Table of contents
Full-text search is for searching a single stored document which is distinguished from regular search based on original texts in database. It tries to match search criteria by examining all of the words in each document. In Elasticsearch, full-text queries provided enables you to search text fields analyzed during indexing.
Match query is the standard query for full-text search in Elasticsearch. Both MATCHQUERY and MATCH_QUERY are functions for performing match query.
Both functions can accept field name as first argument and a text as second argument.
SQL query:
POST /_opendistro/_sql
{
"query" : """
SELECT account_number, address
FROM accounts
WHERE MATCH_QUERY(address, 'Holmes')
"""
}
Explain:
{
"from" : 0,
"size" : 200,
"query" : {
"bool" : {
"filter" : [
{
"bool" : {
"must" : [
{
"match" : {
"address" : {
"query" : "Holmes",
"operator" : "OR",
"prefix_length" : 0,
"max_expansions" : 50,
"fuzzy_transpositions" : true,
"lenient" : false,
"zero_terms_query" : "NONE",
"auto_generate_synonyms_phrase_query" : true,
"boost" : 1.0
}
}
}
],
"adjust_pure_negative" : true,
"boost" : 1.0
}
}
],
"adjust_pure_negative" : true,
"boost" : 1.0
}
},
"_source" : {
"includes" : [
"account_number",
"address"
],
"excludes" : [ ]
}
}
Result set:
| account_number | address |
|---|---|
| 1 | 880 Holmes Lane |
Both functions can also accept single argument and be used in the following manner.
SQL query:
POST /_opendistro/_sql
{
"query" : """
SELECT account_number, address
FROM accounts
WHERE address = MATCH_QUERY('Holmes')
"""
}
Explain:
{
"from" : 0,
"size" : 200,
"query" : {
"bool" : {
"filter" : [
{
"bool" : {
"must" : [
{
"match" : {
"address" : {
"query" : "Holmes",
"operator" : "OR",
"prefix_length" : 0,
"max_expansions" : 50,
"fuzzy_transpositions" : true,
"lenient" : false,
"zero_terms_query" : "NONE",
"auto_generate_synonyms_phrase_query" : true,
"boost" : 1.0
}
}
}
],
"adjust_pure_negative" : true,
"boost" : 1.0
}
}
],
"adjust_pure_negative" : true,
"boost" : 1.0
}
},
"_source" : {
"includes" : [
"account_number",
"address"
],
"excludes" : [ ]
}
}
Result set:
| account_number | address |
|---|---|
| 1 | 880 Holmes Lane |
Besides match query against a single field, you can search for a text with multiple fields. Function MULTI_MATCH, MULTIMATCH and MULTIMATCHQUERY are provided for this.
Each preceding function accepts query for a text and fields for field names or pattern that the text given is searched against. For example, the following query is searching for documents in index accounts with 'Dale' as either firstname or lastname.
SQL query:
POST /_opendistro/_sql
{
"query" : """
SELECT firstname, lastname
FROM accounts
WHERE MULTI_MATCH('query'='Dale', 'fields'='*name')
"""
}
Explain:
{
"from" : 0,
"size" : 200,
"query" : {
"bool" : {
"filter" : [
{
"bool" : {
"must" : [
{
"multi_match" : {
"query" : "Dale",
"fields" : [
"*name^1.0"
],
"type" : "best_fields",
"operator" : "OR",
"slop" : 0,
"prefix_length" : 0,
"max_expansions" : 50,
"zero_terms_query" : "NONE",
"auto_generate_synonyms_phrase_query" : true,
"fuzzy_transpositions" : true,
"boost" : 1.0
}
}
],
"adjust_pure_negative" : true,
"boost" : 1.0
}
}
],
"adjust_pure_negative" : true,
"boost" : 1.0
}
},
"_source" : {
"includes" : [
"firstname",
"lastname"
],
"excludes" : [ ]
}
}
Result set:
| firstname | lastname |
|---|---|
| Dale | Adams |
Query string query parses and splits a query string provided based on Lucene query string syntax. The mini language supports logical connectives, wildcard, regex and proximity search. Please refer to official documentation for more details. Note that an error is thrown in the case of any invalid syntax in query string.
QUERY function accepts query string and returns true or false respectively for document that matches the query string or not.
