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128 lines
5.4 KiB
ReStructuredText
128 lines
5.4 KiB
ReStructuredText
.. meta::
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:description: Troubleshoot Hasura GraphQL engine errors
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:keywords: hasura, docs, error, troubleshooting
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Troubleshooting Hasura GraphQL engine errors
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============================================
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.. contents:: Table of contents
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:backlinks: none
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:depth: 1
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:local:
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The Hasura GraphQL engine may not work as expected and will throw unexpected errors if the tables/views tracked by
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the GraphQL engine are altered using ``psql`` or any other PostgreSQL client.
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The Hasura GraphQL engine creates and maintains an **internal state** based on the database it is configured to use.
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This internal state will comprise information about the tables/views, relationships and access control rules
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defined on them using the Hasura GraphQL engine. See :doc:`Hasura GraphQL metadata schema <../how-it-works/metadata-schema>`
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for information on how this internal state is maintained. It is highly recommended doing any modifications to the
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database schema only through the Hasura console to avoid corrupting the GraphQL engine's state.
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Following are the list of error messages returned by the GraphQL engine when it encounters an inconsistent state:
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Error: no such table/view exists in postgres
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--------------------------------------------
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This error is thrown when a table/view tracked by the Hasura GraphQL engine is not available in the
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database.
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For example, you will encounter the above error if you have:
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- Created/tracked a table called ``author`` from console.
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- Opened ``psql`` or ``adminer`` or any other PostgreSQL client and deleted ``author`` table.
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- Restarted GraphQL engine.
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In this example, the GraphQL engine expects the table ``author`` to be available in the database to
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function properly but it can't find it.
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Solution
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^^^^^^^^
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- Connect to the database and switch to ``hdb_catalog`` schema.
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- Delete the row from ``hdb_table`` table where the column ``table_name`` has the value ``author``.
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- Restart the GraphQL engine to verify.
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Error: no foreign constraint exists on the given column
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-------------------------------------------------------
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The Hasura GraphQL engine validates all the relationships (created using foreign key/manually) before it starts serving.
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When it encounters a relationship defined from table ``A -> B`` it looks for a foreign key constraint in table ``A``
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and when it can't find it, it throws the above error.
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Solution
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^^^^^^^^
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- Connect to the database and switch to ``hdb_catalog`` schema.
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- In the ``hdb_relationship`` table, find the entry for the above relationship and delete it.
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- Restart GraphQL engine to verify.
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Error: field already exists
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---------------------------
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When a relationship is created using the Hasura GraphQL engine, it creates a special field with the relationship name
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which is used while fetching nested objects using GraphQL.
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Let's say we have tables called ``article`` and ``author`` as follows:
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.. thumbnail:: ../../../img/graphql/manual/troubleshooting/author_article.jpg
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:alt: article author schema
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Using the console if you have created a relationship named ``author`` from the ``article`` table to
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the ``author`` table, the Hasura GraphQL engine will create a special field ``author`` in the ``article`` table in its
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internal state. This field will be available via the GraphQL interface.
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When this table is described using ``psql``, the ``author`` field will not be available as part of the list of fields
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returned by the describe command as it is something added by Hasura GraphQL engine. Now if a new column is created
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with the same name, i.e. ``author``, via ``psql``, the Hasura GraphQL engine will throw the above error when restarted as it has two
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references to the ``author`` field for the ``article`` table.
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Solution
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^^^^^^^^
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- Delete the problematic column from the table.
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- Restart GraphQL engine to verify.
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OR
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- Connect to the database and switch to the ``hdb_catalog`` schema.
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- In the ``hdb_relationship`` table, find the entry for the above relationship and delete it.
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- Restart the GraphQL engine to verify.
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Error: column does not exist
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----------------------------
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This error is thrown when a column of a table used by the Hasura GraphQL engine is not available in the
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database.
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For example, you will encounter the above error if you have:
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- Created a permission rule using a column in a check.
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- Opened ``psql`` or ``adminer`` or any other PostgreSQL client and deleted the column from the table.
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- Restarted GraphQL engine.
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In this example, the GraphQL engine expects the column to be available in the table to
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function properly but it can't find it.
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Solution
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^^^^^^^^
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- Connect to the database and switch to the ``hdb_catalog`` schema.
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- Delete the row from the ``hdb_permission`` table where the column ``table_name`` has the same value as the table
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mentioned in the error and the column ``perm_def`` involves the missing column.
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- Restart the GraphQL engine to verify.
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Error: cannot continue due to new inconsistent metadata
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-------------------------------------------------------
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Some updates to the Hasura GraphQL engine may have :ref:`Hasura catalogue <hasura_metadata_schema>` version bumps. The GraphQL engine server
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automatically migrates the catalogue to the latest version on startup. This migration may fail if the previous metadata state is inconsistent.
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Solution
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^^^^^^^^
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- Start the older version of the GraphQL engine.
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- Open the Hasura console to find the inconsistencies.
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- Clear the inconsistencies.
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- Start the newer version.
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