- Replace immediate task creations by using task avoidance api
- One step closer to #56610
- Still many tasks are created during configuration phase. Tackled in separate steps
Backport of #59293 to 7.x branch.
* Create new data-stream xpack module.
* Move TimestampFieldMapper to the new module,
this results in storing a composable index template
with data stream definition only to work with default
distribution. This way data streams can only be used
with default distribution, since a data stream can
currently only be created if a matching composable index
template exists with a data stream definition.
* Renamed `_timestamp` meta field mapper
to `_data_stream_timestamp` meta field mapper.
* Add logic to put composable index template api
to fail if `_data_stream_timestamp` meta field mapper
isn't registered. So that a more understandable
error is returned when attempting to store a template
with data stream definition via the oss distribution.
In a follow up the data stream transport and
rest actions can be moved to the xpack data-stream module.
Backport of #59076 to 7.x branch.
The commit makes the following changes:
* The timestamp field of a data stream definition in a composable
index template can only be set to '@timestamp'.
* Removed custom data stream timestamp field validation and reuse the validation from `TimestampFieldMapper` and
instead only check that the _timestamp field mapping has been defined on a backing index of a data stream.
* Moved code that injects _timestamp meta field mapping from `MetadataCreateIndexService#applyCreateIndexRequestWithV2Template58956(...)` method
to `MetadataIndexTemplateService#collectMappings(...)` method.
* Fixed a bug (#58956) that cases timestamp field validation to be performed
for each template and instead of the final mappings that is created.
* only apply _timestamp meta field if index is created as part of a data stream or data stream rollover,
this fixes a docs test, where a regular index creation matches (logs-*) with a template with a data stream definition.
Relates to #58642
Relates to #53100Closes#58956Closes#58583
This commit creates a new Gradle plugin to provide a separate task name
and source set for running YAML based REST tests. The only project
converted to use the new plugin in this PR is distribution/archives/integ-test-zip.
For which the testing has been moved to :rest-api-spec since it makes the most
sense and it avoids a small but awkward change to the distribution plugin.
The remaining cases in modules, plugins, and x-pack will be handled in followups.
This plugin is distinctly different from the plugin introduced in #55896 since
the YAML REST tests are intended to be black box tests over HTTP. As such they
should not (by default) have access to the classpath for that which they are testing.
The YAML based REST tests will be moved to separate source sets (yamlRestTest).
The which source is the target for the test resources is dependent on if this
new plugin is applied. If it is not applied, it will default to the test source
set.
Further, this introduces a breaking change for plugin developers that
use the YAML testing framework. They will now need to either use the new source set
and matching task, or configure the rest resources to use the old "test" source set that
matches the old integTest task. (The former should be preferred).
As part of this change (which is also breaking for plugin developers) the
rest resources plugin has been removed from the build plugin and now requires
either explicit application or application via the new YAML REST test plugin.
Plugin developers should be able to fix the breaking changes to the YAML tests
by adding apply plugin: 'elasticsearch.yaml-rest-test' and moving the YAML tests
under a yamlRestTest folder (instead of test)
Today we have individual settings for configuring node roles such as
node.data and node.master. Additionally, roles are pluggable and we have
used this to introduce roles such as node.ml and node.voting_only. As
the number of roles is growing, managing these becomes harder for the
user. For example, to create a master-only node, today a user has to
configure:
- node.data: false
- node.ingest: false
- node.remote_cluster_client: false
- node.ml: false
at a minimum if they are relying on defaults, but also add:
- node.master: true
- node.transform: false
- node.voting_only: false
If they want to be explicit. This is also challenging in cases where a
user wants to have configure a coordinating-only node which requires
disabling all roles, a list which we are adding to, requiring the user
to keep checking whether a node has acquired any of these roles.
This commit addresses this by adding a list setting node.roles for which
a user has explicit control over the list of roles that a node has. If
the setting is configured, the node has exactly the roles in the list,
and not any additional roles. This means to configure a master-only
node, the setting is merely 'node.roles: [master]', and to configure a
coordinating-only node, the setting is merely: 'node.roles: []'.
With this change we deprecate the existing 'node.*' settings such as
'node.data'.
