my second component, which I could easily get by collecting them while looping through the SolrDocumentList of results in my first component. So it seemed kind of wasteful to compute this again. So I updated this snippet of code in component1's process() method (what used to be my handleRequestBody() method):
1 |
public void process(ResponseBuilder rb) throws IOException { |
In my next component (component2), I simply grab the OpenBitSet data structure by name from the NamedList, use them to generate the result for this component, stick the result back into the response, and discard the temporary data. The last is so that the data does not appear on the response XML (for both aesthetic and performance reasons).
1 |
public void process(ResponseBuilder rb) throws IOException { |
Before I did this, I investigated if I could subclass the XmlResponseWriter to ignore NamedLists with "hidden" names (ie names prefixed with underscore), but the XmlResponseWriter calls XMLWriter which does the actual XML generation, and XMLWriter is final (at least in SOLR 1.4.1). Good thing too, forced me to look for and find a simpler solution :-).
So there you have it - a simple way to pass data between components in a SOLR Search RequestHandler. Note that it does mean that component2 is always dependent on component1 (or some other component that produces the same data) upstream to it, so these components are no longer truly reusable pieces of code. But this can be useful if you really need it and you document the requirement (or complain about it if not met, as I've done here).
Reacting to a COMMIT
The second thing I needed to do in component2 was to give it some reference data that it would need to compute its results. The reference data is generated from the contents of the index, and the generation is fairly heavyweight, so you don't want to do this on every request.
Now one of the cool things about SOLR is its built-in incremental indexing feature (one of the main reasons we considered using SOLR in the first place), so you can POST data to a running SOLR instance followed by a COMMIT, and voila: your searcher re-opens with the new data.
Of course, this also means that if we want to provide accurate information, the reference data should be regenerated whenever the searcher is reopened. The way I went about doing this is mostly derived from how the SpellCheckerComponent does it, in order to regenerate its dictionaries -- by hooking into the SOLR event framework.
To do this, my component2 implements SolrCoreAware in addition to extending SearchComponent. This requires me to implement the inform(SolrCore) method, which is invoked by SOLR after the init(NamedList) but before prepare(ResponseBuilder) and process(ResponseBuilder). In the inform(SolrCore) method, I register a listener for the firstSearcher and newSearcher events (described in more detail here).
I then build the inner listener class, which implements SolrEventListener, which requires me to provide implementations for newSearcher() and postCommit() methods. Since my listener is a query-side listener, I provide an empty implementation for postCommit(). The newSearcher() method contains the code to generate the reference sets. Here is the relevant snippet of code from the component.
1 |
public class MyComponent2 extends SearchComponent implements SolrCoreAware { private RefData refdata; // this needs to be regenerated on COMMIT @Override |
Notice that I have registered the listener to listen on both firstSearcher and newSearcher events. This way, it gets called on SOLR startup (reacting to a firstSearcher event), and again each time the searcher is reopened (reacting to a newSearcher event).
One other thing... since the generation of RefData takes some time, its best to have the listener's newSearcher method build a copy and then repopulate the refdata variable from the copy, that way the component continues to use the old data until the new one is available.
And thats pretty much it for today. Till next time.
http://sujitpal.blogspot.com/2011/04/custom-solr-search-components-2-dev.html
Custom SOLR Search Components - 2 Dev Tricks的更多相关文章
- How to Reuse Old PCs for Solr Search Platform?
家裡或公司的舊電腦不夠力? 效能慢到想砸爛它們? 朋友或同事有電腦要丟嗎? 我有一個廢物利用的方法, 我收集了四台舊電腦, 組了一個Fully Distributed Mode的Hadoop Clus ...
- solr search基础知识(控制符及其参数)
1.^ 控制符 (1)查询串上用^ 搜索: 天后王菲,如果希望将王菲的相关度加大,用^控制符. 天后 王菲^10.5 结果就会将含有王菲的document权重加大分数提高,排序靠前,10.5为权重 ...
