This new snapshot mostly brings a change to TopFieldCollector which can now
early terminate collection when trackTotalHits is `false`.
As a follow-up, we should replace our usage of
`EarlyTerminatingSortingCollector` with this new option.
The main highlight of this new snapshot is that it introduces the opportunity
for queries to opt out of caching. In case a query opts out of caching, not only
will it never be cached, but also no compound query that wraps it will be
cached.
Also include _type and _id for parent/child hits inside inner hits.
In the case of top_hits aggregation the nested search hits are
directly returned and are not grouped by a root or parent document, so
it is important to include the _id and _index attributes in order to know
to what documents these nested search hits belong to.
Closes#27053
The `delimited_payload_filter` is renamed to `delimited_payload`, the old name is
deprecated and should be replaced by `delimited_payload`.
Closes#21978
Today we require users to prepare their indices for split operations.
Yet, we can do this automatically when an index is created which would
make the split feature a much more appealing option since it doesn't have
any 3rd party prerequisites anymore.
This change automatically sets the number of routinng shards such that
an index is guaranteed to be able to split once into twice as many shards.
The number of routing shards is scaled towards the default shard limit per index
such that indices with a smaller amount of shards can be split more often than
larger ones. For instance an index with 1 or 2 shards can be split 10x
(until it approaches 1024 shards) while an index created with 128 shards can only
be split 3x by a factor of 2. Please note this is just a default value and users
can still prepare their indices with `index.number_of_routing_shards` for custom
splitting.
NOTE: this change has an impact on the document distribution since we are changing
the hash space. Documents are still uniformly distributed across all shards but since
we are artificually changing the number of buckets in the consistent hashign space
document might be hashed into different shards compared to previous versions.
This is a 7.0 only change.
This change stops indexing the `_primary_term` field for nested documents
to allow fast retrieval of parent documents. Today we create a docvalues
field for children to ensure we have a dense datastructure on disk. Yet,
since we only use the primary term to tie-break on when we see the same
seqID on indexing having a dense datastructure is less important. We can
use this now to improve the nested docs performance and it's memory footprint.
Relates to #24362
Removing the unnecessary RankEvalTestHelper, making use of the common test infra
in ESTestCase, also hardening a few of the classes by making more fields final.
This change removes the module named aggs-composite and adds the `composite` aggs
as a core aggregation. This allows other plugins to use this new aggregation
and simplifies the integration in the HL rest client.
Today Cross Cluster Search requires at least one node in each remote cluster to be up once the cross cluster search is run. Otherwise the whole search request fails despite some of the data (either local and/or remote) is available. This happens when performing the _search/shards calls to find out which remote shards the query has to be executed on. This scenario is different from shard failures that may happen later on when the query is actually executed, in case e.g. remote shards are missing, which is not going to fail the whole request but rather yield partial results, and the _shards section in the response will indicate that.
This commit introduces a boolean setting per cluster called search.remote.$cluster_alias.skip_if_disconnected, set to false by default, which allows to skip certain clusters if they are down when trying to reach them through a cross cluster search requests. By default all clusters are mandatory.
Scroll requests support such setting too when they are first initiated (first search request with scroll parameter), but subsequent scroll rounds (_search/scroll endpoint) will fail if some of the remote clusters went down meanwhile.
The search API response contains now a new _clusters section, similar to the _shards section, that gets returned whenever one or more clusters were disconnected and got skipped:
"_clusters" : {
"total" : 3,
"successful" : 2,
"skipped" : 1
}
Such section won't be part of the response if no clusters have been skipped.
The per cluster skip_unavailable setting value has also been added to the output of the remote/info API.
This is related to #27422. Right now when we send a write to the netty
transport, we attach a listener to the future. When you submit a write
on the netty event loop and the event loop is shutdown, the onFailure
method is called. Unfortunately, netty then tries to notify the listener
which cannot be done without dispatching to the event loop. In this
case, the dispatch fails and netty logs and error and does not tell us.
This commit checks that netty is still not shutdown after sending a
message. If netty is shutdown, we complete the listener.
Currently we use ActionListener<TcpChannel> for connect, close, and send
message listeners in TcpTransport. However, all of the listeners have to
capture a reference to a channel in the case of the exception api being
called. This commit changes these listeners to be type <Void> as passing
the channel to onResponse is not necessary. Additionally, this change
makes it easier to integrate with low level transports (which use
different implementations of TcpChannel).
