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325 lines
7.8 KiB
ReStructuredText
325 lines
7.8 KiB
ReStructuredText
.. meta::
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:description: Execute SQL with the Hasura schema/metadata API
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:keywords: hasura, docs, schema/metadata API, API reference, run_sql
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.. _schema_api_run_sql:
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Schema API Reference: Run SQL (v2.0 and above)
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==============================================
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.. contents:: Table of contents
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:backlinks: none
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:depth: 2
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:local:
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.. _schema_run_sql:
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run_sql
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-------
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``run_sql`` can be used to run arbitrary SQL statements.
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Multiple SQL statements can be separated by a ``;``, however, only the result of the last SQL statement will be
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returned.
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.. admonition:: Admin-only
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This is an admin-only request, i.e. the request can only be executed with ``X-Hasura-Role: admin``. This can be set by passing
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``X-Hasura-Admin-Secret`` or by setting the right role in webhook/JWT
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authorization mode.
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This is deliberate as it is hard to enforce any sort of permissions on arbitrary SQL. If
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you find yourself in the need of using ``run_sql`` to run custom DML requests,
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consider creating a view. You can now define permissions on that particular view
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for various roles.
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.. admonition:: Supported from
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The schema API is supported for versions ``v2.0.0`` and above and replaces the older
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:ref:`schema/metadata API <schema_metadata_apis>`.
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Use cases
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^^^^^^^^^
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1. To execute DDL operations that are not supported by the console (e.g. managing indexes).
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2. Run custom DML requests from backend microservices instead of installing libraries to speak to Postgres.
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An example:
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.. code-block:: http
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POST /v2/query HTTP/1.1
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Content-Type: application/json
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X-Hasura-Role: admin
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{
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"type": "run_sql",
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"args": {
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"source": "default",
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"sql": "CREATE UNIQUE INDEX ON films (title);"
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}
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}
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While ``run_sql`` lets you run any SQL, it tries to ensure that the Hasura GraphQL engine's
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state (relationships, permissions etc.) is consistent i.e. you
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cannot drop a column on which any metadata is dependent on (say a permission or
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a relationship). The effects, however, can be cascaded.
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Example: If we were to drop the 'bio' column from the author table (let's say
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the column is used in some permission), you would see an error.
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.. code-block:: http
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POST /v2/query HTTP/1.1
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Content-Type: application/json
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X-Hasura-Role: admin
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{
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"type": "run_sql",
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"args": {
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"source": "default",
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"sql": "ALTER TABLE author DROP COLUMN name"
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}
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}
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.. code-block:: http
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HTTP/1.1 400 BAD REQUEST
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Content-Type: application/json
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{
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"path": "$.args",
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"error": "cannot drop due to the following dependent objects : permission author.user.select"
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}
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We can however, cascade these changes.
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.. code-block:: http
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:emphasize-lines: 9
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POST /v2/query HTTP/1.1
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Content-Type: application/json
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X-Hasura-Role: admin
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{
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"type": "run_sql",
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"args": {
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"source": "default",
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"sql": "ALTER TABLE author DROP COLUMN bio",
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"cascade" : true
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}
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}
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.. code-block:: http
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HTTP/1.1 200 OK
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Content-Type: application/json
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{
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"result_type": "CommandOk"
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}
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With the above request, the dependent permission is also dropped.
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Example: If we were to drop a foreign key constraint from the article table
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(let's say the column involved in the foreign key is used to define a relationship),
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you would see an error.
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.. code-block:: http
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POST /v2/query HTTP/1.1
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Content-Type: application/json
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X-Hasura-Role: admin
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{
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"type": "run_sql",
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"args": {
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"source": "default",
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"sql": "ALTER TABLE article DROP CONSTRAINT article_author_id_fkey"
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}
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}
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.. code-block:: http
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HTTP/1.1 400 BAD REQUEST
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Content-Type: application/json
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{
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"path": "$.args",
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"error": "cannot drop due to the following dependent objects : constraint article.article_author_id_fkey"
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}
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We can however, cascade these changes.
