Protocol
For the protocol, SQL plugin provides multiple response formats for different purposes while the request format is same for all. Among them JDBC format is widely used because it provides schema information and more functionality such as pagination. Besides JDBC driver, various clients can benefit from the detailed and well formatted response.
Request Format
Description
The body of HTTP POST request can take a few more other fields with SQL query.
Example 1
Use filter to add more conditions to Elasticsearch DSL directly.
SQL query:
>> curl -H 'Content-Type: application/json' -X POST localhost:9200/_opendistro/_sql -d '{
"query" : "SELECT firstname, lastname, balance FROM accounts",
"filter" : {
"range" : {
"balance" : {
"lt" : 10000
}
}
}
}'
Explain:
{
"from": 0,
"size": 200,
"query": {
"bool": {
"filter": [{
"bool": {
"filter": [{
"range": {
"balance": {
"from": null,
"to": 10000,
"include_lower": true,
"include_upper": false,
"boost": 1.0
}
}
}],
"adjust_pure_negative": true,
"boost": 1.0
}
}],
"adjust_pure_negative": true,
"boost": 1.0
}
},
"_source": {
"includes": [
"firstname",
"lastname",
"balance"
],
"excludes": []
}
}
Example 2
Use parameters for actual parameter value in prepared SQL query.
SQL query:
>> curl -H 'Content-Type: application/json' -X POST localhost:9200/_opendistro/_sql -d '{
"query": "SELECT * FROM accounts WHERE age = ?",
"parameters": [{
"type": "integer",
"value": 30
}]
}'
Explain:
{
"from": 0,
"size": 200,
"query": {
"bool": {
"filter": [{
"bool": {
"must": [{
"term": {
"age": {
"value": 30,
"boost": 1.0
}
}
}],
"adjust_pure_negative": true,
"boost": 1.0
}
}],
"adjust_pure_negative": true,
"boost": 1.0
}
}
}
Elasticsearch DSL
Description
By default the plugin returns original response from Elasticsearch in JSON. Because this is the native response from Elasticsearch, extra efforts are needed to parse and interpret it.
Example
SQL query:
>> curl -H 'Content-Type: application/json' -X POST localhost:9200/_opendistro/_sql -d '{
"query" : "SELECT firstname, lastname, age FROM accounts ORDER BY age LIMIT 2"
}'
Result set:
{
"_shards": {
"total": 5,
"failed": 0,
"successful": 5,
"skipped": 0
},
"hits": {
"hits": [{
"_index": "accounts",
"_type": "account",
"_source": {
"firstname": "Nanette",
"age": 28,
"lastname": "Bates"
},
"_id": "13",
"sort": [
28
],
"_score": null
},
{
"_index": "accounts",
"_type": "account",
"_source": {
"firstname": "Amber",
"age": 32,
"lastname": "Duke"
},
"_id": "1",
"sort": [
32
],
"_score": null
}
],
"total": {
"value": 4,
"relation": "eq"
},
"max_score": null
},
"took": 100,
"timed_out": false
}
JDBC Format
Description
JDBC format is provided for JDBC driver and client side that needs both schema and result set well formatted.
Example 1
Here is an example for normal response. The schema includes field name and its type and datarows includes the result set.
SQL query:
>> curl -H 'Content-Type: application/json' -X POST localhost:9200/_opendistro/_sql?format=jdbc -d '{
"query" : "SELECT firstname, lastname, age FROM accounts ORDER BY age LIMIT 2"
}'
Result set:
{
"schema": [{
"name": "firstname",
"type": "text"
},
{
"name": "lastname",
"type": "text"
},
{
"name": "age",
"type": "long"
}
],
"total": 4,
"datarows": [
[
"Nanette",
"Bates",
28
],
[
"Amber",
"Duke",
32
]
],
"size": 2,
"status": 200
}
Example 2
If any error occurred, error message and the cause will be returned instead.
SQL query:
>> curl -H 'Content-Type: application/json' -X POST localhost:9200/_opendistro/_sql?format=jdbc -d '{
"query" : "SELECT unknown FROM accounts"
}'
Result set:
{
"error": {
"reason": "Invalid SQL query",
"details": "Field [unknown] cannot be found or used here.",
"type": "SemanticAnalysisException"
},
"status": 400
}
CSV Format
Description
You can also use CSV format to download result set as CSV.
Example
SQL query:
>> curl -H 'Content-Type: application/json' -X POST localhost:9200/_opendistro/_sql?format=csv -d '{
"query" : "SELECT firstname, lastname, age FROM accounts ORDER BY age"
}'
Result set:
firstname,lastname,age
Nanette,Bates,28
Amber,Duke,32
Dale,Adams,33
Hattie,Bond,36
Raw Format
Description
Additionally raw format can be used to pipe the result to other command line tool for post processing.
Example
SQL query:
>> curl -H 'Content-Type: application/json' -X POST localhost:9200/_opendistro/_sql?format=raw -d '{
"query" : "SELECT firstname, lastname, age FROM accounts ORDER BY age"
}'
Result set:
Nanette|Bates|28
Amber|Duke|32
Dale|Adams|33
Hattie|Bond|36