This commit is a follow up to the work completed in #27132. Essentially
it transitions two more methods (sendMessage and getLocalAddress) from
Transport to TcpChannel. With this change, there is no longer a need for
TcpTransport to be aware of the specific type of channel a transport
returns. So that class is no longer parameterized by channel type.
* This change adds a module called `aggs-composite` that defines a new aggregation named `composite`.
The `composite` aggregation is a multi-buckets aggregation that creates composite buckets made of multiple sources.
The sources for each bucket can be defined as:
* A `terms` source, values are extracted from a field or a script.
* A `date_histogram` source, values are extracted from a date field and rounded to the provided interval.
This aggregation can be used to retrieve all buckets of a deeply nested aggregation by flattening the nested aggregation in composite buckets.
A composite buckets is composed of one value per source and is built for each document as the combinations of values in the provided sources.
For instance the following aggregation:
````
"test_agg": {
"terms": {
"field": "field1"
},
"aggs": {
"nested_test_agg":
"terms": {
"field": "field2"
}
}
}
````
... which retrieves the top N terms for `field1` and for each top term in `field1` the top N terms for `field2`, can be replaced by a `composite` aggregation in order to retrieve **all** the combinations of `field1`, `field2` in the matching documents:
````
"composite_agg": {
"composite": {
"sources": [
{
"field1": {
"terms": {
"field": "field1"
}
}
},
{
"field2": {
"terms": {
"field": "field2"
}
}
},
}
}
````
The response of the aggregation looks like this:
````
"aggregations": {
"composite_agg": {
"buckets": [
{
"key": {
"field1": "alabama",
"field2": "almanach"
},
"doc_count": 100
},
{
"key": {
"field1": "alabama",
"field2": "calendar"
},
"doc_count": 1
},
{
"key": {
"field1": "arizona",
"field2": "calendar"
},
"doc_count": 1
}
]
}
}
````
By default this aggregation returns 10 buckets sorted in ascending order of the composite key.
Pagination can be achieved by providing `after` values, the values of the composite key to aggregate after.
For instance the following aggregation will aggregate all composite keys that sorts after `arizona, calendar`:
````
"composite_agg": {
"composite": {
"after": {"field1": "alabama", "field2": "calendar"},
"size": 100,
"sources": [
{
"field1": {
"terms": {
"field": "field1"
}
}
},
{
"field2": {
"terms": {
"field": "field2"
}
}
}
}
}
````
This aggregation is optimized for indices that set an index sorting that match the composite source definition.
For instance the aggregation above could run faster on indices that defines an index sorting like this:
````
"settings": {
"index.sort.field": ["field1", "field2"]
}
````
In this case the `composite` aggregation can early terminate on each segment.
This aggregation also accepts multi-valued field but disables early termination for these fields even if index sorting matches the sources definition.
This is mandatory because index sorting picks only one value per document to perform the sort.
Right now our different transport implementations must duplicate
functionality in order to stay compliant with the requirements of
TcpTransport. They must all implement common logic to open channels,
close channels, keep track of channels for eventual shutdown, etc.
Additionally, there is a weird and complicated relationship between
Transport and TransportService. We eventually want to start merging
some of the functionality between these classes.
This commit starts moving towards a world where TransportService retains
all the application logic and channel state. Transport implementations
in this world will only be tasked with returning a channel when one is
requested, calling transport service when a channel is accepted from
a server, and starting / stopping itself.
Specifically this commit changes how channels are opened and closed. All
Transport implementations now return a channel type that must comply with
the new TcpChannel interface. This interface has the methods necessary
for TcpTransport to completely manage the lifecycle of a channel. This
includes setting the channel up, waiting for connection, adding close
listeners, and eventually closing.
* REST: Rename ingest.processor.grok to ingest.processor_grok
* REST: Rename remote.info to cluster.remote_info
* REST: Fixed bad YAML comments
* REST: Force dummy scripts to be strings, not numbers
* REST: Fix bad YAML in search/110_field_collapsing.yml
* REST: Adjust percentile tests to work with Perl number handling
The Json Processor originally only supported parsing field values into Maps even
though the JSON spec specifies that strings, null-values, numbers, booleans, and arrays
are also valid JSON types. This commit enables parsing these values now.
response to #25972.
This is a followup to #26521. This commit expands the alias added for
the elasticsearch client codebase to all codebases. The original full
jar name property is left intact. This only adds an alias without the
version, which should help ease the pain in updating any versions (ES
itself or dependencies).
the query would be marked as verified candidate match. This is wrong as it can only marked as verified candidate match
on indices created on or after 6.1, due to the use of the CoveringQuery.
extract all clauses from a conjunction query.
