If you first install, use CREATE EXTENSION http.

If you already installed a previous version and you just want to upgrade, then ALTER EXTENSION http UPDATE.

Every HTTP call is a made up of an http_request and an http_response.

                     Composite type "public.http_request"

                    Column    |       Type        | Modifiers
                --------------+-------------------+-----------
                 method       | http_method       |
                 uri          | character varying |
                 headers      | http_header[]     |
                 content_type | character varying |
                 content      | character varying |

                    Composite type "public.http_response"
                    Column    |       Type        | Modifiers
                --------------+-------------------+-----------
                 status       | integer           |
                 content_type | character varying |
                 headers      | http_header[]     |
                 content      | character varying |
        

The utility functions, http_get(), http_post(), http_put(), http_delete() and http_head() are just wrappers around a master function, http(http_request) that returns http_response.

The headers field for requests and response is a LightDB array of type http_header which is just a simple tuple.

                  Composite type "public.http_header"
                 Column |       Type        | Modifiers
                --------+-------------------+-----------
                 field  | character varying |
                 value  | character varying |
        

As seen in the examples, you can unspool the array of http_header tuples into a result set using the LightDB unnest() function on the array. From there you select out the particular header you are interested in.

Select CURL options are available to set using the http_set_curlopt(curlopt VARCHAR, value varchar) function.

The http_reset_curlopt() approach described above is recommended. The global variables below will be deprecated and removed over time.

By default each request uses a fresh connection and assures that the connection is closed when the request is done. This behavior reduces the chance of consuming system resources (sockets) as the extension runs over extended periods of time.

High-performance applications may wish to enable keep-alive and connection persistence to reduce latency and enhance throughput. The following GUC variable changes the behavior of the http extension to maintain connections as long as possible:

            http.keepalive = 'on'
        

By default a 60 second timeout is set for the completion of a request. If a different timeout is desired the following GUC variable can be used to set it in milliseconds:

            http.timeout_msec = 60000
        

            -- URL encode a string.

            SELECT urlencode('my special string''s and things?');


                          urlencode
            -------------------------------------
             my+special+string%27s+and+things%3F
            (1 row)


            -- URL encode a JSON associative array.

            SELECT urlencode(jsonb_build_object('name','Colin and James'));


                          urlencode
            -------------------------------------
               name=Colin+and+James
            (1 row)


            -- Run a GET request and see the content.

            SELECT content
              FROM http_get('http://httpbin.org/ip');


                       content
            -----------------------------
             {"origin":"24.69.186.43"}                          +
            (1 row)


            -- Run a GET request with an Authorization header.

            SELECT content::json->'headers'->>'Authorization'
              FROM http((
                      'GET',
                       'http://httpbin.org/headers',
                       ARRAY[http_header('Authorization','Bearer eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9')],
                       NULL,
                       NULL
                    )::http_request);


                               content
            ----------------------------------------------
             Bearer eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9
            (1 row)


            -- Read the status and content fields out of a http_response object.

            SELECT status, content_type
              FROM http_get('http://httpbin.org/');


             status |       content_type
            --------+--------------------------
                200 | text/html; charset=utf-8
            (1 row)

            -- Show all the http_header in an http_response object.


            SELECT (unnest(headers)).*
              FROM http_get('http://httpbin.org/');

                          field               |             value
            ----------------------------------+-------------------------------
             Connection                       | close
             Server                           | meinheld/0.6.1
             Date                             | Tue, 09 Jan 2018 18:40:30 GMT
             Content-Type                     | text/html; charset=utf-8
             Content-Length                   | 13011
             Access-Control-Allow-Origin      | *
             Access-Control-Allow-Credentials | true
             X-Powered-By                     | Flask
             X-Processed-Time                 | 0.0208520889282
             Via                              | 1.1 vegur


            -- Use the PUT command to send a simple text document to a server.

            SELECT status, content_type, content::json->>'data' AS data
              FROM http_put('http://httpbin.org/put', 'some text', 'text/plain');


             status |   content_type   |   data
            --------+------------------+-----------
                200 | application/json | some text

            -- Use the PATCH command to send a simple JSON document to a server.

            SELECT status, content_type, content::json->>'data' AS data
              FROM http_patch('http://httpbin.org/patch', '{"this":"that"}', 'application/json');

             status |   content_type   |      data
            --------+------------------+------------------
                200 | application/json | '{"this":"that"}'


            -- Use the DELETE command to request resource deletion.

            SELECT status, content_type, content::json->>'url' AS url
              FROM http_delete('http://httpbin.org/delete');


             status |   content_type   |            url
            --------+------------------+---------------------------
                200 | application/json | http://httpbin.org/delete

            -- As a shortcut to send data to a GET request, pass a JSONB data argument.

            SELECT status, content::json->'args' AS args
              FROM http_get('http://httpbin.org/get',
                            jsonb_build_object('myvar','myval','foo','bar'));

            -- To POST to a URL using a data payload instead of parameters embedded in the URL, encode the data in a JSONB as a data payload.

            SELECT status, content::json->'form' AS form
              FROM http_post('http://httpbin.org/post',
                             jsonb_build_object('myvar','myval','foo','bar'));

            -- To access binary content, you must coerce the content from the default varchar representation to a bytea representation using the textsend function. Using the default varchar::bytea cast will not work, as the cast will stop the first time it hits a zero-valued byte (common in binary data).

            WITH
              http AS (
                SELECT * FROM http_get('http://httpbin.org/image/png')
              ),
              headers AS (
                SELECT (unnest(headers)).* FROM http
              )
            SELECT
              http.content_type,
              length(textsend(http.content)) AS length_binary,
              headers.value AS length_headers
            FROM http, headers
            WHERE field = 'Content-Length';

             content_type | length_binary | length_headers
            --------------+---------------+----------------
             image/png    |          8090 | 8090