This change allows to use an `index_filter` in the
field capabilities API. Indices are filtered from
the response if the provided query rewrites to `match_none`
on every shard:
````
GET metrics-*
{
"index_filter": {
"bool": {
"must": [
"range": {
"@timestamp": {
"gt": "2019"
}
}
}
}
}
````
The filtering is done on a best-effort basis, it uses the can match phase
to rewrite queries to `match_none` instead of fully executing the request.
The first shard that can match the filter is used to create the field
capabilities response for the entire index.
Closes#56195
* Remove usage of deprecated testCompile configuration
* Replace testCompile usage by testImplementation
* Make testImplementation non transitive by default (as we did for testCompile)
* Update CONTRIBUTING about using testImplementation for test dependencies
* Fail on testCompile configuration usage
* Add ValuesSource Registry and associated logic (#54281)
* Remove ValuesSourceType argument to ValuesSourceAggregationBuilder (#48638)
* ValuesSourceRegistry Prototype (#48758)
* Remove generics from ValuesSource related classes (#49606)
* fix percentile aggregation tests (#50712)
* Basic thread safety for ValuesSourceRegistry (#50340)
* Remove target value type from ValuesSourceAggregationBuilder (#49943)
* Cleanup default values source type (#50992)
* CoreValuesSourceType no longer implements Writable (#51276)
* Remove genereics & hard coded ValuesSource references from Matrix Stats (#51131)
* Put values source types on fields (#51503)
* Remove VST Any (#51539)
* Rewire terms agg to use new VS registry (#51182)
Also adds some basic AggTestCases for untested code
paths (and boilerplate for future tests once the IT are
converted over)
* Wire Cardinality aggregation to work with the ValuesSourceRegistry (#51337)
* Wire Percentiles aggregator into new VS framework (#51639)
This required a bit of a refactor to percentiles itself. Before,
the Builder would switch on the chosen algo to generate an
algo-specific factory. This doesn't work (or at least, would be
difficult) in the new VS framework.
This refactor consolidates both factories together and introduces
a PercentilesConfig object to act as a standardized way to pass
algo-specific parameters through the factory. This object
is then used when deciding which kind of aggregator to create
Note: CoreValuesSourceType.HISTOGRAM still lives in core, and will
be moved in a subsequent PR.
* Remove generics and target value type from MultiVSAB (#51647)
* fix checkstyle after merge (#52008)
* Plumb ValuesSourceRegistry through to QuerySearchContext (#51710)
* Convert RareTerms to new VS registry (#52166)
* Wire up Value Count (#52225)
* Wire up Max & Min aggregations (#52219)
* ValuesSource refactoring: Wire up Sum aggregation (#52571)
* ValuesSource refactoring: Wire up SigTerms aggregation (#52590)
* Soft immutability for VSConfig (#52729)
* Unmute testSupportedFieldTypes, fix Percentiles/Ranks/Terms tests (#52734)
Also fixes Percentiles which was incorrectly specified to only accept
numeric, but in fact also accepts Boolean and Date (because those are
numeric on master - thanks `testSupportedFieldTypes` for catching it!)
* VS refactoring: Wire up stats aggregation (#52891)
* ValuesSource refactoring: Wire up string_stats aggregation (#52875)
* VS refactoring: Wire up median (MAD) aggregation (#52945)
* fix valuesourcetype issue with constant_keyword field (#53041)x-pack/plugin/rollup/src/main/java/org/elasticsearch/xpack/rollup/job/RollupIndexer.java
this commit implements `getValuesSourceType` for
the ConstantKeyword field type.
master was merged into feature/extensible-values-source
introducing a new field type that was not implementing
`getValuesSourceType`.
* ValuesSource refactoring: Wire up Avg aggregation (#52752)
* Wire PercentileRanks aggregator into new VS framework (#51693)
* Add a VSConfig resolver for aggregations not using the registry (#53038)
* Vs refactor wire up ranges and date ranges (#52918)
* Wire up geo_bounds aggregation to ValuesSourceRegistry (#53034)
This commit updates the geo_bounds aggregation to depend
on registering itself in the ValuesSourceRegistry
relates #42949.
* VS refactoring: convert Boxplot to new registry (#53132)
* Wire-up geotile_grid and geohash_grid to ValuesSourceRegistry (#53037)
This commit updates the geo*_grid aggregations to depend
on registering itself in the ValuesSourceRegistry
relates to the values-source refactoring meta issue #42949.
