InfluxDB: Querying data using the HTTP API

Querying data using the HTTP API

The HTTP API is the primary means for querying data in InfluxDB.

To perform a query send a GET request to the /query endpoint, set the URL parameter db as the target database, and set the URL parameter q as your query. The example below uses the HTTP API to query the same database that you encountered in Writing Data. 

curl -G 'http://localhost:8086/query?pretty=true' --data-urlencode "db=mydb" --data-urlencode "q=SELECT \"value\" FROM \"cpu_load_short\" WHERE \"region\"='us-west'"

InfluxDB returns JSON. The results of your query appear in the "results" array. If an error occurs, InfluxDB sets an "error" key with an explanation of the error. 

{
    "results": [
        {
            "series": [
                {
                    "name": "cpu_load_short",
                    "columns": [
                        "time",
                        "value"
                    ],
                    "values": [
                        [
                            "2015-01-29T21:55:43.702900257Z",
                            0.55
                        ],
                        [
                            "2015-01-29T21:55:43.702900257Z",
                            23422
                        ],
                        [
                            "2015-06-11T20:46:02Z",
                            0.64
                        ]
                    ]
                }
            ]
        }
    ]
}

Note: Appending pretty=true to the URL enables pretty-printed JSON output. While this is useful for debugging or when querying directly with tools like curl, 
it is not recommended for production use as it consumes unnecessary network bandwidth.

Multiple queries

Send multiple queries to InfluxDB in a single API call. Simply delimit each query using a semicolon, for example:

curl -G 'http://localhost:8086/query?pretty=true' --data-urlencode "db=mydb" --data-urlencode "q=SELECT \"value\" FROM \"cpu_load_short\" WHERE \"region\"='us-west';SELECT count(\"value\") FROM \"cpu_load_short\" WHERE \"region\"='us-west'"

returns:

{
    "results": [
        {
            "series": [
                {
                    "name": "cpu_load_short",
                    "columns": [
                        "time",
                        "value"
                    ],
                    "values": [
                        [
                            "2015-01-29T21:55:43.702900257Z",
                            0.55
                        ],
                        [
                            "2015-01-29T21:55:43.702900257Z",
                            23422
                        ],
                        [
                            "2015-06-11T20:46:02Z",
                            0.64
                        ]
                    ]
                }
            ]
        },
        {
            "series": [
                {
                    "name": "cpu_load_short",
                    "columns": [
                        "time",
                        "count"
                    ],
                    "values": [
                        [
                            "1970-01-01T00:00:00Z",
                            3
                        ]
                    ]
                }
            ]
        }
    ]
}

Other options when querying data

Timestamp Format

Everything in InfluxDB is stored and reported in UTC. By default, timestamps are returned in RFC3339 UTC and have nanosecond precision, for example 2015-08-04T19:05:14.318570484Z. If you want timestamps in Unix epoch format include in your request the query string parameter epoch where epoch=[h,m,s,ms,u,ns]. For example, get epoch in seconds with:

curl -G 'http://localhost:8086/query' --data-urlencode "db=mydb" --data-urlencode "epoch=s" --data-urlencode "q=SELECT \"value\" FROM \"cpu_load_short\" WHERE \"region\"='us-west'"

Authentication

Authentication in InfluxDB is disabled by default. See Authentication and Authorization for how to enable and set up authentication.

Maximum Row Limit

InfluxDB will limit the maximum number of returned results to prevent itself from running out of memory while it aggregates the results. This is set to 10,000 by default and can be configured by modifying max-row-limit in the http section of the configuration file.

The maximum row limit only applies to non-chunked queries. Chunked queries can return an unlimited number of points.

Chunking

Chunking can be used to return results in streamed batches rather than as a single response by setting the query string parameter chunked=true. Responses will be chunked by series or by every 10,000 points, whichever occurs first. To change the maximum chunk size to a different value, set the query string parameter chunk_size to a different value. For example, get your results in batches of 20,000 points with:

curl -G 'http://localhost:8086/query' --data-urlencode "db=deluge" --data-urlencode "chunked=true" --data-urlencode "chunk_size=20000" --data-urlencode "q=SELECT * FROM liters"

 

source：https://docs.influxdata.com/influxdb/v1.1/guides/querying_data/