- Solr Cloud - SolrCloud
关于 Solr Cloud Zookeeper 入门,介绍 原理 原封不动转自 http://wiki.apache.org/solr/SolrCloud/ ,文章的内存有些过时,但是了解原理. Th ...
- Solr: a custom Search RequestHandler
As you know, I've been playing with Solr lately, trying to see how feasible it would be to customize ...
- Importing/Indexing database (MySQL or SQL Server) in Solr using Data Import Handler--转载
原文地址:https://gist.github.com/maxivak/3e3ee1fca32f3949f052 Install Solr download and install Solr fro ...
- Solr 6.7学习笔记(03)-- 样例配置文件 solrconfig.xml
位于:${solr.home}\example\techproducts\solr\techproducts\conf\solrconfig.xml <?xml version="1. ...
- Solr基础知识二(导入数据)
上一篇讲述了solr的安装启动过程,这一篇讲述如何导入数据到solr里. 一.准备数据 1.1 学生相关表 创建学生表.学生专业关联表.专业表.学生行业关联表.行业表.基础信息表,并创建一条小白的信息 ...
- Solr 02 - 最详细的solrconfig.xml配置文件解读
目录 1 luceneMatchVersion - 指定Lucene版本 2 lib - 配置扩展jar包 3 dataDir - 索引数据路径 4 directoryFactory - 索引存储工厂 ...
- solr 5.3.1安装配置
1.下载Solr5.3.1 http://mirror.bit.edu.cn/apache/lucene/solr/5.3.1/ wget http://mirror.bit.edu.cn/apach ...
随机推荐
- JavaScript数据类型的检测
主要有一下四种方法: 1.typeof 2.instanceof 3.constructor 4.Object.prototype.toString.call() 1.typeof 不能具体细分是什么 ...
- C# 命名空间(Namespace)
命名空间的设计目的是提供一种让一组名称与其他名称分隔开的方式.在一个命名空间中声明的类的名称与另一个命名空间中声明的相同的类的名称不冲突. 也即是不同的命名空间可以有相同的类名
- 你所不知道的javascript数组特性
工作中,我们经常使用js的数组,但是,下面的东西你见过吗? 1,文本下标: var a=[]; a[-1]=1; 你想过数组的下标为负数的情况吗?我们对数组的下标规定从0开始.但是上面那么写也还是可以 ...
- leetcode671
class Solution { public: vector<int> V; void postTree(TreeNode* node) { if (node != NULL) { V. ...
- Selinux相关
SELinux相关的工具 /usr/bin/setenforce 修改SELinux的实时运行模式 setenforce 1 设置SELinux 成为enforcing模式 setenforce 0 ...
- 使用ExitProcess()结束本进程、TerminateProcess 结束进程
进程只是提供了一段地址空间和内核对象,其运行时通过在其地址空间内的主线程来体现的.当主线程的进入点函数返回时,进程也就随之结束.这种进程的终止方式是进程的正常退出,进程中的所有线程资源都能够得到正确的 ...
- Git(三):Git 使用规范流程
转:http://www.ruanyifeng.com/blog/2015/08/git-use-process.html 团队开发中,遵循一个合理.清晰的Git使用流程,是非常重要的. 否则,每个人 ...
- Java并发之AQS详解(转)
一.概述 谈到并发,不得不谈ReentrantLock:而谈到ReentrantLock,不得不谈AbstractQueuedSynchronized(AQS)! 类如其名,抽象的队列式的同步器,AQ ...
- C#窗体中将窗体按钮与键盘关联
当击了某个按钮相当于是按了某个键盘上按键 private void btnPre_Click(object sender, EventArgs e) { this.treeView1.Focu ...
- 启动日志中就出现[java:comp/env/spring.liveBeansView.mbeanDomain] not found这个日志
今天在做一个dubbo服务端的时候,启动成功,dubbo也注册成功,但是启动日志中就出现[java:comp/env/spring.liveBeansView.mbeanDomain] not fou ...