* Wire-up geo_centroid agg to ValuesSourceRegistry (#53040)
This commit updates the geo_centroid aggregation to depend
on registering itself in the ValuesSourceRegistry.
relates to the values-source refactoring meta issue #42949.
* Fix type tests for Missing aggregation (#53501)
* ValuesSource Refactor: move histo VSType into XPack module (#53298)
- Introduces a new API (`getBareAggregatorRegistrar()`) which allows plugins to register aggregations against existing agg definitions defined in Core.
- This moves the histogram VSType over to XPack where it belongs. `getHistogramValues()` still remains as a Core concept
- Moves the histo-specific bits over to xpack (e.g. the actual aggregator logic). This requires extra boilerplate since we need to create a new "Analytics" Percentile/Rank aggregators to deal with the histo field. Doubly-so since percentiles/ranks are extra boiler-plate'y... should be much lighter for other aggs
* Wire up DateHistogram to the ValuesSourceRegistry (#53484)
* Vs refactor parser cleanup (#53198)
Co-authored-by: Zachary Tong <polyfractal@elastic.co>
Co-authored-by: Zachary Tong <zach@elastic.co>
Co-authored-by: Christos Soulios <1561376+csoulios@users.noreply.github.com>
Co-authored-by: Tal Levy <JubBoy333@gmail.com>
* First batch of easy fixes
* Remove List.of from ValuesSourceRegistry
Note that we intend to have a follow up PR dealing with the mutability
of the registry, so I didn't even try to address that here.
* More compiler fixes
* More compiler fixes
* More compiler fixes
* Precommit is happy and so am I
* Add new Core VSTs to tests
* Disabled supported type test on SigTerms until we can backport it's fix
* fix checkstyle
* Fix test failure from semantic merge issue
* Fix some metaData->metadata replacements that got lost
* Fix list of supported types for MinAggregator
* Fix list of supported types for Avg
* remove unused import
Co-authored-by: Zachary Tong <polyfractal@elastic.co>
Co-authored-by: Zachary Tong <zach@elastic.co>
Co-authored-by: Christos Soulios <1561376+csoulios@users.noreply.github.com>
Co-authored-by: Tal Levy <JubBoy333@gmail.com>
`scripted_metric` did not work with cross cluster search because it
assumed that you'd never perform a partial reduction, serialize the
results, and then perform a final reduction. That
serialized-after-partial-reduction step was broken.
This is also required to support #54758.
This drop the "top level" pipeline aggregators from the aggregation
result tree which should save a little memory and a few serialization
bytes. Perhaps more imporantly, this provides a mechanism by which we
can remove *all* pipelines from the aggregation result tree. This will
save quite a bit of space when pipelines are deep in the tree.
Sadly, doing this isn't simple because of backwards compatibility. Nodes
before 7.7.0 *need* those pipelines. We provide them by setting passing
a `Supplier<PipelineTree>` into the root of the aggregation tree that we
only call if we need to serialize to a version before 7.7.0.
This solution works for cross cluster search because we always reduce
the aggregations in each remote cluster and then forward them back to
the coordinating node. Its quite possible that the coordinating node
needs the pipeline (say it is version 7.1.0) and the gateway node in the
remote cluster doesn't (version 7.7.0). In that case the data nodes
won't send the pipeline aggregations back to the gateway node.
Critically, the gateway node *will* send the pipeline aggregations back
to the coordinating node. This is all managed with that
`Supplier<PipelineTree>`, but *how* it is managed is a bit tricky.
Currently the remote info api has added a number of possible fields
(proxy, num_socket_connections, etc) that are available in proxy mode.
These fields are not aligned with what the settings are named. This
commit modifies this API to align with the settings.
This commit changes the pre_filter_shard_size default from 128 to unspecified.
This allows to apply heuristics based on the request and the target indices when deciding
whether the can match phase should run or not. When unspecified, this pr runs the can match phase
automatically if one of these conditions is met:
* The request targets more than 128 shards.
* The request contains read-only indices.
* The primary sort of the query targets an indexed field.
Users can opt-out from this behavior by setting the `pre_filter_shard_size` to a static value.
Closes#39835
* Update remote cluster stats to support simple mode (#49961)
Remote cluster stats API currently only returns useful information if
the strategy in use is the SNIFF mode. This PR modifies the API to
provide relevant information if the user is in the SIMPLE mode. This
information is the configured addresses, max socket connections, and
open socket connections.