When clauses from a conjunction are extracted the number of clauses is
also stored in an internal doc values field (minimum_should_match field).
This field is used by the CoveringQuery and allows the percolator to
reduce the number of false positives when selecting candidate matches and
in certain cases be absolutely sure that a conjunction candidate match
will match and then skip MemoryIndex validation. This can greatly improve
performance.
Before this change only a single clause was extracted from a conjunction
query. The percolator tried to extract the clauses that was rarest in order
(based on term length) to attempt less candidate queries to be selected
in the first place. However this still method there is still a very high
chance that candidate query matches are false positives.
This change also removes the influencing query extraction added via #26081
as this is no longer needed because now all conjunction clauses are extracted.
https://www.elastic.co/guide/en/elasticsearch/reference/6.x/percolator.html#_influencing_query_extractionCloses#26307
Sometimes systems like Beats would want to extract the date's timezone and/or locale
from a value in a field of the document. This PR adds support for mustache templating
to extract these values.
Closes#24024.
* Add limits for ngram and shingle settings (#27211)
Create index-level settings:
max_ngram_diff - maximum allowed difference between max_gram and min_gram in
NGramTokenFilter/NGramTokenizer. Default is 1.
max_shingle_diff - maximum allowed difference between max_shingle_size and
min_shingle_size in ShingleTokenFilter. Default is 3.
Throw an IllegalArgumentException when
trying to create NGramTokenFilter, NGramTokenizer, ShingleTokenFilter
where difference between max_size and min_size exceeds the settings value.
Closes#25887
Only tests should use the single argument Environment constructor. To
enforce this the single arg Environment constructor has been replaced with
a test framework factory method.
Production code (beyond initial Bootstrap) should always use the same
Environment object that Node.getEnvironment() returns. This Environment
is also available via dependency injection.
If creating the REST request throws an exception (for example, because
of invalid headers), we leak the request due to failure to release the
buffer (which would otherwise happen after replying on the
channel). This commit addresses this leak by handling the failure case.
Relates #27222
* Enhances exists queries to reduce need for `_field_names`
Before this change we wrote the name all the fields in a document to a `_field_names` field and then implemented exists queries as a term query on this field. The problem with this approach is that it bloats the index and also affects indexing performance.
This change adds a new method `existsQuery()` to `MappedFieldType` which is implemented by each sub-class. For most field types if doc values are available a `DocValuesFieldExistsQuery` is used, falling back to using `_field_names` if doc values are disabled. Note that only fields where no doc values are available are written to `_field_names`.
Closes#26770
* Addresses review comments
* Addresses more review comments
* implements existsQuery explicitly on every mapper
* Reinstates ability to perform term query on `_field_names`
* Added bwc depending on index created version
* Review Comments
* Skips tests that are not supported in 6.1.0
These values will need to be changed after backporting this PR to 6.x
When a search is executing locally over many shards, we can stack
overflow during query phase execution. This happens due to callbacks
that occur after a phase completes for a shard and we move to the same
phase on another shard. If all the shards for the query are local to the
local node then we will never go async and these callbacks will end up
as recursive calls. With sufficiently many shards, this will end up as a
stack overflow. This commit addresses this by truncating the stack by
forking to another thread on the executor for the phase.
Relates #27069
The headers passed to reindex were skipped except for the last one. This
commit fixes the copying of the headers, as well as adds a base test
case for rest client builders to access the headers within the built
rest client.
relates #22976
This commit removes the `ByteBufStreamInput` `readBytesReference` and
`readBytesRef` methods. These methods are zero-copy which means that
they retain a reference to the underlying netty buffer. The problem is
that our `TcpTransport` is not designed to handle zero-copy. The netty
implementation sets the read index past the current message once it has
been deserialized, handled, and mostly likely dispatched to another
thread. This means that netty is free to release this buffer. So it is
unsafe to retain a reference to it without calling `retain`. And we
cannot call `retain` because we are not currently designed to handle
reference counting past the transport level.
This should not currently impact us as we wrap the `ByteBufStreamInput`
in `NamedWriteableAwareStreamInput` in the `TcpTransport`. This stream
essentially delegates to the underling stream. However, in the case of
`readBytesReference` and `readBytesRef` it leaves thw implementations
to the standard `StreamInput` methods. These methods call the read byte
array method which delegates to `ByteBufStreamInput`. The read byte
array method on `ByteBufStreamInput` copies so it is safe. The only
impact of this commit should be removing methods that could be dangerous
if they were eventually called due to some refactoring.
