#SEAMLESS SYNONYM FULL#

With no quotes, and your SynonymGraphFilter expands dns to also search for domain name system, then the query parser will first build up the whole token graph after analyzing your query, and then enumerate the separate paths through the graph:ДЄnd will then separately analyze those two strings to produce sub-queries, taking their union using SHOULD clauses in a BooleanQuery. These fixes, combined, enable you to apply multi-token synonyms at search-time and achieve accurate results. In Elasticsearch, the match_query, query_string and simple_query_stringВ queries will all correctly handle a token graph. The query parser (specifically the QueryBuilder base class) now watches the PositionLengthAttribute and computes all paths through the graph when any token has a value greater than 1.

The third query parser fix is to detect when the query-time analyzer produced a graph, and create accurate queries as a result, also first added in Lucene 6.4.0. These simplifications to the complex logic in QueryBuilder are also an important precursor. This change empowers the query-time analyzer to see multiple tokens as a single string instead of seeing each token separately. Be sure to call setSplitOnWhitespace(false) since the whitespace splitting isВ still enabled by default to preserve backwards compatibility. First, the classic query parser had to stop pre-splitting incoming query text at whitespace, fixed (after years of controversy!) in Lucene 6.2.0. The second set of vital improvements is to the query parsers.

#SEAMLESS SYNONYM FULL#

If for some reason you really need exactly the same behavior as the old SynonymFilter then you should create a SynonymGraphFilter followed by a FlattenGraphFilter, but just remember that FlattenGraphFilter necessarily throws something (the full graph structure) away! Along with this we've also added a new FlattenGraphFilter, to squash any graph token stream for indexing. This new synonym filter produces a correct graph in all cases (except for any exciting bugs!), whether your inserted synonym is a single token or multiple tokens. The first big change is the addition of SynonymGraphFilter, replacing the now-deprecated SynonymFilter. This has been a longstanding, complex, glaring and embarrassing limitation of synonyms with Lucene, resulting in multiple Jira issues, long discussions on Lucene's users list and multiple complex blog posts describing hairy, partial workarounds.ДЇinally, as of Lucene 6.4.0, included in Elasticsearch 5.2.0, we have a clean solution, as long as you apply synonyms at search-time instead of index-time. Then even the tokens produced by SynonymFilter would already be flattened, before indexing! Worse, if your synonym had inserted more than one token, such as reversing the above collapsing rule into an expanding one: Similarly, the phrase query 'dns name system' should not match this document, but will! For example, the phrase query 'dns is fragile' will fail to match this document yet it should. Of course, this makes some queries buggy. However, once you add this document to a Lucene index, some of the graph structure is lost because Lucene ignores the PositionLengthAttribute, which states where a given token should end, and effectively flattens your token graph to this: The resulting token graph from Lucene, as encoded using PositionIncrementAttribute and PositionLengthAttribute attributes, looks like this: Long ago I described how the tokens Lucene produces during text analysis really describe a graph which is a good fit for the complex structure of the natural languages we humans speak and write.

Seamless synonym