Dandandan commented on code in PR #14700:
URL: https://github.com/apache/datafusion/pull/14700#discussion_r1957866816
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datafusion/functions/src/string/chr.rs:
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@@ -36,26 +36,40 @@ use datafusion_macros::user_doc;
pub fn chr(args: &[ArrayRef]) -> Result<ArrayRef> {
let integer_array = as_int64_array(&args[0])?;
- // first map is the iterator, second is for the `Option<_>`
- let result = integer_array
- .iter()
- .map(|integer: Option<i64>| {
- integer
- .map(|integer| {
- if integer == 0 {
- exec_err!("null character not permitted.")
- } else {
- match core::char::from_u32(integer as u32) {
- Some(integer) => Ok(integer.to_string()),
- None => {
- exec_err!("requested character too large for
encoding.")
- }
+ let mut builder = GenericStringBuilder::<i32>::with_capacity(
+ integer_array.len(),
+ // This assumes the maximum length of a single character is 4 bytes,
+ // which might be overly pessimistic
+ integer_array.len() * 4,
Review Comment:
Maybe it can assume 1 or 2 bytes instead? This means max 4 (or 2 when
assuming 2 bytes) allocations per array and in common cases 1-2.
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