SQL query:
POST /_opendistro/_sql
{
"query" : """
SELECT account_number, address
FROM accounts
WHERE QUERY('address:Lane OR address:Street')
"""
}
Explain:
{
"from" : 0,
"size" : 200,
"query" : {
"bool" : {
"filter" : [
{
"bool" : {
"must" : [
{
"query_string" : {
"query" : "address:Lane OR address:Street",
"fields" : [ ],
"type" : "best_fields",
"default_operator" : "or",
"max_determinized_states" : 10000,
"enable_position_increments" : true,
"fuzziness" : "AUTO",
"fuzzy_prefix_length" : 0,
"fuzzy_max_expansions" : 50,
"phrase_slop" : 0,
"escape" : false,
"auto_generate_synonyms_phrase_query" : true,
"fuzzy_transpositions" : true,
"boost" : 1.0
}
}
],
"adjust_pure_negative" : true,
"boost" : 1.0
}
}
],
"adjust_pure_negative" : true,
"boost" : 1.0
}
},
"_source" : {
"includes" : [
"account_number",
"address"
],
"excludes" : [ ]
}
}
Result set:
| account_number | address |
|---|---|
| 1 | 880 Holmes Lane |
| 6 | 671 Bristol Street |
| 13 | 789 Madison Street |
Match phrase query is similar to match query but it is used for matching exact phrases. MATCHPHRASE, MATCH_PHRASE and MATCHPHRASEQUERY are provided for this purpose.
SQL query:
POST /_opendistro/_sql
{
"query" : """
SELECT account_number, address
FROM accounts
WHERE MATCH_PHRASE(address, '880 Holmes Lane')
"""
}
Explain:
{
"from" : 0,
"size" : 200,
"query" : {
"bool" : {
"filter" : [
{
"bool" : {
"must" : [
{
"match_phrase" : {
"address" : {
"query" : "880 Holmes Lane",
"slop" : 0,
"zero_terms_query" : "NONE",
"boost" : 1.0
}
}
}
],
"adjust_pure_negative" : true,
"boost" : 1.0
}
}
],
"adjust_pure_negative" : true,
"boost" : 1.0
}
},
"_source" : {
"includes" : [
"account_number",
"address"
],
"excludes" : [ ]
}
}
Result set:
| account_number | address |
|---|---|
| 1 | 880 Holmes Lane |
Elasticsearch supports to wrap a filter query so as to return a relevance score along with every matching document. SCORE, SCOREQUERY and SCORE_QUERY can be used for this.
The first argument is a match query expression and the second argument is for an optional floating point number to boost the score. The default value is 1.0. Apart from this, an implicit variable _score is available so you can return score for each document or use it for sorting.
SQL query:
POST /_opendistro/_sql
{
"query" : """
SELECT account_number, address, _score
FROM accounts
WHERE SCORE(MATCH_QUERY(address, 'Lane'), 0.5) OR
SCORE(MATCH_QUERY(address, 'Street'), 100)
ORDER BY _score
"""
}
Explain:
{
"from" : 0,
"size" : 200,
"query" : {
"bool" : {
"must" : [
{
"bool" : {
"should" : [
{
"constant_score" : {
"filter" : {
"match" : {
"address" : {
"query" : "Lane",
"operator" : "OR",
"prefix_length" : 0,
"max_expansions" : 50,
"fuzzy_transpositions" : true,
"lenient" : false,
"zero_terms_query" : "NONE",
"auto_generate_synonyms_phrase_query" : true,
"boost" : 1.0
}
}
},
"boost" : 0.5
}
},
{
"constant_score" : {
"filter" : {
"match" : {
"address" : {
"query" : "Street",
"operator" : "OR",
"prefix_length" : 0,
"max_expansions" : 50,
"fuzzy_transpositions" : true,
"lenient" : false,
"zero_terms_query" : "NONE",
"auto_generate_synonyms_phrase_query" : true,
"boost" : 1.0
}
}
},
"boost" : 100.0
}
}
],
"adjust_pure_negative" : true,
"boost" : 1.0
}
}
],
"adjust_pure_negative" : true,
"boost" : 1.0
}
},
"_source" : {
"includes" : [
"account_number",
"address",
"_score"
],
"excludes" : [ ]
},
"sort" : [
{
"_score" : {
"order" : "asc"
}
}
]
}
Result set:
| account_number | address | _score |
|---|---|---|
| 1 | 880 Holmes Lane | 0.5 |
| 6 | 671 Bristol Street | 100 |
| 13 | 789 Madison Street | 100 |