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Add a working, more complete example of using a catalog (docs) #1427

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Add a working, more complete example of using a catalog
toppyy Mar 13, 2026
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the default schema is 'public', not 'default'
toppyy Mar 14, 2026
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22 changes: 15 additions & 7 deletions docs/source/user-guide/data-sources.rst
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Expand Up @@ -224,25 +224,33 @@ A common technique for organizing tables is using a three level hierarchical app
supports this form of organizing using the :py:class:`~datafusion.catalog.Catalog`,
:py:class:`~datafusion.catalog.Schema`, and :py:class:`~datafusion.catalog.Table`. By default,
a :py:class:`~datafusion.context.SessionContext` comes with a single Catalog and a single Schema
with the names ``datafusion`` and ``default``, respectively.
with the names ``datafusion`` and ``public``, respectively.

The default implementation uses an in-memory approach to the catalog and schema. We have support
for adding additional in-memory catalogs and schemas. This can be done like in the following
for adding additional in-memory catalogs and schemas. You can access tables registered in a schema
either through the Dataframe API or vial sql commands. This can be done like in the following
example:

.. code-block:: python

from datafusion.catalog import Catalog, Schema
from datafusion import SessionContext

ctx = SessionContext()

my_catalog = Catalog.memory_catalog()
my_schema = Schema.memory_schema()
my_catalog = Catalog.memory_catalog()
my_schema = Schema.memory_schema()

my_catalog.register_schema("my_schema_name", my_schema)
ctx.register_catalog_provider("my_catalog_name", my_catalog)

df = ctx.read_csv("pokemon.csv")

my_schema.register_table('pokemon',df)

ctx.register_catalog("my_catalog_name", my_catalog)
pokemon = ctx.sql("SELECT * FROM my_catalog_name.my_schema_name.pokemon")

You could then register tables in ``my_schema`` and access them either through the DataFrame
API or via sql commands such as ``"SELECT * from my_catalog_name.my_schema_name.my_table"``.
pokemon.show()

User Defined Catalog and Schema
-------------------------------
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