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Proposed API consists of 3 endpoints: Query, Status and Result. The latter two are needed only in a case of asynchronous data delivery, while the former is the main endpoint and serves as an entry point for all client requests.

Query Endpoint (/query/service)

The following compares various parameters & HTTP headers using in N1QL API and in current AsterixDB API and proposes parameters to be used in new API.

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N1QL API Parameter

Value

Old Asterix API Parameter

Proposed API Parameter

Comment

statement

string

query

statement

Any valid AQL statement (DDL, update/load statement, FLOWR query), which should be executed

format

enum

Accept HTTP header

both, with the Accept HTTP header overriding the format parameter in case of conflict

[Optional] Desired format for the query results. Possible values are ADM, JSON, CSV. (default: ADM)

signature

boolean

header

signature

[Optional] Defines whether to include a header for the results schema in the response. (default: false)

In case of CSV result format header is included right into the result.

   include-results

[Optional] Defines whether to include results right into the response, or return a handle to retrieve them. (default: true)

-

enum

mode

mode

[Optional] Result delivery mode. Possible values are asynchronous, asynchronous-deferred, synchronous. (default: synchronous)

-

boolean

lossless

lossless

[Optional] Defines whether to use  lossless-JSON output for JSON-encoded output or keep clean-JSON instead. (default: false)

-

boolean

wrapper-array

wrapper-array

[Optional] Defines whether to wrap ADM-encoded output into array-brackets. (default: false)

Used only when format=ADM and include-results=false.

-

boolean

print-expr-tree

expr-tree

[Optional] Defines whether to include an query expression AST into the result (default: false)

-

boolean

print-rewritten-expr-tree

rewritten-expr-tree

[Optional] Defines whether to include a rewritten query expression AST into the result (default: false)

-

boolean

print-logical-plan

logical-plan

[Optional] Defines whether to include a logical plan into the result (default: false)

-

boolean

print-optimized-logical-plan

optimized-plan

[Optional] Defines whether to include a optimized logical plan into the result (default: false)

-

boolean

print-job

hyracks-job

[Optional] Defines whether to include a Hyracks job into the result (default: false)

-

boolean

execute-query

execute-statement

[Optional] Defines whether to execute a statement (default: true)

 

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N1QL API

Value

Old Asterix API

Proposed API Parameter

Comment

results

JSONList

HTTP response body

results

One of 2 possible values

1) A list of all results returned by the query (mode=synchronous and include-results=true).

2) No value (statement is DDL/update/load)

typeString  MIME type of result
-URI-handleA URI to Status endpoint (mode=asynchronous) or the Result endpoint (mode=synchronous and include-results=false)
signatureJSONObject-signatureThe schema of the results (if signature=true & format !=CSV)

status

string

HTTP response status

status

The status of the request; possible values are: success, running (async result), error (parse/optimizer error), fatal (execution error).

error

JSONObject

HTTP response body

error

An object containing details of the error

error.code

int

error-code

error.code

A code that identifies the error.

error.msg

string

summary

error.msg

A message describing the error in detail.

 string

stacktrace

error.stacktrace

A stack trace of the error.

metrics

JSONObject

-

metrics

An object containing details of the execution metrics.

metrics.executionTime

string

-

metrics.executionTime

The time taken for the execution of the request, i.e. time from when query execution started until the results were returned. (if mode=synchronous and execute-query=true)

metrics.resultCount

unsigned int

-

metrics.resultCount

The total number of objects in the results (if mode=synchronous and execute-query=true)

-JSONObject-plans

(Optional) An object containing details of the execution plan at different stages.

-

JSONObject/string

-

plans.expr_tree

Serialized query expression tree (if expr-tree=true)

-

JSONObject/string

-

plans.rewritten_expr_tree

Serialized rewritten query expression tree (if rewritten-expr-tree=true)

-

JSONObject/string

-

plans.logical_plan

Serialized query logical plan (if logical-plan=true)

-

JSONObject/string

-

plans.optimized_plan

Serialized query optimized logical plan (if optimized-plan=true)

-

JSONObject/string

-

plans.hyracks_job

Serialized Hyracks job (if hyracks-job=true)

Examples:

  1. DDL request

    Code Block
    titleRequest
    curl -v http://localhost:19002/query -X POST \
    -d "statement=create dataverse test;"
    Code Block
    titleResponse
    < HTTP/1.1 200 OK
    Content-Type: application/json
    {
      "status": "success"
      "metrics": {
        "executionTime": "1ms"
      }
    }
  2. Query which is not executed, but returns logical plan

    Code Block
    titleRequest
    curl -v http://localhost:19002/query -X POST \
    -d "statement=for $x in dataset testDS return $x & lossless=true & logical-plan=true & execute-query=false"
    Code Block
    titleResponse
    < HTTP/1.1 200 OK
    Content-Type: application/json
    {
      "status": "success"
      "metrics": {
        "executionTime": "5ms"
      },
      "plans": {
        "logical_plan": [
          {"operator": "distribute_result", "args": [{"exp": "var_ref", "var": "$$0"}]},
          {"operator": "datascan", "output_vars": ["$$0", "$$1"]}
        ]
      }
    }
  3. Query which synchronously returns CSV (with header) result inside JSON response