* Send hostname in SNI header in simple remote mode (#50247)
Currently an intermediate proxy must route conncctions to the
appropriate remote cluster when using simple mode. This commit offers
a additional mechanism for the proxy to route the connections by
including the hostname in the TLS SNI header.
* Rename the remote connection mode simple to proxy (#50291)
This commit renames the simple connection mode to the proxy connection
mode for remote cluster connections. In order to do this, the mode specific
settings which we namespaced by their mode (ex: sniff.seed and
proxy.addresses) have been reverted.
* Modify proxy mode to support a single address (#50391)
Currently, the remote proxy connection mode uses a list setting for the
proxy address. This commit modifies this so that the setting is
proxy_address and only supports a single remote proxy address.
This change adds a dynamic cluster setting named `indices.id_field_data.enabled`.
When set to `false` any attempt to load the fielddata for the `_id` field will fail
with an exception. The default value in this change is set to `false` in order to prevent
fielddata usage on this field for future versions but it will be set to `true` when backporting
to 7x. When the setting is set to true (manually or by default in 7x) the loading will also issue
a deprecation warning since we want to disallow fielddata entirely when https://github.com/elastic/elasticsearch/issues/26472
is implemented.
Closes#43599
This commit back ports three commits related to enabling the simple
connection strategy.
Allow simple connection strategy to be configured (#49066)
Currently the simple connection strategy only exists in the code. It
cannot be configured. This commit moves in the direction of allowing it
to be configured. It introduces settings for the addresses and socket
count. Additionally it introduces new settings for the sniff strategy
so that the more generic number of connections and seed node settings
can be deprecated.
The simple settings are not yet registered as the registration is
dependent on follow-up work to validate the settings.
Ensure at least 1 seed configured in remote test (#49389)
This fixes#49384. Currently when we select a random subset of seed
nodes from a list, it is possible for 0 seeds to be selected. This test
depends on at least 1 seed being selected.
Add the simple strategy to cluster settings (#49414)
This is related to #49067. This commit adds the simple connection
strategy settings and strategy mode setting to the cluster settings
registry. With these changes, the simple connection mode can be used.
Additionally, it adds validation to ensure that settings cannot be
misconfigured.
Make queries on the “_index” field fast-fail if the target shard is an index that doesn’t match the query expression. Part of the “canMatch” phase optimisations.
Closes#48473
Backport of #48849. Update `.editorconfig` to make the Java settings the
default for all files, and then apply a 2-space indent to all `*.gradle`
files. Then reformat all the files.
Previously, queries on the _index field were not able to specify index aliases.
This was a regression in functionality compared to the 'indices' query that was
deprecated and removed in 6.0.
Now queries on _index can specify an alias, which is resolved to the concrete
index names when we check whether an index matches. To match a remote shard
target, the pattern needs to be of the form 'cluster:index' to match the
fully-qualified index name. Index aliases can be specified in the following query
types: term, terms, prefix, and wildcard.
* Restrict which tasks can use testclusters
This PR fixes a problem between the interaction of test-clusters and
build cache.
Before this any task could have used a cluster without tracking it as
input.
With this change a new interface is introduced to track the tasks that
can use clusters and we do consider the cluster as input for all of
them.
* Testclusters: Convert additional projects
Found some more that were not using testclusters from elasticsearch-ci/1
* Allow IOException too
* Make the client more resilient
The date_histogram accepts an interval which can be either a calendar
interval (DST-aware, leap seconds, arbitrary length of months, etc) or
fixed interval (strict multiples of SI units). Unfortunately this is inferred
by first trying to parse as a calendar interval, then falling back to fixed
if that fails.
This leads to confusing arrangement where `1d` == calendar, but
`2d` == fixed. And if you want a day of fixed time, you have to
specify `24h` (e.g. the next smallest unit). This arrangement is very
error-prone for users.
This PR adds `calendar_interval` and `fixed_interval` parameters to any
code that uses intervals (date_histogram, rollup, composite, datafeed, etc).
Calendar only accepts calendar intervals, fixed accepts any combination of
units (meaning `1d` can be used to specify `24h` in fixed time), and both
are mutually exclusive.
The old interval behavior is deprecated and will throw a deprecation warning.
