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https://issues.apache.org/jira/browse/ARROW-2144?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16361595#comment-16361595
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ASF GitHub Bot commented on ARROW-2144:
---------------------------------------
trxcllnt commented on a change in pull request #1599: ARROW-2144: [JS] Don't
repeat dictionary lookups in DataFrame ops
URL: https://github.com/apache/arrow/pull/1599#discussion_r167719671
##########
File path: js/src/vector.ts
##########
@@ -414,6 +414,16 @@ export class DictionaryVector<T extends DataType =
DataType> extends Vector<Dict
}
public getKey(index: number) { return this.indicies.get(index); }
public getValue(key: number) { return this.dictionary.get(key); }
+ public reverseLookup(value: T): number|undefined {
+ let key = -1;
+ for (let len = this.dictionary.length; ++key < len;) {
+ if (this.dictionary.get(key) === value) {
Review comment:
@TheNeuralBit is it worthwhile to cache the dictionary lookup in a local
variable to avoid the repeated `this.dictionary` lookups?
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> [JS] Don't repeat dictionary lookups in DataFrame ops
> -----------------------------------------------------
>
> Key: ARROW-2144
> URL: https://issues.apache.org/jira/browse/ARROW-2144
> Project: Apache Arrow
> Issue Type: Improvement
> Components: JavaScript
> Reporter: Brian Hulette
> Priority: Major
> Labels: pull-request-available
>
> Currently we repeat dictionary lookups every time we bind a new record batch
> when doing an equality check in a DataFrame op
> (https://github.com/apache/arrow/blob/master/js/src/predicate.ts#L143).
> In most cases the dictionary won't be changing between record batches, so we
> should remember these reverse dictionary lookups, either permanently, or at
> least for the duration of the current operation.
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