openinx commented on issue #2049:
URL: https://github.com/apache/iceberg/issues/2049#issuecomment-756535921
@simonsssu It's an optimization for accessing nested field. For example,
we have the schema:
```
root
|-- a: struct (nullable = false)
| |-- b: struct (nullable = false)
| | -- c: string (containsNull = false)
```
We could just use the `Position3Accessor` to access the nested field `c`
(Because it just access the nested field straightforward : `row.get(p0,
StructLike.class).get(p1, StructLike.class).get(p2, javaClass);` ).
Of course, it won't break the correctness if we remove that optimization,
then we will use the `WrappedPositionAccessor` to access field `c` recursively,
that's a more complex stack trace which may consume more resources.
But I think it's good to keep the optimization because the nested fields
with depth=1 or 2 or 3 are the fields that will be accessed with the highest
frequency.
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