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Make dictionary preservation optional in row encoding #3831

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Merged
merged 3 commits into from
Mar 10, 2023
Merged

Make dictionary preservation optional in row encoding #3831

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Make dictionary preservation optional in row encoding
tustvold Mar 9, 2023
d128b5a
Merge remote-tracking branch 'upstream/master' into optionally-preser…
tustvold Mar 9, 2023
d8f2b1e
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tustvold Mar 10, 2023
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20 changes: 19 additions & 1 deletion arrow-row/src/dictionary.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -17,7 +17,7 @@

use crate::fixed::{FixedLengthEncoding, FromSlice};
use crate::interner::{Interned, OrderPreservingInterner};
use crate::{null_sentinel, Rows};
use crate::{null_sentinel, Row, Rows};
use arrow_array::builder::*;
use arrow_array::cast::*;
use arrow_array::types::*;
Expand Down Expand Up @@ -56,6 +56,24 @@ pub fn compute_dictionary_mapping(
}
}

/// Encode dictionary values not preserving the dictionary encoding
pub fn encode_dictionary_values<K: ArrowDictionaryKeyType>(
out: &mut Rows,
column: &DictionaryArray<K>,
values: &Rows,
null: &Row<'_>,
) {
for (offset, k) in out.offsets.iter_mut().skip(1).zip(column.keys()) {
let row = match k {
Some(k) => values.row(k.as_usize()).data,
None => null.data,
};
let end_offset = *offset + row.len();
out.buffer[*offset..end_offset].copy_from_slice(row);
*offset = end_offset;
}
}

/// Dictionary types are encoded as
///
/// - single `0_u8` if null
Expand Down
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