alamb commented on code in PR #7680:
URL: https://github.com/apache/arrow-datafusion/pull/7680#discussion_r1340522395
##########
docs/source/library-user-guide/custom-table-providers.md:
##########
@@ -121,6 +121,22 @@ impl TableProvider for CustomDataSource {
With this, and the implementation of the omitted methods, we can now use the
`CustomDataSource` as a `TableProvider` in DataFusion.
+##### Additional `TableProvider` Methods
+
+`scan` has no default implementation, so it needed to be written. There are
other methods on the `TableProvider` that have default implementations, but can
be overridden if needed to provide additional functionality.
+
+###### `supports_filters_pushdown`
+
+The `supports_filters_pushdown` method can be overridden to indicate which
filter expressions support being pushed down to the data source and within that
the specificity of the pushdown.
+
+This returns a `Vec` of `TableProviderFilterPushDown` enums where each enum
represents a filter that can be pushed down. The `TableProviderFilterPushDown`
enum has three variants:
+
+- `TableProviderFilterPushDown::Unsupported` - the filter cannot be pushed down
+- `TableProviderFilterPushDown::Exact` - the filter can be pushed down and the
data source can guarantee that the filter will be applied exactly as specified
+- `TableProviderFilterPushDown::Inexact` - the filter can be pushed down, but
the data source cannot guarantee that the filter will be applied exactly as
specified
Review Comment:
```suggestion
- `TableProviderFilterPushDown::Exact` - the filter can be pushed down and
the data source can guarantee that the filter will be applied completely to all
rows. This is the highest performance option.
- `TableProviderFilterPushDown::Inexact` - the filter can be pushed down,
but the data source cannot guarantee that the filter will be applied to all
rows. DataFusion will apply `Inexact` filters again after the scan to ensure
correctness.
```
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