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https://issues.apache.org/jira/browse/PHOENIX-5998?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17219828#comment-17219828
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ASF GitHub Bot commented on PHOENIX-5998:
-----------------------------------------
gokceni commented on a change in pull request #936:
URL: https://github.com/apache/phoenix/pull/936#discussion_r511027115
##########
File path:
phoenix-core/src/main/java/org/apache/phoenix/iterate/UngroupedAggregatingResultIterator.java
##########
@@ -36,19 +37,33 @@ public UngroupedAggregatingResultIterator(
PeekingResultIterator resultIterator,
@Override
public Tuple next() throws SQLException {
- Tuple result = super.next();
+ byte[] value;
+ Tuple result = resultIterator.next();
+ // We should reset ClientAggregators here in case they are being
reused in a new ResultIterator.
+ aggregators.reset(aggregators.getAggregators());
// Ensure ungrouped aggregregation always returns a row, even if the
underlying iterator doesn't.
- if (result == null && !hasRows) {
- // We should reset ClientAggregators here in case they are being
reused in a new ResultIterator.
- aggregators.reset(aggregators.getAggregators());
- byte[] value = aggregators.toBytes(aggregators.getAggregators());
- result = new SingleKeyValueTuple(
- KeyValueUtil.newKeyValue(UNGROUPED_AGG_ROW_KEY,
- SINGLE_COLUMN_FAMILY,
- SINGLE_COLUMN,
- AGG_TIMESTAMP,
- value));
+ if (result == null) {
+ if (hasRows) {
+ return null;
Review comment:
This doesn't match with the above comment of always returning rows.
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> Paged server side ungrouped aggregate operations
> -------------------------------------------------
>
> Key: PHOENIX-5998
> URL: https://issues.apache.org/jira/browse/PHOENIX-5998
> Project: Phoenix
> Issue Type: Improvement
> Reporter: Kadir OZDEMIR
> Assignee: Kadir OZDEMIR
> Priority: Major
> Fix For: 4.x
>
> Attachments: PHOENIX-5998.4.x.001.patch, PHOENIX-5998.4.x.002.patch
>
>
> Phoenix provides the option of performing upsert select and delete query
> operations on the client or server side. This is decided by the Phoenix
> optimizer based on configuration parameters. For the server side option, the
> table operation (upsert select/delete query) is parallelized such that
> multiple table regions are scanned and the mutations derived from these scans
> can also be executed in parallel on the server side. However, currently there
> is no paging capability and the server side operation can take long enough
> lead to HBase client timeouts. When this happens, Phoenix can return failure
> to its applications and the rest of the parallel scans and mutations on the
> server side can still continue since Phoenix has no mechanism in place to
> stop these operations before returning failure to applications. This can
> create unexpected race conditions between these left-over operations and the
> new operations issued by applications. Putting a limit on the number of rows
> to be processed within a single RPC call (i.e., the next operation on the
> scanner) on the server side using a Phoenix level paging is highly desirable
> and a required step to prevent the possible race conditions. This paging
> mechanism has been already implemented for index rebuild and verification
> operations and proven to be effective to prevent timeouts. This paging can be
> implemented for all server side operations including aggregates, upsert
> selects, delete queries and so on.
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