Expression handling in `VortexSource` isn't consistent, and might cause runtime errors or other issues.

[AdamGS]

The default behavior in can_be_pushed_down_impl treats CastExpr as supported only by the overall shape of the child, but doesn't validate its actual children.

For example WHERE CAST(a % 2 AS BIGINT) = 0 will be pushed down, but we currently can't handle %.

This is a symptom of a bigger drift between the different checks, conversions and operations like expression splitting.

[haohuaijin]

I recently encounter this issue through the ListingTable: DataFusion pushes CAST(Utf8 AS Int64) > 0 into Vortex, which then fails at runtime with No CastReduce to cast constant array from utf8 to i64?.

And ListingTable currently provides no way to inject a custom ExpressionConvertor to reject the unsupported pushdown.

[AdamGS]

The way in that case is passing a convertor through the underlying VortexSource, depending on your setup.

[haohuaijin]

Thanks, but for users who use ListingTable to search vortex files, configuring VortexSource directly isn't straightforward because ListingTable creates sources through VortexFormat. I opened #9185 to pass a custom ExpressionConvertor through VortexFormat/VortexFormatFactory.

And publicly export ProcessedProjection ( because The ExpressionConvertor trait was already public, but split_projection returns ProcessedProjection, which was not publicly nameable — so the trait could not actually be implemented outside the crate).