Upgrade to Jackson 2.9.2 and also use a boolean `closed` flag to
indicate that a FastStringReader instance is closed, so that length
is still correctly reported after the reader is closed.
Today all these API calls have a sideeffect of making documents visible
to search requests. While this is sometimes desired it's an unnecessary sideeffect
and now that we have an internal (engine-private) index reader (#26972) we artificially
add a refresh call for bwc. This change removes this sideeffect in 7.0.
Right now we are attempting to set SO_LINGER to 0 on server channels
when we are stopping the tcp transport. This is not a supported socket
option and throws an exception. This also prevents the channels from
being closed.
This commit 1. doesn't set SO_LINGER for server channges, 2. checks
that it is a supported option in nio, and 3. changes the log message
to warn for server channel close exceptions.
While opening a connection to a node, a channel can subsequently
close. If this happens, a future callback whose purpose is to close all
other channels and disconnect from the node will fire. However, this
future will not be ready to close all the channels because the
connection will not be exposed to the future callback yet. Since this
callback is run once, we will never try to disconnect from this node
again and we will be left with a closed channel. This commit adds a
check that all channels are open before exposing the channel and throws
a general connection exception. In this case, the usual connection retry
logic will take over.
Relates #26932
We had a TODO about adding tests around cached boxing. In #24077
I tracked down the uncached boxing tests and saw the TODO. Cached
boxing testing is a fairly small extension to that work.
With this commit we simplify our network layer by only allowing to define a
fixed receive predictor size instead of a minimum and maximum value. This also
means that the following (previously undocumented) settings are removed:
* http.netty.receive_predictor_min
* http.netty.receive_predictor_max
Using an adaptive sizing policy in the receive predictor is a very low-level
optimization. The implications on allocation behavior are extremely hard to grasp
(see our previous work in #23185) and adaptive sizing does not provide a lot of
benefits (see benchmarks in #26165 for more details).
Today we return a `String[]` that requires copying values for every
access. Yet, we already store the setting as a list so we can also directly
return the unmodifiable list directly. This makes list / array access in settings
a much cheaper operation especially if lists are large.
Right now if you run `gradle regen` on Windows you'll get `CRLF` line
endings on all the ANTLR generated files because we run
```
ant.fixcrlf(srcdir: outputPath) {
patternset(includes: 'Painless*.java')
}
```
The docs for fixcrlf say that the default line endings that it
corrects to is based on the OS:
https://ant.apache.org/manual/Tasks/fixcrlf.html
This change locks it to `LF`.
* Add additional low-level logging handler
We have the trace handler which is useful for recording sent messages
but there are times where it would be useful to have more low-level
logging about the events occurring on a channel. This commit adds a
logging handler that can be enabled by setting a certain log level
(org.elasticsearch.transport.netty4.ESLoggingHandler) to trace that
provides trace logging on low-level channel events and includes some
information about the request/response read/write events on the channel
as well.
* Remove imports
* License header
* Remove redundant
* Add test
* More assertions
We should unwrap the cause looking for any suppressed errors or root
causes that are errors when checking if we should maybe die. This commit
causes that to be the case.
Relates #26884
This commit changes the log level on a write and flush failure to warn
as this is not necessarily an Elasticsearch problem but more likely
indicative of an infrastructure problem.
Today we represent each value of a list setting with it's own dedicated key
that ends with the index of the value in the list. Aside of the obvious
weirdness this has several issues especially if lists are massive since it
causes massive runtime penalties when validating settings. Like a list of 100k
words will literally cause a create index call to timeout and in-turn massive
slowdown on all subsequent validations runs.
With this change we use a simple string list to represent the list. This change
also forbids to add a settings that ends with a .0 which was internally used to
detect a list setting. Once this has been rolled out for an entire major
version all the internal .0 handling can be removed since all settings will be
converted.
Relates to #26723
Since `#getAsMap` exposes internal representation we are trying to remove it
step by step. This commit is cleaning up some xcontent writing as well as
usage in tests
This commit fixes a #26855. Right now we set SO_LINGER to 0 if we are
stopping the transport. This can throw a ChannelClosedException if the
raw channel is already closed. We have a number of scenarios where it is
possible this could be called with a channel that is already closed.
This commit fixes the issue be checking that the channel is not closed
before attempting to set the socket option.
