158 lines
6.2 KiB
Plaintext
158 lines
6.2 KiB
Plaintext
[role="xpack"]
|
|
[testenv="basic"]
|
|
[[sql-functions-search]]
|
|
=== Full-Text Search Functions
|
|
|
|
Search functions should be used when performing full-text search, namely
|
|
when the `MATCH` or `QUERY` predicates are being used.
|
|
Outside a, so-called, search context, these functions will return default values
|
|
such as `0` or `NULL`.
|
|
|
|
[[sql-functions-search-match]]
|
|
==== `MATCH`
|
|
|
|
.Synopsis:
|
|
[source, sql]
|
|
--------------------------------------------------
|
|
MATCH(field_exp<1>, constant_exp<2>[, options]<3>)
|
|
--------------------------------------------------
|
|
|
|
*Input*:
|
|
|
|
<1> field(s) to match
|
|
<2> matching text
|
|
<3> additional parameters; optional
|
|
|
|
.Description:
|
|
|
|
A full-text search option, in the form of a predicate, available in {es-sql} that gives the user control over powerful <<query-dsl-match-query,match>>
|
|
and <<query-dsl-multi-match-query,multi_match>> {es} queries.
|
|
|
|
The first parameter is the field or fields to match against. In case it receives one value only, {es-sql} will use a `match` query to perform the search:
|
|
|
|
["source","sql",subs="attributes,callouts,macros"]
|
|
----
|
|
include-tagged::{sql-specs}/docs/docs.csv-spec[simpleMatch]
|
|
----
|
|
|
|
However, it can also receive a list of fields and their corresponding optional `boost` value. In this case, {es-sql} will use a
|
|
`multi_match` query to match the documents:
|
|
|
|
["source","sql",subs="attributes,callouts,macros"]
|
|
----
|
|
include-tagged::{sql-specs}/docs/docs.csv-spec[multiFieldsMatch]
|
|
----
|
|
|
|
NOTE: The `multi_match` query in {es} has the option of <<query-dsl-multi-match-query,per-field boosting>> that gives preferential weight
|
|
(in terms of scoring) to fields being searched in, using the `^` character. In the example above, the `name` field has a greater weight in
|
|
the final score than the `author` field when searching for `frank dune` text in both of them.
|
|
|
|
Both options above can be used in combination with the optional third parameter of the `MATCH()` predicate, where one can specify
|
|
additional configuration parameters (separated by semicolon `;`) for either `match` or `multi_match` queries. For example:
|
|
|
|
["source","sql",subs="attributes,callouts,macros"]
|
|
----
|
|
include-tagged::{sql-specs}/docs/docs.csv-spec[optionalParamsForMatch]
|
|
----
|
|
|
|
In the more advanced example above, the `cutoff_frequency` parameter allows specifying an absolute or relative document frequency where
|
|
high frequency terms are moved into an optional subquery and are only scored if one of the low frequency (below the cutoff) terms in the
|
|
case of an `or` operator or all of the low frequency terms in the case of an `and` operator match. More about this you can find in the
|
|
<<query-dsl-match-query-cutoff>> page.
|
|
|
|
NOTE: The allowed optional parameters for a single-field `MATCH()` variant (for the `match` {es} query) are: `analyzer`, `auto_generate_synonyms_phrase_query`,
|
|
`cutoff_frequency`, `lenient`, `fuzzy_transpositions`, `fuzzy_rewrite`, `minimum_should_match`, `operator`,
|
|
`max_expansions`, `prefix_length`.
|
|
|
|
NOTE: The allowed optional parameters for a multi-field `MATCH()` variant (for the `multi_match` {es} query) are: `analyzer`, `auto_generate_synonyms_phrase_query`,
|
|
`cutoff_frequency`, `lenient`, `fuzzy_transpositions`, `fuzzy_rewrite`, `minimum_should_match`, `operator`,
|
|
`max_expansions`, `prefix_length`, `slop`, `tie_breaker`, `type`.
