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https://issues.apache.org/jira/browse/DRILL-24?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13580529#comment-13580529
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Timothy Chen commented on DRILL-24:
-----------------------------------
How does the parser decide what order to swap? I would assume it defaults to
left join when the left side is significantly larger, but I'm sure it won't
cover all cases.
Do you think we should leave right join in there for now?
> Implement Join Reference Operator
> ---------------------------------
>
> Key: DRILL-24
> URL: https://issues.apache.org/jira/browse/DRILL-24
> Project: Apache Drill
> Issue Type: New Feature
> Reporter: Timothy Chen
> Assignee: Timothy Chen
> Labels: logical
> Attachments: join.patch
>
>
> Join (M)
> Joins two inputs based on one or more join conditions. The output of this
> operator is the combination of the two inputs. This is done by providing a
> combination record of each set of input records that matches all provided
> join conditions. In the case that no conditions are provided, a cartesian
> join is generated. The combination record is a single record that contains a
> merged map of values from both provided input records. For example, if the
> left record is {donuts: [data]} and the right is {purchases: [data]}, the
> combination record would be {donuts: [data], purchases: [data]}. Join also
> requires a condition type variable which. This describes what happens when a
> record doesn’t match the join conditions. Inner means only records that
> match the join conditions should be included. Outer means if a record is
> Avaiable relationship types ‘Reltypes’ include: >, >=, <=, <, !=, ==
> { @id†: <opref>, op: “join”,
> left: <input>,
> right: <input>,
> type: <inner|outer|right|left>,
> conditions*: [
> {relationship: <reltype>, left: <expr>, right: <expr>}, ...
> ]
> }
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