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https://issues.apache.org/jira/browse/ARROW-9555?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Andy Grove updated ARROW-9555:
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Description:
Here is an overview of how I think we should implement support for equijoins,
at least for the initial implementation.
* Read all batches from the left-side of the join into a single
Vec<RecordBatch>
* Create a map something like HashMap<Vec<ScalarValue>, Vec<(usize,usize)>> to
map keys to batch/row indices
* Iterate over this Vec<RecordBatch> and create an entry in a hash map,
mapping the join keys to the index of the batch and row in the Vec<RecordBatch>
* For each input partition on the right-side of the join, return an output
partition that is an iterator/stream that:
** For each input row, evaluate the join keys
** Look up those join keys in the hash map
** If a match is found:
*** For each (batch, row) index create an output row which has the values from
both the left and right row and emit it
** If no match is found:
*** Do not emit a row
> Add inner (hash) join physical plan
> -----------------------------------
>
> Key: ARROW-9555
> URL: https://issues.apache.org/jira/browse/ARROW-9555
> Project: Apache Arrow
> Issue Type: Sub-task
> Components: Rust - DataFusion
> Reporter: Jorge Leitão
> Priority: Major
> Labels: pull-request-available
> Time Spent: 40m
> Remaining Estimate: 0h
>
> Here is an overview of how I think we should implement support for equijoins,
> at least for the initial implementation.
> * Read all batches from the left-side of the join into a single
> Vec<RecordBatch>
> * Create a map something like HashMap<Vec<ScalarValue>, Vec<(usize,usize)>>
> to map keys to batch/row indices
> * Iterate over this Vec<RecordBatch> and create an entry in a hash map,
> mapping the join keys to the index of the batch and row in the
> Vec<RecordBatch>
> * For each input partition on the right-side of the join, return an output
> partition that is an iterator/stream that:
> ** For each input row, evaluate the join keys
> ** Look up those join keys in the hash map
> ** If a match is found:
> *** For each (batch, row) index create an output row which has the values
> from both the left and right row and emit it
> ** If no match is found:
> *** Do not emit a row
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