[ARROW-9503] [Rust] Comparison sliced arrays is wrong

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.0.0
• Component/s: Rust
• Labels: pull-request-available
• External issue URL: https://github.com/apache/arrow/issues/25571
• Assignee: Paddy Horan
• Reporter: Ritchie
• Created: 16/Jul/20 06:53
• Updated: 11/Jan/23 08:07
• Resolved: 17/Jul/20 05:08

Description

Comparison of arrow arrays where one is sliced is dependent on the order of comparison, and doesn't always yield correct results.

The following minimal example shows the differing results.

Unable to find source-code formatter for language: rust. Available languages are: actionscript, ada, applescript, bash, c, c#, c++, cpp, css, erlang, go, groovy, haskell, html, java, javascript, js, json, lua, none, nyan, objc, perl, php, python, r, rainbow, ruby, scala, sh, sql, swift, visualbasic, xml, yaml

        use arrow::{
            datatypes::Int32Type,
            compute,
            array::{
                Array,
                PrimitiveBuilder,
                PrimitiveArray
            }
        };
        let mut builder = PrimitiveBuilder::new(10);
        for v in 0..10 {
            builder.append_value(v).unwrap()
        }
        let a: PrimitiveArray<Int32Type> = builder.finish();

        let mut builder = PrimitiveBuilder::new(10);
        for v in 5..10 {
            builder.append_value(v).unwrap()
        }
        let b: PrimitiveArray<Int32Type> = builder.finish();
        // returns Array trait
        let sliced_a = a.slice(5, 5);
        // Downcast to PrimitiveArray
        let sliced_a = sliced_a.as_any().downcast_ref().unwrap();

        println!("{:?}", a.slice(5, 5));
        println!("{:?}", b);
        println!("{:?}", compute::eq(sliced_a, &b));
        println!("{:?}", compute::eq(&b, sliced_a))

This prints:

Unable to find source-code formatter for language: text. Available languages are: actionscript, ada, applescript, bash, c, c#, c++, cpp, css, erlang, go, groovy, haskell, html, java, javascript, js, json, lua, none, nyan, objc, perl, php, python, r, rainbow, ruby, scala, sh, sql, swift, visualbasic, xml, yaml

PrimitiveArray<Int32>
[
  5,
  6,
  7,
  8,
  9,
]
PrimitiveArray<Int32>
[
  5,
  6,
  7,
  8,
  9,
]
Ok(PrimitiveArray<Boolean>
[
  false,
  false,
  false,
  false,
  false,
])
Ok(PrimitiveArray<Boolean>
[
  true,
  true,
  true,
  true,
  true,
])

I would expect both comparison arrays to evaluate to true. This same effect is also occurring with utf8arrays.

Issue Links

• links to: GitHub Pull Request #7788