OpenSearch/docs/reference/search/search-shards.asciidoc
Luca Cavanna db5a72774b Add indices and filter information to search shards api output (#21738)
Add indices and filter information to search shards api output

The search shards api returns info about which shards are going to be hit by executing a search with provided parameters: indices, routing, preference. Indices can also be aliases, which can also hold filters. The output includes an array of shards and a summary of all the nodes the shards are allocated on. This commit adds a new indices section to the search shards output that includes one entry per index, where each index can be associated with an optional filter in case the index was hit through a filtered alias.

This is relevant since we have moved parsing of alias filters to the coordinating node.

Relates to #20916
2016-11-22 23:00:25 +01:00

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[[search-shards]]
== Search Shards API
The search shards api returns the indices and shards that a search request would
be executed against. This can give useful feedback for working out issues or
planning optimizations with routing and shard preferences. When filtered aliases
are used, the filter is returned as part of the `indices` section.
The `index` may be a single value, or comma-separated.
[float]
=== Usage
Full example:
[source,js]
--------------------------------------------------
GET /twitter/_search_shards
--------------------------------------------------
// CONSOLE
// TEST[s/^/PUT twitter\n/]
This will yield the following result:
[source,js]
--------------------------------------------------
{
"nodes": ...,
"indices" : {
"twitter": { }
},
"shards": [
[
{
"index": "twitter",
"node": "JklnKbD7Tyqi9TP3_Q_tBg",
"primary": true,
"shard": 0,
"state": "STARTED",
"allocation_id": {"id":"0TvkCyF7TAmM1wHP4a42-A"},
"relocating_node": null
}
],
[
{
"index": "twitter",
"node": "JklnKbD7Tyqi9TP3_Q_tBg",
"primary": true,
"shard": 1,
"state": "STARTED",
"allocation_id": {"id":"fMju3hd1QHWmWrIgFnI4Ww"},
"relocating_node": null
}
],
[
{
"index": "twitter",
"node": "JklnKbD7Tyqi9TP3_Q_tBg",
"primary": true,
"shard": 2,
"state": "STARTED",
"allocation_id": {"id":"Nwl0wbMBTHCWjEEbGYGapg"},
"relocating_node": null
}
],
[
{
"index": "twitter",
"node": "JklnKbD7Tyqi9TP3_Q_tBg",
"primary": true,
"shard": 3,
"state": "STARTED",
"allocation_id": {"id":"bU_KLGJISbW0RejwnwDPKw"},
"relocating_node": null
}
],
[
{
"index": "twitter",
"node": "JklnKbD7Tyqi9TP3_Q_tBg",
"primary": true,
"shard": 4,
"state": "STARTED",
"allocation_id": {"id":"DMs7_giNSwmdqVukF7UydA"},
"relocating_node": null
}
]
]
}
--------------------------------------------------
// TESTRESPONSE[s/"nodes": ...,/"nodes": $body.nodes,/]
// TESTRESPONSE[s/JklnKbD7Tyqi9TP3_Q_tBg/$body.shards.0.0.node/]
// TESTRESPONSE[s/0TvkCyF7TAmM1wHP4a42-A/$body.shards.0.0.allocation_id.id/]
// TESTRESPONSE[s/fMju3hd1QHWmWrIgFnI4Ww/$body.shards.1.0.allocation_id.id/]
// TESTRESPONSE[s/Nwl0wbMBTHCWjEEbGYGapg/$body.shards.2.0.allocation_id.id/]
// TESTRESPONSE[s/bU_KLGJISbW0RejwnwDPKw/$body.shards.3.0.allocation_id.id/]
// TESTRESPONSE[s/DMs7_giNSwmdqVukF7UydA/$body.shards.4.0.allocation_id.id/]
And specifying the same request, this time with a routing value:
[source,js]
--------------------------------------------------
GET /twitter/_search_shards?routing=foo,baz
--------------------------------------------------
// CONSOLE
// TEST[s/^/PUT twitter\n/]
This will yield the following result:
[source,js]
--------------------------------------------------
{
"nodes": ...,
"indices" : {
"twitter": { }
},
"shards": [
[
{
"index": "twitter",
"node": "JklnKbD7Tyqi9TP3_Q_tBg",
"primary": true,
"shard": 0,
"state": "STARTED",
"allocation_id": {"id":"0TvkCyF7TAmM1wHP4a42-A"},
"relocating_node": null
}
],
[
{
"index": "twitter",
"node": "JklnKbD7Tyqi9TP3_Q_tBg",
"primary": true,
"shard": 1,
"state": "STARTED",
"allocation_id": {"id":"fMju3hd1QHWmWrIgFnI4Ww"},
"relocating_node": null
}
]
]
}
--------------------------------------------------
// TESTRESPONSE[s/"nodes": ...,/"nodes": $body.nodes,/]
// TESTRESPONSE[s/JklnKbD7Tyqi9TP3_Q_tBg/$body.shards.0.0.node/]
// TESTRESPONSE[s/0TvkCyF7TAmM1wHP4a42-A/$body.shards.0.0.allocation_id.id/]
// TESTRESPONSE[s/fMju3hd1QHWmWrIgFnI4Ww/$body.shards.1.0.allocation_id.id/]
This time the search will only be executed against two of the shards, because
routing values have been specified.
[float]
=== All parameters:
[horizontal]
`routing`::
A comma-separated list of routing values to take into account when
determining which shards a request would be executed against.
`preference`::
Controls a `preference` of which shard replicas to execute the search
request on. By default, the operation is randomized between the shard
replicas. See the link:search-request-preference.html[preference]
documentation for a list of all acceptable values.
`local`::
A boolean value whether to read the cluster state locally in order to
determine where shards are allocated instead of using the Master node's
cluster state.