If there are percolator queries containing `range` queries with ranges based on the current time then this can lead to incorrect results if the `percolate` query gets cached. These ranges are changing each time the `percolate` query gets executed and if this query gets cached then the results will be based on how the range was at the time when the `percolate` query got cached.
The ExtractQueryTermsService has been renamed `QueryAnalyzer` and now only deals with analyzing the query (extracting terms and deciding if the entire query is a verified match) . The `PercolatorFieldMapper` is responsible for adding the right fields based on the analysis the `QueryAnalyzer` has performed, because this is highly dependent on the field mappings. Also the `PercolatorFieldMapper` is responsible for creating the percolate query.
Significant changes:
* AbstractQueryTestCase has moved to the test framework module, in order for query builder tests in modules and plugins
* Added support to AbstractQueryTestCase to register plugins
* Lift the restriction that only one percolator could be added per index. This validation existed in MapperService, but because the percolator moved to a module it could no longer exist there. Instead of bringing it back it was removed. This validation existed since the percolator cache only supported one percolator query per document, since the percolator cache has been removed this restriction could removed as well.
* While moving percolator tests to the new module, also removed a couple of tests for the deprecated percolate and mpercolate api. These APIs are now sugar APIs for bwc and rediect to the searvh and msearvh APIs. Some tests were still testing as if percolate and mpercolate API did the percolation, but this no longer the case and these tests could be removed.
Before 5.0 for it was required that the percolator queries were cached in jvm heap as Lucene queries for two reasons:
1) Performance. The percolator evaluated all percolator queries all the time. There was no pre-selecting queries that are likely to match like we have today.
2) Updates made to percolator queries were visible in realtime, Today these changes are visible in near realtime. So updating no longer requires the percolator to have the queries in jvm heap.
So having the percolator queries in jvm heap via the percolator cache is now less attractive. Especially when there are many percolator queries then these queries can consume many GBs of jvm heap.
Removing the percolator cache does make the percolate query slower compared to how the execution time in 5.0.0-alpha1 and alpha2, but it is still faster compared to 2.x and before.
* Added an extra `field` parameter to the `percolator` query to indicate what percolator field should be used. This must be an existing field in the mapping of type `percolator`.
* The `.percolator` type is now forbidden. (just like any type that starts with a `.`)
This only applies for new indices created on 5.0 and later. Indices created on previous versions the .percolator type is still allowed to exist.
The new `percolator` field type isn't active in such indices and the `PercolatorQueryCache` knows how to load queries from these legacy indices.
The `PercolatorQueryBuilder` will not enforce that the `field` parameter is of type `percolator`.
Also replaced the PercolatorQueryRegistry with the new PercolatorQueryCache.
The PercolatorFieldMapper stores the rewritten form of each percolator query's xcontext
in a binary doc values field. This make sure that the query rewrite happens only during
indexing (some queries for example fetch shapes, terms in remote indices) and
the speed up the loading of the queries in the percolator query cache.
Because the percolator now works inside the search infrastructure a number of features
(sorting fields, pagination, fetch features) are available out of the box.
The following feature requests are automatically implemented via this refactoring:
Closes#10741Closes#7297Closes#13176Closes#13978Closes#11264Closes#10741Closes#4317
Martijn van Groningen
Clinton Gormley