301 lines
8.9 KiB
Plaintext
301 lines
8.9 KiB
Plaintext
[[query-dsl-intervals-query]]
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=== Intervals query
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An `intervals` query allows fine-grained control over the order and proximity of
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matching terms. Matching rules are constructed from a small set of definitions,
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and the rules are then applied to terms from a particular `field`.
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The definitions produce sequences of minimal intervals that span terms in a
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body of text. These intervals can be further combined and filtered by
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parent sources.
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The example below will search for the phrase `my favourite food` appearing
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before the terms `hot` and `water` or `cold` and `porridge` in any order, in
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the field `my_text`
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[source,js]
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--------------------------------------------------
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POST _search
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{
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"query": {
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"intervals" : {
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"my_text" : {
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"all_of" : {
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"ordered" : true,
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"intervals" : [
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{
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"match" : {
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"query" : "my favourite food",
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"max_gaps" : 0,
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"ordered" : true
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}
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},
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{
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"any_of" : {
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"intervals" : [
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{ "match" : { "query" : "hot water" } },
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{ "match" : { "query" : "cold porridge" } }
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]
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}
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}
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]
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},
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"_name" : "favourite_food"
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}
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}
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}
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}
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--------------------------------------------------
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// CONSOLE
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In the above example, the text `my favourite food is cold porridge` would
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match because the two intervals matching `my favourite food` and `cold
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porridge` appear in the correct order, but the text `when it's cold my
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favourite food is porridge` would not match, because the interval matching
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`cold porridge` starts before the interval matching `my favourite food`.
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[[intervals-match]]
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==== `match`
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The `match` rule matches analyzed text, and takes the following parameters:
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[horizontal]
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`query`::
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The text to match.
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`max_gaps`::
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Specify a maximum number of gaps between the terms in the text. Terms that
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appear further apart than this will not match. If unspecified, or set to -1,
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then there is no width restriction on the match. If set to 0 then the terms
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must appear next to each other.
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`ordered`::
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Whether or not the terms must appear in their specified order. Defaults to
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`false`
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`analyzer`::
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Which analyzer should be used to analyze terms in the `query`. By
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default, the search analyzer of the top-level field will be used.
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`filter`::
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An optional <<interval_filter,interval filter>>
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`use_field`::
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If specified, then match intervals from this field rather than the top-level field.
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Terms will be analyzed using the search analyzer from this field. This allows you
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to search across multiple fields as if they were all the same field; for example,
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you could index the same text into stemmed and unstemmed fields, and search for
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stemmed tokens near unstemmed ones.
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[[intervals-all_of]]
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==== `all_of`
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`all_of` returns returns matches that span a combination of other rules.
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[horizontal]
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`intervals`::
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An array of rules to combine. All rules must produce a match in a
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document for the overall source to match.
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`max_gaps`::
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Specify a maximum number of gaps between the rules. Combinations that match
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across a distance greater than this will not match. If set to -1 or
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unspecified, there is no restriction on this distance. If set to 0, then the
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matches produced by the rules must all appear immediately next to each other.
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`ordered`::
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Whether the intervals produced by the rules should appear in the order in
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which they are specified. Defaults to `false`
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`filter`::
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An optional <<interval_filter,interval filter>>
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[[intervals-any_of]]
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==== `any_of`
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The `any_of` rule emits intervals produced by any of its sub-rules.
