Upsert: Don't produce empty snapshots #1810
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Yikes! This makes sure to only produce a snapshot when there is anything to update or add.
kevinjqliu
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Mar 19, 2025
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| tx.overwrite(rows_to_update, overwrite_filter=overwrite_mask_predicate) | ||
| tx.overwrite(rows_to_update, overwrite_filter=overwrite_mask_predicate) |
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should we enforce not producing empty snapshots lower in the stack, in the write functions themselves (overwrite/append)?
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Yes, that's a great suggestion. I was also looking into that, but there are two caveats:
- Before computing all the manifests, we don't know if they are empty. The delete manifests are lazily computed, so making sure that we short-circuit earlier in the process, makes sure that we don't do all the work.
- There is also a behavioral aspect around it, for example, when you do
tbl.append(df)wheredfis empty, ortbl.delete('x = 10'), you may still want to produce a snapshot to indicate that something happened. My opinion is that it should result in a no-op, but Java creates a snapshot:
I believe @sungwy and I had a similar discussion.
Fokko
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# Rationale for this change
Yikes! This makes sure to only produce a snapshot when there is anything
to update or append.
# Are these changes tested?
Yes, by checking the snapshots that are being produced.
# Are there any user-facing changes?
Smaller metadata and faster commits when there is nothing to
append/update :)
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gabeiglio
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Aug 13, 2025
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# Rationale for this change
Yikes! This makes sure to only produce a snapshot when there is anything
to update or append.
# Are these changes tested?
Yes, by checking the snapshots that are being produced.
# Are there any user-facing changes?
Smaller metadata and faster commits when there is nothing to
append/update :)
<!-- In the case of user-facing changes, please add the changelog label.
-->
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Rationale for this change
Yikes! This makes sure to only produce a snapshot when there is anything to update or append.
Are these changes tested?
Yes, by checking the snapshots that are being produced.
Are there any user-facing changes?
Smaller metadata and faster commits when there is nothing to append/update :)