This commit reorders a maybe die check and a logging statement for the
following reasons:
- we should die as quickly as possible if the cause is fatal
- we do not want the JVM to be so broken that when we try to log
another exception is thrown (maybe another out of memory exception)
and then the maybe die is never invoked
- maybe die will log the cause anyway if the cause is fatal so we only
need to log if the cause is not fatal
Numeric fields no longer support the index_options parameter. This changes the parameter
to be rejected in numeric field types after it was deprecated in 6.0.
Closes#21475
We were accidentally defaulting it to the scroll size.
Untwists some of the tricks that we play with parsing
so that the size is no longer scrambled.
Closes#26761
This change adds a fromXContent method to Settings that allows to read
the xcontent that is produced by toXContent. It also replaces the entire settings
loader infrastructure and removes the structured map representation. Future PRs will
also tackle the `getAsMap` that exposes the internal represenation of settings for
better encapsulation.
The `fielddata` field and the use of the `_name` field in the short syntax of the range
query have been deprecated in 5.0 and can be removed.
The same goes for the deprecated `score_mode` field in HasParentQueryBuilder,
the deprecated `like_text`, `ids` and `docs` parameter in the `more_like_this` query,
the deprecated query name in the short version of the `regexp` query, and several
deprecated alternative field names in other query builders.
The `type` field has been deprecated in 5.0 and can be removed. It has been
replaced by using the MatchPhraseQueryBuilder or the
MatchPhrasePrefixQueryBuilder. The `slop` field has also been deprecated and can
be removed, the phrase and phrase prefix query builders still provide this
parameter.
Adds several small whitelist data structures and a new Whitelist class to separate the idea of loading a whitelist from the actual Painless Definition class. This is the first step of many in allowing users to define custom whitelists per context. Also supports the idea of loading multiple whitelists from different sources for a single context.
Today we can't validate the array length in `InputStreamStreamInput` since
we can't rely on `InputStream.available` yet in some situations we know
the size of the stream and can apply additional validation.
Removing several occurrences of this typo in the docs and javadocs, seems to be
a common mistake. Corrections turn up once in a while in PRs, better to correct
some of this in one sweep.
* Fix percolator highlight sub fetch phase to not highlight query twice
The PercolatorHighlightSubFetchPhase does not override hitExecute and since it extends HighlightPhase the search hits
are highlighted twice (by the highlight phase and then by the percolator). This does not alter the results, the second highlighting
just overrides the first one but this slow down the request because it duplicates the work.
Today we have all non-plugin mappers in core. I'd like to start moving those
that neither map to json datatypes nor are very frequently used like `date` or
`ip` to a module.
This commit creates a new module called `mappers-extra` and moves the
`scaled_float` and `token_count` mappers to it. I'd like to eventually move
`range` fields there but it's more complicated due to their intimate
relationship with range queries.
Relates #10368
RangeQueryBuilder needs to perform too many `instanceof` checks in order to
check for `date` or `range` fields in order to know what it should do with the
shape relation, time zone and date format.
This commit adds those 3 parameters to the `rangeQuery` factory method so that
those instanceof checks are not necessary anymore.
The percolator will add a `_percolator_document_slot` field to all percolator
hits to indicate with what document it has matched. This number matches with
the order in which the documents have been specified in the percolate query.
Also improved the support for multiple percolate queries in a search request.
Security manager policy files contains grants for specific codebases,
where a codebase is a jar file. We use a system property containing the
name of the jar file to resolve the jar file location when parsing the
policy file. However, this means the version of the jars must be
modified when versions of dependencies change. This is particularly
messy for elasticsearch, where we now have a dependency on the rest
client, and need to support both a snapshot version for testing and non
snapshot for release.
This commit adds an alias for the elasticsearch rest client without a
version to be used in policy files. That allows the policy files to not care whether
the rest client is a snapshot or release.
* If in a range query upper is smaller than lower then ignore the range query
* If two empty range extractions are compared don't fail with NoSuchElementException
The `index.percolator.map_unmapped_fields_as_text` is a more better name, because unmapped fields are mapped to a text field with default settings
and string is no longer a field type (it is either keyword or text).
The current script service has a script compilation limit for a one
minute window. This is set to a small default value of 15. Instead of
increasing that default value, this commit introduces a new setting
that allows to configure a rate per time unit, so that the script service can deal with bursts better.
The new setting is named `script.max_compilations_rate`,
requires a nonnegative number and a positive time value.
The default is `75/5m`, which is equivalent to the existing 15 per minute.