It is also mutually exclusive with the two new parameters. In the future the
old dual-purpose interval will be removed.
The change applies to both REST and java clients.
* Replace usages RandomizedTestingTask with built-in Gradle Test (#40978)
This commit replaces the existing RandomizedTestingTask and supporting code with Gradle's built-in JUnit support via the Test task type. Additionally, the previous workaround to disable all tasks named "test" and create new unit testing tasks named "unitTest" has been removed such that the "test" task now runs unit tests as per the normal Gradle Java plugin conventions.
(cherry picked from commit 323f312bbc829a63056a79ebe45adced5099f6e6)
* Fix forking JVM runner
* Don't bump shadow plugin version
We recently introduced the option to minimize network roundtrips when
executing cross-cluster search requests. All the changes made around
that are separately unit tested, and there are some yaml tests that
exercise the new code-path which involves multiple coordination steps.
This commit adds new integration tests that compare the output given by
CCS when running the same queries using the two different execution
modes available.
Relates to #32125
This PR removes the temporary change we made to the yml test harness in #37285
to automatically set `include_type_name` to `true` in index creation requests
if it's not already specified. This is possible now that the vast majority of
index creation requests were updated to be typeless in #37611. A few additional
tests also needed updating here.
Additionally, this PR updates the test harness to set `include_type_name` to
`false` in index creation requests when communicating with 6.x nodes. This
mirrors the logic added in #37611 to allow for typeless document write requests
in test set-up code. With this update in place, we can remove many references
to `include_type_name: false` from the yml tests.
With #37000 we made sure that fnial reduction is automatically disabled
whenever a localClusterAlias is provided with a SearchRequest.
While working on #37838, we found a scenario where we do need to set a
localClusterAlias yet we would like to perform a final reduction in the
remote cluster: when searching on a single remote cluster.
Relates to #32125
This commit adds support for a separate finalReduce flag to
SearchRequest and makes use of it in TransportSearchAction in case we
are searching against a single remote cluster.
This also makes sure that num_reduce_phases is correct when searching
against a single remote cluster: it makes little sense to return
`num_reduce_phases` set to `2`, which looks especially weird in case
the search was performed against a single remote shard. We should
perform one reduction phase only in this case and `num_reduce_phases`
should reflect that.
* line length
With #37566 we have introduced the ability to merge multiple search responses into one. That makes it possible to expose a new way of executing cross-cluster search requests, that makes CCS much faster whenever there is network latency between the CCS coordinating node and the remote clusters. The coordinating node can now send a single search request to each remote cluster, which gets reduced by each one of them. from + size results are requested to each cluster, and the reduce phase in each cluster is non final (meaning that buckets are not pruned and pipeline aggs are not executed). The CCS coordinating node performs an additional, final reduction, which produces one search response out of the multiple responses received from the different clusters.
This new execution path will be activated by default for any CCS request unless a scroll is provided or inner hits are requested as part of field collapsing. The search API accepts now a new parameter called ccs_minimize_roundtrips that allows to opt-out of the default behaviour.
Relates to #32125
Users may require the sequence number and primary terms to perform optimistic concurrency control operations. Currently, you can get the sequence number via the `docvalues_fields` API but the primary term is not accessible because it is maintained by the `SeqNoFieldMapper` and the infrastructure can't find it.
This commit adds a dedicated sub fetch phase to return both numbers that is connected to a new `seq_no_primary_term` parameter.
This commit changes the format of the `hits.total` in the search response to be an object with
a `value` and a `relation`. The `value` indicates the number of hits that match the query and the
`relation` indicates whether the number is accurate (in which case the relation is equals to `eq`)
or a lower bound of the total (in which case it is equals to `gte`).
This change also adds a parameter called `rest_total_hits_as_int` that can be used in the
search APIs to opt out from this change (retrieve the total hits as a number in the rest response).
Note that currently all search responses are accurate (`track_total_hits: true`) or they don't contain
`hits.total` (`track_total_hits: true`). We'll add a way to get a lower bound of the total hits in a
follow up (to allow numbers to be passed to `track_total_hits`).
Relates #33028
With features like CCR building on the CCS infrastructure, the settings
prefix search.remote makes less sense as the namespace for these remote
cluster settings than does a more general namespace like
cluster.remote. This commit replaces these settings with cluster.remote
with a fallback to the deprecated settings search.remote.
