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https://issues.apache.org/jira/browse/DRILL-31?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jacques Nadeau resolved DRILL-31.
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Resolution: Fixed
Awesome work! Nice tests too. Committed to master.
> Implement WindowsFrame Reference Operator
> -----------------------------------------
>
> Key: DRILL-31
> URL: https://issues.apache.org/jira/browse/DRILL-31
> Project: Apache Drill
> Issue Type: New Feature
> Reporter: Timothy Chen
> Assignee: Timothy Chen
> Labels: logical
>
> Window Frame (1)
> For each record of an incoming stream (let’s call this the target record),
> the window operator will create a segment containing the records in a sliding
> window surrounding the target record. The sliding window will include a
> specified number of records before and/or after the target record. The
> window frame operator can operate across an entire input stream or can be
> told to only allow operations within each incoming segment.
> A simple example: a window range of -2 start and 0 end is applied to a 5
> record single segment input [0,1,2,3,4]. This would result in an output of
> 12 rows (brackets describe each output segment) [0] [0,1] [0,1,2] [1,2,3]
> [2,3,4]. Each output record would have contain two additional fields:
> ref.segment which holds the current window segment and ref.position which
> will the negative, positive or zero position within the window. For the
> example data, the values to each of these would be: ref.segment:
> [0,1,1,2,2,2,3,3,3,4,4,4], ref.position: [0,-1,0,-1,0,1,-1,0,1,-1,0,1]
> A window operator can also optionally take a segment key as input. This key
> is used to restrict the windows so that they do not cross segment boundaries.
> The window operator takes as inputs a ‘start’ and an ‘end’ value. These
> values define the range of the window. The window range is defined based on
> thinking of the target record as zero, and each record after incrementing
> positively and each record before incrementing negatively. In the case that
> start or end is not defined, that portion of the range will be unbounded. In
> all cases, start must be greater than or equal to end. At least one of start
> or end must be defined.
> { @id†: <opref>, op: “windowframe”,
> input†: <input>,
> within*: <name>,
> start*: <number>,
> end*: <number>
> ref: {
> segment: <name>,
> position: <name>
> },
> }
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