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Helper function to get recently updated partitions #23

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huynguyent opened this issue Feb 3, 2024 · 1 comment
Open
1 of 3 tasks

Helper function to get recently updated partitions #23

huynguyent opened this issue Feb 3, 2024 · 1 comment
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@huynguyent
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Is your feature request related to a problem? Please describe.

Similar to MrPowers/mack#130 , but for non-Spark projects

For streaming systems (or batch systems that run in high frequency) that write data into delta tables, it's a common problem to have lots of small files. In many cases, it's not practical to auto compact because of various reasons, for example

  • Auto compaction is not available in Delta lake before 3.1.0
  • Auto compaction might not be well supported outside Spark

One way to solve this is to have a separate process that perform optimization regularly on these delta tables. However it's not a good idea to optimize the entire table whenever without any constraint. A few example reasons:

  • While in theory optimize is a no-op if the partitions weren't updated, it still takes some overhead per partition to determine it's a no-op. This could add up quite significantly when you have lots of partitions.
  • If the optimize operation included z-order, subsequent z-order operations won't be no-op even if the partitions weren't updated

Describe the solution you'd like
A helper function to find out which partitions have been updated between some time period, for example

def get_updated_partitions(delta_table: DeltaTable, start_time: datetime.datetime, end_time: datetime.datetime, exclude_optimize_operations: bool) -> list[dict[str, str]]

The exclude_optimize_operations flag is necessary because optimization operations themselves are also update operations. If the operations are not excluded, they might cause a feedback loop since they will keep showing up in the output.

All the information needed for this features should be available in the transaction log.

Describe alternatives you've considered
Optimizing the entire table and accept the overhead

Not sure what's a good alternative once z-order is used however

Additional context

N/A

Willingness to contribute

Would you be willing to contribute an implementation of this feature?

  • Yes. I can contribute this feature independently.
  • Yes. I would be willing to contribute this feature with guidance from the mack community.
  • No. I cannot contribute this feature at this time.
@MrPowers MrPowers assigned MrPowers and huynguyent and unassigned MrPowers Feb 4, 2024
@MrPowers
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MrPowers commented Feb 4, 2024

Thanks @huynguyent. Assigned this one to you! Looking forward to seeing what you can build!

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