Meltano

What is the difference between <https://github.com/meltano/sdk/blob/6708cb995c68ab6f74d4874dfc8f978c3b054ceb/singer_sdk/helpers/capabilities.py#L316|schema-flattening> and <https://github.com/meltano/sdk/blob/6708cb995c68ab6f74d4874dfc8f978c3b054ceb/singer_sdk/helpers/capabilities.py#L369|record-flattening> capabilities? Looking at the SDK code, it seems `schema-flattening` controls the <https://github.com/meltano/sdk/blob/6708cb995c68ab6f74d4874dfc8f978c3b054ceb/singer_sdk/plugin_base.py#L459-L460|application of flattening config>, <https://github.com/meltano/sdk/blob/6708cb995c68ab6f74d4874dfc8f978c3b054ceb/singer_sdk/mapper.py#L91-L92|schema flattening> and <https://github.com/meltano/sdk/blob/6708cb995c68ab6f74d4874dfc8f978c3b054ceb/singer_sdk/mapper.py#L146-L161|record flattening> (i.e. does more than the capability name implies). `record-flattening` does not seem to be respected. `schema-flattening` is also missing from the <https://sdk.meltano.com/en/v0.40.0/capabilities.html#built-in-base-capabilities|SDK docs>.

&gt; What is the difference between <https://github.com/meltano/sdk/blob/6708cb995c68ab6f74d4874dfc8f978c3b054ceb/singer_sdk/helpers/capabilities.py#L316|schema-flattening> and <https://github.com/meltano/sdk/blob/6708cb995c68ab6f74d4874dfc8f978c3b054ceb/singer_sdk/helpers/capabilities.py#L369|record-flattening> capabilities?
Hmm. This went under my radar :grimacing:. It seems they were added at different points:
• `record-flattening`: <https://github.com/meltano/sdk/commit/fd95f124ccdaafc6e190b31894c91b8adaf1d01b>
• `schema-flattening`: <https://github.com/meltano/sdk/commit/010b41eb80a00cd06251e5976e05d666887982f3>
I forgot the rationale, if there was any, for unfolding them like that. I see AJ titled the feature `Schema Flattening Applications` when he implemented it and MeltanoHub uses `schema-flattening`.

&gt; `record-flattening` does not seem to be respected
can you expand on what you mean by this?

&gt; `schema-flattening` is also missing from the <https://sdk.meltano.com/en/v0.40.0/capabilities.html#built-in-base-capabilities|SDK docs>.
We can add it after we clarify this mess :sweat_smile:

image.png

&gt; can you expand on what you mean by this?
`record-flattening` is a defined target capability, but I can't see where it is used - if at all.

Feels like the capability (in an ideal world) should just be `flattening` since the combination of `schema-flattening` capability and flattening config operate on both schema and records.

I agree. And the behavior is the same in both taps and targets.

<https://github.com/meltano/sdk/pull/2666>