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https://issues.apache.org/jira/browse/ASTERIXDB-1407?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15253479#comment-15253479
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Yingyi Bu commented on ASTERIXDB-1407:
--------------------------------------
>> 2. The data properties of the probe branch can still be maintained after a
>> nested loop join but a broadcast will clear all data properties of a branch.
It turns out that this is not true because of the I/O optimization we did for
block nested loop join:
{noformat}
\\ iterate over the build (inner) branch frames
while (runFileReader.nextFrame(innerBuffer)) {
\\ iterate over the probe (outer) branch frames
for (int i = 0; i < outerBufferMngr.getNumFrames(); i++) {
blockJoin(outerBufferMngr.getFrame(i, tempInfo),
innerBuffer.getBuffer(), writer);
}
}
{noformat}
> Let the build branch instead of the probe branch to broadcast for NLJ
> ---------------------------------------------------------------------
>
> Key: ASTERIXDB-1407
> URL: https://issues.apache.org/jira/browse/ASTERIXDB-1407
> Project: Apache AsterixDB
> Issue Type: Improvement
> Reporter: Yingyi Bu
> Assignee: Yingyi Bu
>
> There are two motivations for that change:
> 1. Usually the build branch is smaller;
> 2. The data properties of the probe branch can still be maintained after a
> nested loop join but a broadcast will clear all data properties of a branch.
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