    Code Block
    titleRequest
    curl -v http://localhost:19002/query -X POST -H "Accept: text/csv" \
    -d "statement=for $x in dataset Tweets return $x & signature=true"
    Code Block
    titleResponse
    < HTTP/1.1 200 OK
    Content-Type: application/json
    {
      "status": "success",
      "results": "'id','screen_name','message_text'\n'1','BarackObama','Four more years'"
      "metrics": {
        "executionTime": "10ms",
        "resultCount": 1
      }
    }
  4. Query which returns optimizer error

    Code Block
    titleRequest
    curl -v http://localhost:19002/query -X POST \
    -d "statement=create dataset Tweets(TweetType) primary key facebook_id"
    Code Block
    titleResponse
    < HTTP/1.1 400 Bad Request
    Content-Type: application/json
    {
      "status": "error",
      "error": {
        "code": 1,
        "msg": "Field 'facebook_id' cannot be found in datatype 'TweetType'"
      }
      "metrics": {
        "executionTime": "1ms"
      }
    }
  5. Query which returns runtime error

    Code Block
    titleRequest
    curl -v http://localhost:19002/query -X POST \
    -d "statement=create dataset Tweets(TweetType) primary key facebook_id"
    Code Block
    titleResponse
    < HTTP/1.1 500 Internal Server Error
    Content-Type: application/json
    {
      "status": "fatal",
      "error": {
        "code": 99,
        "msg": "Something happen during query execution",
        "stacktrace": "java.lang.RuntimeException: \n\r at java.lang.Thread.run(Thread.java:745)"
      }
      "metrics": {
        "executionTime": "1ms"
      }
    }
  6. Query which runs synchronously, however does not include them in the response, but provides a handle to retrieve them. Request also specifies to include ADM type (signature). 

    Code Block
    titleRequest
    curl -v http://localhost:19002/query -X POST \
    -d "statement=for $x in dataset Tweets return $x & include-results=false & signature=true"
    Code Block
    titleResponse
    < HTTP/1.1 200 OK
    Content-Type: application/json
    {
      "status": "success",
      "handle": "http://localhost:19002/results/071cde2e-0277-11e6-b512-3e1d05defe78",
      "signature": {
        "id": "int64",
        "screen_name": "string",
        "message_text": "string"
      },
      "metrics": {
        "executionTime": "10ms",
        "resultCount": 2
      }
    }
  7. Query which returns lossless-JSON results asynchronously and does not include them in the response, but provides a handle to retrieve them.

    Code Block
    titleRequest
    curl -v http://localhost:19002/query -X POST -H "Accept: application/json" \
    -d "statement=for $x in dataset Tweets return $x & lossless=true & mode=asynchronous & include-results=false"
    Code Block
    titleResponse
    < HTTP/1.1 200 OK
    Content-Type: application/json
    {
      "status": "running",
      "handle": "http://localhost:19002/status/bd7a2b0e-0277-11e6-b512-3e1d05defe78"
      "metrics": {
      }
    }

Status Endpoint (/query/status)

This endpoint is supposed to be used only in the case when results are delivered asynchronously. The endpoint purpose is solely to inform about status of submitted query, and possibly include results of its execution

...

  1. Query which returns runtime error

    Code Block
    titleRequest
    curl -v http://localhost:19002/status/bd7a2b0e-0277-11e6-b512-3e1d05defe78 -X GET
    Code Block
    titleResponse
    < HTTP/1.1 500 Internal Server Error
    Content-Type: application/json
    {
      "status": "fatal",
      "error": {
        "code": 99,
        "msg": "Something happen during query execution",
        "stacktrace": "java.lang.RuntimeException: \n\r at java.lang.Thread.run(Thread.java:745)"
      }
    }
  2. Query which is still executing

    Code Block
    titleRequest
    curl -v http://localhost:19002/status/bd7a2b0e-0277-11e6-b512-3e1d05defe78 -X GET 
    Code Block
    titleResponse
    < HTTP/1.1 200 OK
    Content-Type: application/json
    {
      "status": "running"
    } 
  3. Query which successfully completes and return URI to its results. Reffer to Query endpoint Example 7 to see the original request.

    Code Block
    titleRequest
    curl -v http://localhost:19002/status/bd7a2b0e-0277-11e6-b512-3e1d05defe78 -X GET
    Code Block
    titleResponse
    < HTTP/1.1 200 OK
    Content-Type: application/json
    {
      "status": "success",
      "handle": "http://localhost:19002/results/c7e7daed-28cd-472f-890d-62e02909e5e9"
      "metrics": {
        "executionTime": 100ms,
        "resultCount": 10
      }
    }  

Result Endpoint (/query/result)

This endpoint is used to retrieve results of asynchronous query execution or synchronous results, when the client opted out from having results included into /query request (include-results=false).

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