* Moves deferring code into its own subclass
This change moves the code that deals with deferring collection to a subclass of BucketAggregator called DeferringBucketAggregator. This means that the code in AggregatorBase is simplified and also means that the code for deferring colleciton is in one place and easier to maintain.
* Makes SIngleBucketAggregator an interface
This is so aggregators that extend BucketsAggregator directly and those that extend DeferringBucketAggregator can be a single bucket aggregator
* review comments
* More review comments
* Remove the _all metadata field
This change removes the `_all` metadata field. This field is deprecated in 6
and cannot be activated for indices created in 6 so it can be safely removed in
the next major version (e.g. 7).
At current, we do not feel there is enough of a reason to shade the low
level rest client. It caused problems with commons logging and IDE's
during the brief time it was used. We did not know exactly how many
users will need this, and decided that leaving shading out until we
gather more information is best. Users can still shade the jar
themselves. For information and feeback, see issue #26366.
Closes#26328
This reverts commit 3a20922046.
This reverts commit 2c271f0f22.
This reverts commit 9d10dbea39.
This reverts commit e816ef89a2.
There is a group of five settings relating to raw tcp configurations
(no_delay, buffer sizes, etc) that we have for the http transport. These
currently live in the netty module. As they are unrelated to netty
specifically, this commit moves these settings to the
`HttpTransportSettings` class in core.
When slices is set as auto, there's an additional network call
needed for the reindex tasks to know how to rethrottle. Sometimes
the rethrottle action happens before the reindex task is fully
initialized, so in the test we wait for the task to be ready.
This commit also adds some safeguards to ensure that
cancel and rethrottle operations are handled correctly
Closes#26192
Links to inner classes were using `$` in urls instead of `.`, causing
them to 404.
Also fixes the doc generation code to generate docs into the correct
directory. We moved the docs but never updated the generation code.
Right now it is possible for the `HttpPipeliningHandler` to queue
pipelined responses. On channel close, we do not clear and release these
responses. This commit releases the responses and completes the promise.
Due to the weird way of structuring the serialization code in AcknowledgedRequest, many request types forgot to properly serialize the request timeout, for example "index deletion", "index rollover", "index shrink", "putting pipeline", and other requests. This means that if those requests were not directly sent to the master node, the acknowledgement timeout information would be lost (and the default used instead).
Some requests also don't properly expose the timeout mechanism in the REST layer, such as put / delete stored script. This commit fixes all that.
This test was too lenient with its randomization of targetFieldName and
resulting in a conflict with the original existing fields. This commit
fixes that.
Closes#26177.
The following token filters were moved: arabic_stem, brazilian_stem, czech_stem, dutch_stem, french_stem, german_stem and russian_stem.
Relates to #23658
In reindex APIs, when using the `slices` parameter to choose the number of slices, adds the option to specify `slices` as "auto" which will choose a reasonable number of slices. It uses the number of shards in the source index, up to a ceiling. If there is more than one source index, it uses the smallest number of shards among them.
This gives users an easy way to use slicing in these APIs without having to make decisions about how to configure it, as it provides a good-enough configuration for them out of the box. This may become the default behavior for these APIs in the future.
The percolator field mapper doesn't need to extract all terms and ranges from a bool query with must or filter clauses.
In order to help to default extraction behavior, boost fields can be configured, so that fields that are known for not being
selective enough can be ignored in favor for other fields or clauses with specific fields can forcefully take precedence over other clauses.
This can help selecting clauses for fields that don't match with a lot of percolator queries over other clauses and thus improving performance of the percolate query.
For example a status like field is something that should configured as an ignore field.
Queries on this field tend to match with more documents and so if clauses for this fields
get selected as best clause then that isn't very helpful for the candidate query that the
percolate query generates to filter out percolator queries that are likely not going to match.
With this commit we remove the following three previously unused
(and undocumented) Netty 4 related settings:
* transport.netty.max_cumulation_buffer_capacity,
* transport.netty.max_composite_buffer_components and
* http.netty.max_cumulation_buffer_capacity
from Elasticsearch.
We introduced a hack in #25885 to respect the cluster alias if available on the `_index` field. This is important if aggregations or other field data related operations are executed. Yet, we added a small hack that duplicated an implementation detail from the `_index` field data builder to make this work. This change adds a necessary but simple API change that allows us to remove the hack and only have a single implementation.
The goal of this similarity is to help users who would like to keep the
functionality of the `tf-idf` similarity that we want to remove, or to allow
for specific usec-cases (disabling idf, disabling tf, disabling length norm,
etc.) to not have to build a custom plugin and familiarize with the low-level
Lucene API.