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https://issues.apache.org/jira/browse/TAJO-1415?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14502398#comment-14502398
]
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_r28665661
--- Diff:
tajo-core/src/main/java/org/apache/tajo/engine/planner/physical/WindowAggExec.java
---
@@ -347,6 +350,372 @@ private void finalizeWindow() {
}
}
+
+ private void evaluateNonframableWindowFunction(int functionIndex) {
+ for (int i = 0; i < accumulatedInTuples.size(); i++) {
+ Tuple inTuple = accumulatedInTuples.get(i);
+ Tuple outTuple = evaluatedTuples.get(i);
+
+ functions[functionIndex].merge(contexts[functionIndex], inTuple);
+
+ if (windowFuncFlags[functionIndex]) {
+ Datum result =
functions[functionIndex].terminate(contexts[functionIndex]);
+ outTuple.put(nonFunctionColumnNum + functionIndex, result);
+ }
+ }
+
+ if (aggFuncFlags[functionIndex]) {
+ for (int i = 0; i < evaluatedTuples.size(); i++) {
+ Datum result =
functions[functionIndex].terminate(contexts[functionIndex]);
+ Tuple outTuple = evaluatedTuples.get(i);
+ outTuple.put(nonFunctionColumnNum + functionIndex, result);
+ }
+ }
+ }
+
+ private void evaluateFramableWindowFunction(int functionIndex,
LogicalWindowSpec.LogicalWindowFrame windowFrame,
+ BaseTupleComparator comp) {
+ LogicalWindowSpec.LogicalWindowFrame.WindowFrameType windowFrameType =
windowFrame.getFrameType();
+ WindowSpec.WindowFrameUnit windowFrameUnit =
windowFrame.getFrameUnit();
+ int windowFrameStartOffset = windowFrame.getStartBound().getNumber();
+ int windowFrameEndOffset = windowFrame.getEndBound().getNumber();
+
+ String funcName = functions[functionIndex].getName();
+ int sameStartRange = 0; int sameEndRange = 0;
+ int frameStart = 0, frameEnd = accumulatedInTuples.size() - 1;
+ int actualStart = 0;
+
+ for (int i = 0; i < accumulatedInTuples.size(); i++) {
+ switch(windowFrameType) {
+ case TO_CURRENT_ROW:
+ frameEnd = i + windowFrameEndOffset; break;
+ case FROM_CURRENT_ROW:
+ frameStart = i + windowFrameStartOffset; break;
+ case SLIDING_WINDOW:
+ frameStart = i + windowFrameStartOffset;
+ frameEnd = i + windowFrameEndOffset;
+ break;
+ }
+
+ // RANGE window frame SHOULD include all the rows that has the same
order by value with the current row
+ // if comp == null, there is no order by and window frame is set
as the entire partition
+ if (comp != null && windowFrameUnit ==
WindowSpec.WindowFrameUnit.RANGE) {
+ // move frame end point to the last row of the same order by value
+ if (sameEndRange == 0) {
+ sameEndRange = numOfTuplesWithTheSameKeyValue(frameEnd, comp,
true);
+ }
+ sameEndRange --;
+ frameEnd += sameEndRange;
+
+ // move frame start point to the first row of the same order by
value
+ if (sameStartRange == 0) {
+ sameStartRange = numOfTuplesWithTheSameKeyValue(frameStart,
comp, true);
+ actualStart = frameStart;
+ }
+ sameStartRange --;
+ frameStart = actualStart;
+ }
+ // As the number of built-in window functions that support window
frame is small,
+ // special treatment for each function seems to be reasonable
+ Tuple inTuple = getFunctionSpecificInput(funcName, frameStart,
frameEnd);
+ Datum result = NullDatum.get();
+
+ if (inTuple != null) {
+ functions[functionIndex].merge(contexts[functionIndex], inTuple);
+ result =
functions[functionIndex].terminate(contexts[functionIndex]);
+ }
+ Tuple outTuple = evaluatedTuples.get(i);
+ outTuple.put(nonFunctionColumnNum + functionIndex, result);
+ }
+ }
+
+ // it returns the number of Tuples with the same order by key value
+ // if only one Tuple for the given order by key exists, it returns 1
+ private int numOfTuplesWithTheSameKeyValue(int startOffset,
BaseTupleComparator comp, boolean isForward) {
+ int numberOfTuples = 0;
+
+ Tuple inTuple = accumulatedInTuples.get(startOffset);
+ if (isForward) {
+ do {
+ numberOfTuples++;
+ startOffset++;
+ } while (startOffset < accumulatedInTuples.size() &&
comp.compare(accumulatedInTuples.get(startOffset), inTuple) == 0);
+ } else { // backward direction
+ do {
+ numberOfTuples++;
+ startOffset--;
+ } while (startOffset >= 0 &&
comp.compare(accumulatedInTuples.get(startOffset), inTuple) == 0);
+ }
+
+ return numberOfTuples;
+ }
+
+ private Tuple getFunctionSpecificInput(String funcName, int dataStart,
int dataEnd) {
--- End diff --
Ok. I got your point.
If so, would you please add some comments for the special functions
(first_value, last_value, nth_value) to reduce confusion?
> 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.
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