lidavidm commented on code in PR #41823:
URL: https://github.com/apache/arrow/pull/41823#discussion_r1618185457
##########
docs/source/format/CanonicalExtensions.rst:
##########
@@ -283,6 +283,61 @@ UUID
A specific UUID version is not required or guaranteed. This extension
represents
UUIDs as FixedSizeBinary(16) with big-endian notation and does not
interpret the bytes in any way.
+Other
+=====
+
+Other represents a type or array that one Arrow-based system received from an
+external (likely non-Arrow) system, but cannot interpret itself. In this
+case, the Other type explicitly communicates the name and presence of a field
+to downstream clients.
+
+For example:
+
+* A Flight SQL service may support connecting external databases. In this
+ case, its catalog (``GetTables`` etc.) should reflect the names and types of
+ tables in external databases. These tables may support types it does not
+ recognize. Instead of erroring or silently dropping columns from the
+ catalog, it can use the Other[Null] type to report that a column exists with
+ a particular name and type name in the external database; the Other type
+ lets clients know that the column is not supported, but still exists.
+
+* The ADBC PostgreSQL driver, because of how the PostgreSQL wire protocol
+ works, may get bytes for a field whose type it does not recognize (say, a
+ geospatial type). It can still return the bytes to the application which
+ may be able to parse the data itself. In that case, it can use the
+ Other[binary] type to return the column data. The Other type differentiates
+ the column from actual binary columns.
+
+Extension parameters:
+
+* Extension name: ``arrow.other``.
+
+* The storage type of this extension is any type. If there is no underlying
+ data, the storage type should be NA. If there is data (because the system
+ got bytes or some other data it does not know how to interpret), the storage
+ type should preferably be binary or fixed-size binary, but may be any type.
+
+* Extension type parameters:
+
+ * **type_name** = the name of the unknown type in the external system.
+ * **vendor_name** = the name of the external system.
+
+* Description of the serialization:
+
+ A valid JSON object containing the parameters as fields. In the future,
+ additional fields may be added, but all fields current and future are never
+ required to interpret the array.
+
+ For example:
+
+ - The PostgreSQL ``polygon`` type may be represented as Other[binary] with
+ metadata ``{"type_name": "polygon", "vendor_name": "PostgreSQL"}``.
+ - The PostgreSQL ``point`` type may be represented as
+ Other[fixed_size_binary[16]] with metadata
+ ``{"type_name": "point", "vendor_name": "PostgreSQL"}``.
Review Comment:
Updated the example.
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: github-unsubscr...@arrow.apache.org
For queries about this service, please contact Infrastructure at:
us...@infra.apache.org