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.. code-block:: http
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:emphasize-lines: 9
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POST /v2/query HTTP/1.1
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Content-Type: application/json
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X-Hasura-Role: admin
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{
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"type": "run_sql",
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"args": {
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"source": "default",
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"sql": "ALTER TABLE article DROP CONSTRAINT article_author_id_fkey",
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"cascade" : true
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}
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}
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.. code-block:: http
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HTTP/1.1 200 OK
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Content-Type: application/json
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{
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"result_type": "CommandOk"
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}
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With the above request, the dependent permission is also dropped.
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In general, the SQL operations that will affect Hasura metadata are:
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1. Dropping columns
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2. Dropping tables
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3. Dropping foreign keys
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4. Altering types of columns
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5. Dropping SQL functions
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6. Overloading SQL functions
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In case of 1, 2 and 3 the dependent objects (if any) can be dropped using ``cascade``.
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However, when altering type of columns, if any objects are affected, the change
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cannot be cascaded. So, those dependent objects have to be manually dropped before
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executing the SQL statement. Dropping SQL functions will cascade the functions in
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metadata even without using ``cascade`` since no other objects depend on them.
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Overloading tracked SQL functions is not allowed.
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Set ``check_metadata_consistency`` field to ``false`` to force the server to not consider metadata dependencies.
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.. _schema_run_sql_syntax:
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Args syntax
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^^^^^^^^^^^
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.. list-table::
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:header-rows: 1
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* - Key
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- Required
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- Schema
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- Description
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* - sql
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- true
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- String
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- The sql to be executed
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* - source
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- false
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- String
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- The database on which the sql is to be executed (default: 'default' database)
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* - cascade
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- false
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- Boolean
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- When set to ``true``, the effect (if possible) is cascaded to any hasuradb dependent objects (relationships, permissions, templates).
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* - check_metadata_consistency
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- false
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- Boolean
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- When set to ``false``, the sql is executed without checking metadata dependencies.
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* - read_only
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- false
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- Boolean
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- When set to ``true``, the request will be run in ``READ ONLY`` transaction access mode which means only ``select`` queries will be successful. This flag ensures that the GraphQL schema is not modified and is hence highly performant.
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Response
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^^^^^^^^
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The response is a JSON Object with the following structure.
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.. list-table::
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:header-rows: 1
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* - Key
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- Always present
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- Schema
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- Description
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* - result_type
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- true
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- String
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- One of "CommandOk" or "TuplesOk"
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* - result
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- false
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- ``[[Text]]`` (An array of rows, each row an array of columns)
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- This is present only when the ``result_type`` is "TuplesOk"
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.. note::
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The first row in the ``result`` (when present) will be the names of the columns.
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Some examples
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^^^^^^^^^^^^^
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An SQL query returning results.
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.. code-block:: http
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POST /v2/query HTTP/1.1
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Content-Type: application/json
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X-Hasura-Role: admin
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{
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"type": "run_sql",
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"args": {
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"source": "default",
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"sql": "select user_id, first_name from author limit 2;"
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}
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}
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.. code-block:: http
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HTTP/1.1 200 OK
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Content-Type: application/json
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{
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"result_type": "TuplesOk",
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"result": [
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[
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"user_id",
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"first_name"
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],
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[
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"1",
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"andre"
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],
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[
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"2",
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"angela"
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]
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]
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}
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An SQL query to create a table:
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.. code-block:: http
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POST /v2/query HTTP/1.1
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Content-Type: application/json
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X-Hasura-Role: admin
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{
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"type":"run_sql",
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"args": {
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"source": "default",
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"sql": "create table item ( id serial, name text, category text, primary key (id))",
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"check_metadata_consistency": false
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}
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}
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.. code-block:: http
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HTTP/1.1 200 OK
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Content-Type: application/json
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{
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"result_type": "CommandOk",
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"result": null
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}
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