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Posted to issues@flink.apache.org by "Fabian Hueske (JIRA)" <ji...@apache.org> on 2016/02/23 10:49:18 UTC
[jira] [Updated] (FLINK-3479) Add hash-based strategy for
CombineFunction
[ https://issues.apache.org/jira/browse/FLINK-3479?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Fabian Hueske updated FLINK-3479:
---------------------------------
Description:
This issue is similar to FLINK-3477 but adds a hash-based strategy for {{CombineFunction}} instead of {{ReduceFunction}}.
The interface of {{CombineFunction}} differs from {{ReduceFunction}} by providing an {{Iterable<T>}} instead of two {{T}} values. Hence, if the {{Iterable<T>}} provides two values, we can do the same as with a {{ReduceFunction}}.
At the moment, {{CombineFunction}} is wrapped in a {{GroupCombineFunction}} and hence executed using the {{GroupReduceCombineDriver}}.
We should add dedicated two dedicated drivers: {{CombineDriver}} and {{ChainedCombineDriver}} and two driver strategies: {{HASH_COMBINE}} and {{SORT_COMBINE}}.
If FLINK-3477 is resolved, we can reuse the hash-table.
We should also add compiler hints to `DataSet.reduceGroup()` and `Grouping.reduceGroup()` to allow users to select between a {{SORT}} and {{HASH}} based combine strategies ({{HASH}} will only be applicable to {{CombineFunction}} and not {{GroupCombineFunction}}).
was:
This issue is similar to FLINK-3477 but adds a hash-based strategy for {{CombineFunction}} instead of {{ReduceFunction}}.
The interface of {{CombineFunction}} differs from {{ReduceFunction}} by providing an {{Iterable<T>}} instead of two {{T}} values. Hence, if the {{Iterable<T>}} provides two values, we can do the same as with a {{ReduceFunction}}.
At the moment, {{CombineFunction}} is wrapped in a {{GroupCombineFunction}} and hence executed using the {{GroupReduceCombineDriver}}.
We should add dedicated two dedicated drivers: {{CombineDriver}} and {{ChainedCombineDriver}} and two driver strategies: {{HASH_COMBINE}} and {{SORT_COMBINE}}.
If FLINK-3477 is resolved, we can reuse the hash-table.
> Add hash-based strategy for CombineFunction
> -------------------------------------------
>
> Key: FLINK-3479
> URL: https://issues.apache.org/jira/browse/FLINK-3479
> Project: Flink
> Issue Type: Sub-task
> Components: Local Runtime
> Reporter: Fabian Hueske
>
> This issue is similar to FLINK-3477 but adds a hash-based strategy for {{CombineFunction}} instead of {{ReduceFunction}}.
> The interface of {{CombineFunction}} differs from {{ReduceFunction}} by providing an {{Iterable<T>}} instead of two {{T}} values. Hence, if the {{Iterable<T>}} provides two values, we can do the same as with a {{ReduceFunction}}.
> At the moment, {{CombineFunction}} is wrapped in a {{GroupCombineFunction}} and hence executed using the {{GroupReduceCombineDriver}}.
> We should add dedicated two dedicated drivers: {{CombineDriver}} and {{ChainedCombineDriver}} and two driver strategies: {{HASH_COMBINE}} and {{SORT_COMBINE}}.
> If FLINK-3477 is resolved, we can reuse the hash-table.
> We should also add compiler hints to `DataSet.reduceGroup()` and `Grouping.reduceGroup()` to allow users to select between a {{SORT}} and {{HASH}} based combine strategies ({{HASH}} will only be applicable to {{CombineFunction}} and not {{GroupCombineFunction}}).
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