[
https://issues.apache.org/jira/browse/TAJO-1415?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14491503#comment-14491503
]
ASF GitHub Bot commented on TAJO-1415:
--------------------------------------
Github user jihoonson commented on a diff in the pull request:
https://github.com/apache/tajo/pull/454#discussion_r28204090
--- Diff:
tajo-core/src/main/java/org/apache/tajo/engine/parser/SQLAnalyzer.java ---
@@ -491,14 +506,16 @@ public WindowSpec
buildWindowSpec(SQLParser.Window_specificationContext ctx) {
WindowFrameStartBoundType boundType = null;
if (checkIfExist(context.UNBOUNDED())) {
boundType = WindowFrameStartBoundType.UNBOUNDED_PRECEDING;
- } else if (checkIfExist(context.unsigned_value_specification())) {
+ } else if (checkIfExist(context.PRECEDING())) {
boundType = WindowFrameStartBoundType.PRECEDING;
+ } else if (checkIfExist(context.FOLLOWING())) {
+ boundType = WindowFrameStartBoundType.FOLLOWING;
} else {
boundType = WindowFrameStartBoundType.CURRENT_ROW;
--- End diff --
In pgsql, the default start bound is ```CURRENT_ROW```. Please see the
following quote.
```
The default framing option is RANGE UNBOUNDED PRECEDING, which is the same
as RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW.
```
> Window frame support
> --------------------
>
> Key: TAJO-1415
> URL: https://issues.apache.org/jira/browse/TAJO-1415
> Project: Tajo
> Issue Type: Sub-task
> Components: distributed query plan, parser, physical operator,
> planner/optimizer
> Reporter: Keuntae Park
> Assignee: Keuntae Park
> Fix For: window function
>
>
> We can define frame clause in window definition like
> {code}
> [ RANGE | ROWS ] frame_start
> [ RANGE | ROWS ] BETWEEN frame_start AND frame_end
> {code}
> , where frame_start and frame_end can be one of
> {code}
> UNBOUNDED PRECEDING
> value PRECEDING
> CURRENT ROW
> value FOLLOWING
> UNBOUNDED FOLLOWING
> {code}
> According to the window functions description of
> PostgreSQL(http://www.postgresql.org/docs/9.4/static/functions-window.html),
> there are two types of window functions based on window frame support.
> 1) row_number, rank, dense_rank, percent_rank, cume_dist, tile, lag and lead:
> these functions only work within window partition, which means window frame
> has no effect on these functions.
> 2) first_value, last_value, nth_value, and aggregation function as as window
> function: these functions should work with rows within window frame.
> Currently, Tajo parser recognize the window frame grammar but windowAggExec
> does not use that information.
> It works as if window frame is set as "RANGE BETWEEN UNBOUND PROCEEDING AND
> UNBOUNDED FOLLOWING", which is different from the default window frame
> setting of most DBMSs "RANGE BETWEEN UNBOUND PROCEEDING AND CURRENT ROW".
> Following should be done:
> 1) Applying correct default window frame for first_value, last_value,
> nth_value, and aggregation functions .
> 2) Supporting various window frame expressions.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
