[GitHub] [arrow] sunchao commented on a change in pull request #9064: ARROW-11074: [Rust][DataFusion] Implement predicate push-down for parquet tables

[GitBox <gi...@apache.org>]

sunchao commented on a change in pull request #9064:
URL: https://github.com/apache/arrow/pull/9064#discussion_r551558307



##########
File path: rust/datafusion/src/datasource/parquet.rs
##########
@@ -62,17 +64,37 @@ impl TableProvider for ParquetTable {
         self.schema.clone()
     }
 
+    fn supports_filter_pushdown(
+        &self,
+        _filter: &Expr,
+    ) -> Result<TableProviderFilterPushDown> {
+        Ok(TableProviderFilterPushDown::Inexact)
+    }
+
     /// Scan the file(s), using the provided projection, and return one BatchIterator per
     /// partition.
     fn scan(
         &self,
         projection: &Option<Vec<usize>>,
         batch_size: usize,
-        _filters: &[Expr],
+        filters: &[Expr],

Review comment:
       Ideally, I feel we should have a proper filter API defined in data fusion which can be shared among various data sources. On the other hand, the actual filtering logic should be implemented by different data sources / formats, probably via converting the data fusion's filter API to the corresponding ones from the latter. 
   
   But this is a very good start and we can probably do them as follow ups (if we don't care much for API changes).

##########
File path: rust/parquet/src/file/serialized_reader.rs
##########
@@ -137,6 +137,22 @@ impl<R: 'static + ChunkReader> SerializedFileReader<R> {
             metadata,
         })
     }
+
+    pub fn filter_row_groups(

Review comment:
       Yeah I think we can either move this to the application layer (i.e., data fusion), or expose it as a util function from `footer.rs`.




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