|
|
|
|
|
|
[[sql-functions-search-query]]
|
|
==== `QUERY`
|
|
|
|
.Synopsis:
|
|
[source, sql]
|
|
--------------------------------------------------
|
|
QUERY(constant_exp<1>[, options]<2>)
|
|
--------------------------------------------------
|
|
|
|
*Input*:
|
|
|
|
<1> query text
|
|
<2> additional parameters; optional
|
|
|
|
.Description:
|
|
|
|
Just like `MATCH`, `QUERY` is a full-text search predicate that gives the user control over the <<query-dsl-query-string-query,query_string>> query in {es}.
|
|
|
|
The first parameter is basically the input that will be passed as is to the `query_string` query, which means that anything that `query_string`
|
|
accepts in its `query` field can be used here as well:
|
|
|
|
["source","sql",subs="attributes,callouts,macros"]
|
|
----
|
|
include-tagged::{sql-specs}/docs/docs.csv-spec[simpleQueryQuery]
|
|
----
|
|
|
|
A more advanced example, showing more of the features that `query_string` supports, of course possible with {es-sql}:
|
|
|
|
["source","sql",subs="attributes,callouts,macros"]
|
|
----
|
|
include-tagged::{sql-specs}/docs/docs.csv-spec[advancedQueryQuery]
|
|
----
|
|
|
|
The query above uses the `_exists_` query to select documents that have values in the `author` field, a range query for `page_count` and
|
|
regex and fuzziness queries for the `name` field.
|
|
|
|
If one needs to customize various configuration options that `query_string` exposes, this can be done using the second _optional_ parameter.
|
|
Multiple settings can be specified separated by a semicolon `;`:
|
|
|
|
["source","sql",subs="attributes,callouts,macros"]
|
|
----
|
|
include-tagged::{sql-specs}/docs/docs.csv-spec[optionalParameterQuery]
|
|
----
|
|
|
|
NOTE: The allowed optional parameters for `QUERY()` are: `allow_leading_wildcard`, `analyze_wildcard`, `analyzer`,
|
|
`auto_generate_synonyms_phrase_query`, `default_field`, `default_operator`, `enable_position_increments`,
|
|
`escape`, `fuzzy_max_expansions`, `fuzzy_prefix_length`, `fuzzy_rewrite`, `fuzzy_transpositions`, `lenient`,
|
|
`locale`, `lowercase_expanded_terms`, `max_determinized_states`, `minimum_should_match`, `phrase_slop`, `rewrite`,
|
|
`quote_analyzer`, `quote_field_suffix`, `tie_breaker`, `time_zone`, `type`.
|
|
|
|
|
|
[[sql-functions-search-score]]
|
|
==== `SCORE`
|
|
|
|
.Synopsis:
|
|
[source, sql]
|
|
--------------------------------------------------
|
|
SCORE()
|
|
--------------------------------------------------
|
|
|
|
*Input*: _none_
|
|
|
|
*Output*: `double` numeric value
|
|
|
|
.Description:
|
|
|
|
Returns the {defguide}/relevance-intro.html[relevance] of a given input to the executed query.
|
|
The higher score, the more relevant the data.
|
|
|
|
NOTE: When doing multiple text queries in the `WHERE` clause then, their scores will be
|
|
combined using the same rules as {es}'s
|
|
<<query-dsl-bool-query,bool query>>.
|
|
|
|
Typically `SCORE` is used for ordering the results of a query based on their relevance:
|
|
|
|
["source","sql",subs="attributes,callouts,macros"]
|
|
----
|
|
include-tagged::{sql-specs}/docs/docs.csv-spec[orderByScore]
|
|
----
|
|
|
|
However, it is perfectly fine to return the score without sorting by it:
|
|
|
|
["source","sql",subs="attributes,callouts,macros"]
|
|
----
|
|
include-tagged::{sql-specs}/docs/docs.csv-spec[scoreWithMatch]
|
|
----
|