In case an error is returned when calling search_shards on a remote
cluster, which will lead to throwing an exception in the coordinating
node, we should make sure that the status code returned by the
coordinating node is the same as the one returned by the remote
cluster. Up until now a 500 - Internal Server Error was always
returned. This commit changes this behaviour so that for instance if an
index is not found, which causes an 404, a 404 is also returned by the
coordinating node to the client.
Closes#27461
This commit changes the default out-of-the-box configuration for the
number of shards from five to one. We think this will help address a
common problem of oversharding. For users with time-based indices that
need a different default, this can be managed with index templates. For
users with non-time-based indices that find they need to re-shard with
the split API in place they no longer need to resort only to
reindexing.
Since this has the impact of changing the default number of shards used
in REST tests, we want to ensure that we still have coverage for issues
that could arise from multiple shards. As such, we randomize (rarely)
the default number of shards in REST tests to two. This is managed via a
global index template. However, some tests check the templates that are
in the cluster state during the test. Since this template is randomly
there, we need a way for tests to skip adding the template used to set
the number of shards to two. For this we add the default_shards feature
skip. To avoid having to write our docs in a complicated way because
sometimes they might be behind one shard, and sometimes they might be
behind two shards we apply the default_shards feature skip to all docs
tests. That is, these tests will always run with the default number of
shards (one).
Many tests are added with a version check so that they do not run against a
version that doesn't have the feature yet. Master is 7.0, so all tests that
do not run against 6.0+ can be removed and the version check can be removed
on all tests that always run on 6.0+.
Applying the rest test gradle plugin already uses the zip distribution
by default, so specifying it explicitly is not necessary. These are
leftovers from before zip was the default for rest tests.
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.
* 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 single shard optimization that we have in our search api changes the type of response returned by the query transport action name based on the shard search request. if the request goes to one shard, we will do query and fetch at the same time, hence the response will be different. The proxying layer used in cross cluster search was not aware of this distinction, which causes serialization issues every time a cross cluster search request goes to a single shard and goes through a gateway node which has to forward the shard request to a data node. The coordinating node would then expect a QueryFetchSearchResult while the gateway would return a QuerySearchResult.
Closes#26833
Today when we aggregate on the `_index` field the cross cluster search
alias is not taken into account. Neither is it respected when we search
on the field. This change adds support for cluster alias when the cluster
alias is present on the `_index` field.
Closes#25606
Today if we search across a large amount of shards we hit every shard. Yet, it's quite
common to search across an index pattern for time based indices but filtering will exclude
all results outside a certain time range ie. `now-3d`. While the search can potentially hit
hundreds of shards the majority of the shards might yield 0 results since there is not document
that is within this date range. Kibana for instance does this regularly but used `_field_stats`
to optimize the indexes they need to query. Now with the deprecation of `_field_stats` and it's upcoming removal a single dashboard in kibana can potentially turn into searches hitting hundreds or thousands of shards and that can easily cause search rejections even though the most of the requests are very likely super cheap and only need a query rewriting to early terminate with 0 results.
This change adds a pre-filter phase for searches that can, if the number of shards are higher than a the `pre_filter_shard_size` threshold (defaults to 128 shards), fan out to the shards
and check if the query can potentially match any documents at all. While false positives are possible, a negative response means that no matches are possible. These requests are not subject to rejection and can greatly reduce the number of shards a request needs to hit. The approach here is preferable to the kibana approach with field stats since it correctly handles aliases and uses the correct threadpools to execute these requests. Further it's completely transparent to the user and improves scalability of elasticsearch in general on large clusters.
We lost the cluster alias due to some special caseing in inner hits
and due to the fact that we didn't pass on the alias to the shard request.
This change ensures that we have the cluster alias present on the shard to
ensure all SearchShardTarget reads preserve the alias.
Relates to #25606
This commit changes how we determine if there were any remote indices that a search should have
been executed against. Previously, we used the list of remote shard iterators but if the remote
index pattern resolved to no indices there would be no remote shard iterators even though the
request specified remote indices. The map of remote cluster names to the original indices is used
instead so that we can determine if there were remote indices even when there are no remote shard
iterators.
Closes#25426
Rene Groeschke
Martijn van Groningen
Jake Landis
Jason Tedor
Jim Ferenczi
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Julie Tibshirani
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