Percolator changes

Previously percolators were activated in real-time, i.e. as soon as they were indexed. Now, changes to the percolate query are visible in near-real time, as soon as the index has been refreshed. This change was required because, in indices created from 5.0 onwards, the terms used in a percolator query are automatically indexed to allow for more efficient query selection during percolation.

Percolator and multi percolate APIs have been deprecated and will be removed in the next major release. These APIs have been replaced by the percolate query that can be used in the search and multi search APIs.

The .percolator type can no longer be used to index percolator queries.

Instead a percolator field type must be configured prior to indexing percolator queries.

Indices with a .percolator type created on a version before 5.0.0 can still be used, but new indices no longer accept the .percolator type.

However it is strongly recommended to reindex any indices containing percolator queries created prior upgrading to Elasticsearch 5. By doing this the percolate query utilize the extracted terms the percolator field type extracted from the percolator queries and potentially execute many times faster.

The percolate query no longer modifies the mappings. Before the percolate API could be used to dynamically introduce new fields to the mappings based on the fields in the document being percolated. This no longer works, because these unmapped fields are not persisted in the mapping.

Documents with the .percolate type were previously excluded from the search response, unless the .percolate type was specified explicitly in the search request. Now, percolator documents are treated in the same way as any other document and are returned by search requests.

When percolating an existing document then also specifying a document as source in the percolate query is not allowed any more. Before the percolate API allowed and ignored the existing document.

The percolate stats have been removed. This is because the percolator no longer caches the percolator queries.

The percolator no longer accepts percolator queries containing range queries with ranges that are based on current time (using now).

Percolator queries that contain scripts (For example: script query or a function_score query script function) that have no explicit language specified will use the Painless scripting language from version 5.0 and up.

Scripts with no explicit language set in percolator queries stored in indices created prior to version 5.0 will use the language that has been configured in the script.legacy.default_lang setting. This setting defaults to the Groovy scripting language, which was the default for versions prior to 5.0. If your default scripting language was different then set the script.legacy.default_lang setting to the language you used before.

In order to make use of the new percolator field type all percolator queries should be reindexed into a new index. When reindexing percolator queries with scripts that have no explicit language defined into a new index, one of the following two things should be done in order to make the scripts work: * (Recommended approach) While reindexing the percolator documents, migrate the scripts to the Painless scripting language. * or add lang parameter on the script and set it the language these scripts were written in.

The percolator is no longer part of the core elasticsearch dependency. It has moved to the percolator module. Therefor when using the percolator feature from the Java client the new percolator module should also be on the classpath. Also the transport client should load the percolator module as plugin:

TransportClient transportClient = TransportClient.builder()
        .settings(Settings.builder().put("node.name", "node"))
        .addPlugin(PercolatorPlugin.class)
        .build();
transportClient.addTransportAddress(
        new InetSocketTransportAddress(new InetSocketAddress(InetAddresses.forString("127.0.0.1"), 9300))
);

The percolator and multi percolate related methods from the Client interface have been removed. These APIs have been deprecated and it is recommended to use the percolate query in either the search or multi search APIs. However the percolate and multi percolate APIs can still be used from the Java client.

Using percolate request:

PercolateRequest request = new PercolateRequest();
// set stuff and then execute:
PercolateResponse response = transportClient.execute(PercolateAction.INSTANCE, request).actionGet();

Using percolate request builder:

PercolateRequestBuilder builder = new PercolateRequestBuilder(transportClient, PercolateAction.INSTANCE);
// set stuff and then execute:
PercolateResponse response = builder.get();

Using multi percolate request:

MultiPercolateRequest request = new MultiPercolateRequest();
// set stuff and then execute:
MultiPercolateResponse response = transportClient.execute(MultiPercolateAction.INSTANCE, request).get();

Using multi percolate request builder:

MultiPercolateRequestBuilder builder = new MultiPercolateRequestBuilder(transportClient, MultiPercolateAction.INSTANCE);
// set stuff and then execute:
MultiPercolateResponse response = builder.get();