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[horizontal]
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`intervals`::
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An array of rules to match
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`filter`::
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An optional <<interval_filter,interval filter>>
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[[interval_filter]]
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==== filters
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You can filter intervals produced by any rules by their relation to the
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intervals produced by another rule. The following example will return
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documents that have the words `hot` and `porridge` within 10 positions
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of each other, without the word `salty` in between:
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[source,js]
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--------------------------------------------------
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POST _search
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{
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"query": {
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"intervals" : {
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"my_text" : {
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"match" : {
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"query" : "hot porridge",
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"max_gaps" : 10,
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"filter" : {
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"not_containing" : {
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"match" : {
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"query" : "salty"
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}
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}
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}
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}
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}
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}
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}
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}
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--------------------------------------------------
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// CONSOLE
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The following filters are available:
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[horizontal]
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`containing`::
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Produces intervals that contain an interval from the filter rule
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`contained_by`::
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Produces intervals that are contained by an interval from the filter rule
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`not_containing`::
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Produces intervals that do not contain an interval from the filter rule
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`not_contained_by`::
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Produces intervals that are not contained by an interval from the filter rule
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`overlapping`::
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Produces intervals that overlap with an interval from the filter rule
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`not_overlapping`::
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Produces intervals that do not overlap with an interval from the filter rule
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`before`::
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Produces intervals that appear before an interval from the filter role
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`after`::
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Produces intervals that appear after an interval from the filter role
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[[interval-script-filter]]
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==== Script filters
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You can also filter intervals based on their start position, end position and
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internal gap count, using a script. The script has access to an `interval`
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variable, with `start`, `end` and `gaps` methods:
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[source,js]
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--------------------------------------------------
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POST _search
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{
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"query": {
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"intervals" : {
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"my_text" : {
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"match" : {
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"query" : "hot porridge",
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"filter" : {
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"script" : {
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"source" : "interval.start > 10 && interval.end < 20 && interval.gaps == 0"
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}
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}
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}
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}
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}
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}
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}
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--------------------------------------------------
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// CONSOLE
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[[interval-minimization]]
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==== Minimization
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The intervals query always minimizes intervals, to ensure that queries can
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run in linear time. This can sometimes cause surprising results, particularly
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when using `max_gaps` restrictions or filters. For example, take the
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following query, searching for `salty` contained within the phrase `hot
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porridge`:
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[source,js]
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--------------------------------------------------
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POST _search
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{
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"query": {
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"intervals" : {
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"my_text" : {
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"match" : {
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"query" : "salty",
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"filter" : {
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"contained_by" : {
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"match" : {
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"query" : "hot porridge"
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}
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}
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}
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}
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}
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}
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}
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}
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--------------------------------------------------
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// CONSOLE
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This query will *not* match a document containing the phrase `hot porridge is
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salty porridge`, because the intervals returned by the match query for `hot
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porridge` only cover the initial two terms in this document, and these do not
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overlap the intervals covering `salty`.
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Another restriction to be aware of is the case of `any_of` rules that contain
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sub-rules which overlap. In particular, if one of the rules is a strict
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prefix of the other, then the longer rule will never be matched, which can
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cause surprises when used in combination with `max_gaps`. Consider the
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following query, searching for `the` immediately followed by `big` or `big bad`,
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immediately followed by `wolf`:
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[source,js]
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--------------------------------------------------
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POST _search
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{
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"query": {
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"intervals" : {
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"my_text" : {
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"all_of" : {
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"intervals" : [
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{ "match" : { "query" : "the" } },
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{ "any_of" : {
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"intervals" : [
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{ "match" : { "query" : "big" } },
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{ "match" : { "query" : "big bad" } }
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] } },
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{ "match" : { "query" : "wolf" } }
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],
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"max_gaps" : 0,
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"ordered" : true
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}
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}
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}
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}
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}
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--------------------------------------------------
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// CONSOLE
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Counter-intuitively, this query *will not* match the document `the big bad
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wolf`, because the `any_of` rule in the middle will only produce intervals
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for `big` - intervals for `big bad` being longer than those for `big`, while
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starting at the same position, and so being minimized away. In these cases,
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it's better to rewrite the query so that all of the options are explicitly
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laid out at the top level:
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[source,js]
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--------------------------------------------------
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POST _search
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{
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"query": {
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"intervals" : {
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"my_text" : {
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"any_of" : {
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"intervals" : [
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{ "match" : {
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"query" : "the big bad wolf",
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"ordered" : true,
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"max_gaps" : 0 } },
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{ "match" : {
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"query" : "the big wolf",
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"ordered" : true,
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"max_gaps" : 0 } }
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]
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}
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}
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}
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}
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}
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--------------------------------------------------
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// CONSOLE
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