alamb commented on code in PR #20193:
URL: https://github.com/apache/datafusion/pull/20193#discussion_r2775086602
##########
datafusion/datasource/src/file_scan_config.rs:
##########
@@ -793,37 +793,27 @@ impl DataSource for FileScanConfig {
config: &ConfigOptions,
) -> Result<FilterPushdownPropagation<Arc<dyn DataSource>>> {
// Remap filter Column indices to match the table schema (file +
partition columns).
- // This is necessary because filters may have been created against a
different schema
- // (e.g., after projection pushdown) and need to be remapped to the
table schema
- // before being passed to the file source and ultimately serialized.
- // For example, the filter being pushed down is `c1_c2 > 5` and it was
created
- // against the output schema of the this `DataSource` which has
projection `c1 + c2 as c1_c2`.
- // Thus we need to rewrite the filter back to `c1 + c2 > 5` before
passing it to the file source.
+ // This is necessary because filters refer to the output schema of
this `DataSource`
Review Comment:
Clarified that the "different schema" is the "table schema"
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