tustvold commented on code in PR #2589:
URL: https://github.com/apache/arrow-rs/pull/2589#discussion_r954889181
##########
arrow/src/array/array_dictionary.rs:
##########
@@ -491,21 +490,30 @@ where
K: ArrowPrimitiveType,
V: Sync + Send,
&'a V: ArrayAccessor,
+ <&'a V as ArrayAccessor>::Item: Default,
{
type Item = <&'a V as ArrayAccessor>::Item;
fn value(&self, index: usize) -> Self::Item {
- assert!(self.dictionary.is_valid(index), "{}", index);
- let value_idx = self.dictionary.keys.value(index).to_usize().unwrap();
- // Dictionary indexes should be valid
- unsafe { self.values.value_unchecked(value_idx) }
+ assert!(
+ index < self.len(),
+ "Trying to access an element at index {} from a
TypedDictionaryArray of length {}",
+ index,
+ self.len()
+ );
+ unsafe { self.value_unchecked(index) }
}
unsafe fn value_unchecked(&self, index: usize) -> Self::Item {
let val = self.dictionary.keys.value_unchecked(index);
let value_idx = val.to_usize().unwrap();
- // Dictionary indexes should be valid
- self.values.value_unchecked(value_idx)
+
+ // As dictionary keys are only verified for non-null indexes
+ // we must check the value is within bounds
+ match value_idx < self.dictionary.len() {
Review Comment:
As pointed out by @crepererum the fact the value is in a dictionary in the
first place likely indicates that operations on it are likely to be non-trival
(i.e. it is likely a string). Therefore the cost of this bound check is likely
irrelevant, especially since because of #1918 we are doing checked conversion
to usize anyway.
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