> ## Documentation Index
> Fetch the complete documentation index at: https://arizeai-433a7140.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Filter Spans to Export

Sometimes while instrumenting your application, you may want to filter out or modify certain spans from being sent to Phoenix. For example, you may want to filter out spans that are that contain sensitive information or contain redundant information.

To do this, you can use a custom `SpanProcessor` and attach it to the OpenTelemetry `TracerProvider`.

<Tabs>
  <Tab title="Python" icon="python">
    ```python theme={null}
    from phoenix.otel import register
    from phoenix.otel import BatchSpanProcessor
    from opentelemetry.context import Context
    from opentelemetry.sdk.trace import ReadableSpan, Span


    class FilteringSpanProcessor(BatchSpanProcessor):
        def _filter_condition(self, span: Span) -> bool:
            # returns True if the span should be filtered out
            return span.name == "secret_span"

        def on_start(self, span: Span, parent_context: Context) -> None:
            if self._filter_condition(span):
                return
            super().on_start(span, parent_context)

        def on_end(self, span: ReadableSpan) -> None:
            if self._filter_condition(span):
                logger.info("Filtering span: %s", span.name)
                return
            super().on_end(span)


    tracer_provider = register()
    tracer_provider.add_span_processor(
        FilteringSpanProcessor(
            endpoint="http://localhost:6006/v1/traces",
            protocol="http/protobuf",
        )
    )
    ```

    In this example, we're filtering out any spans that have the name "secret\_span" by bypassing the `on_start` and `on_end` hooks of the inherited `BatchSpanProcessor`.

    Notice that this logic can be extended to modify a span and redact sensitive information if preserving the span is preferred.
  </Tab>
</Tabs>