advancedxy commented on PR #8579:
URL: https://github.com/apache/iceberg/pull/8579#issuecomment-1899645844
> First of all, we should evaluate other hash functions apart from Murmur3.
Parquet, for instance, uses xxHash that is supposed to be much faster
> Second, Parquet avoids the modulo operator for performance reasons.
Both sounds great improvement to me. Apart from faster hash, I'd like to add
another possible option to explore: user defined hash function for bucket
transform while we are working `bucketV2`. From time to time, I got request
from users that is it possible to custom Iceberg's bucket partitioning
strategy, so that it has exactly the same distribution of downstream systems.
> If we merge a general change about multi-arg transforms, we can start
working on changes to the expression API while figuring out the details about
bucketV2.
I'm ok to merge multi-arg transform first. However I'm not sure how to
provide examples for single-arg transform v.s. multi-arg transform as there
will be no `bucketV2` transform for now. I am referring this part:
```markdown
|**`Partition Field`** [2]|`JSON object: {`<br /> `"source-id":
<id int>,`<br /> `"field-id": <field id int>,`<br
/> `"name": <name string>,`<br /> `"transform":
<transform JSON>`<br />`}`|`{`<br /> `"source-id": 1,`<br
/> `"field-id": 1000,`<br /> `"name": "id_bucket",`<br
/> `"transform": "bucket[16]"`<br />`}`|
|**`Partition Field with multi-arg transform`** [3]|`JSON object: {`<br
/> `"source-id": -1,`<br /> `"source-ids": <list of
ids>,`<br /> `"field-id": <field id int>,`<br /> `"name":
<name string>,`<br /> `"transform": <transform JSON>`<br
/>`}`|`{`<br /> `"source-id": -1,`<br /> `"source-ids":
[1,2],`<br /> `"field-id": 1000,`<br /> `"name":
"id_type_bucket",`<br /> `"transform": "bucketV2[16]"`<br />`}`|
```
@szehon-ho @aokolnychyi do you have any suggestions?
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