![]() ![]() Along about Solr 4.7 or so support made its way into Solr so you could configure these in solrconfig.xml. There’s been a new suggester in town for a while, thanks to some incredible work by some of the Lucene committers. More on these suggester implementations later. One note, the first two above are from an FST-based suggester, and the second two are are from an AnalyzingInfix suggester. This blog is about how to configure the suggesters to get this kind of response, and also talk about some of the “gotchas” that exist. The Solr/Lucene suggester component can make this happen quickly enough to satisfy very demanding situations. The screen shot below shows an example of faceting from the CNET Web site (CBS Interactive Inc.), which was the first site to use Solr.How would you like to have your user type “energy”, and see suggestions like: Faceting makes it easy for users to explore search results on sites such as movie sites and product review sites, where there are many categories and many items within a category. Within each category, Solr reports on the number of hits for relevant term, which is called a facet constraint. To help users zero in on the content they’re looking for, Solr supports grouping search results to aid further exploration.įaceting is the arrangement of search results into categories (which are based on indexed terms). ![]() ![]() Popular search engines such as Google and Yahoo! return snippets in their search results: 3-4 lines of text offering a description of a search result. ![]() Search responses can also be configured to include snippets (document excerpts) featuring highlighted text. Solr includes a rich set of search parameters for controlling how terms are highlighted. Highlighting can make it easier to find relevant passages in long documents returned in a search. Filter queries perform queries at search time against data already in the index, while analysis filters, such as Tokenizers, parse content for indexing, following specified rules).Ī search query can request that certain terms be highlighted in the search response that is, the selected terms will be displayed in colored boxes so that they "jump out" on the screen of search results. (Despite their similar names, query filters are not related to analysis filters. Because Solr allocates a separate cache for filter queries, the strategic use of filter queries can improve search performance. As part of a search response, a filter query runs a query against the entire index and caches the results. Search parameters may also specify a filter query. Parameters for controlling the presentation of the query response, such as specifying the order in which results are to be presented or limiting the response to particular fields of the search application’s schema. Parameters for fine-tuning the query by increasing the importance of particular strings or fields, by applying Boolean logic among the search terms, or by excluding content from the search results Search strings-that is, terms to search for in the index In addition, there are common query parameters that are accepted by all query parsers. It also includes several additional features. The Extended DisMax query parser is an improved version of DisMax that handles the full Lucene query syntax while still tolerating syntax errors. The DisMax query parser is designed to provide an experience similar to that of popular search engines such as Google, which rarely display syntax errors to users. The standard query parser’s syntax allows for greater precision in searches, but the DisMax query parser is much more tolerant of errors. Solr also includes the DisMaxquery parser, and the Extended DisMax (eDisMax) query parser. Solr’s default query parser is known as the Standard Query Parser,or more commonly just the "lucene" query parser. Different query parsers support different syntax. To process a search query, a request handler calls a query parser, which interprets the terms and parameters of a query. In addition, applications can be configured to allow users to override the default selection in preference of a different request handler. Search applications select a particular request handler by default. Some are designed for processing search queries, while others manage tasks such as index replication. Solr supports a variety of request handlers. A request handler is a Solr plug-in that defines the logic to be used when Solr processes a request. When a user runs a search in Solr, the search query is processed by a request handler. To understand the extent of this flexibility, it’s helpful to begin with an overview of the steps and components involved in a Solr search. Solr offers a rich, flexible set of features for search. ![]()
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