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[GitHub] [spark] viirya opened a new pull request #35762: [SPARK-38443][SS][DOC] Document config STREAMING_SESSION_WINDOW_MERGE_SESSIONS_IN_LOCAL_PARTITION
viirya opened a new pull request #35762:
URL: https://github.com/apache/spark/pull/35762
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This proposes to document the config `spark.sql.streaming.sessionWindow.merge.sessions.in.local.partition` in structured streaming guide.
### Why are the changes needed?
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We have use case the customer faces issue on large shuffle write in session window. The config is hidden, although it is useful for such case. We should document it so end users can find it easily.
### Does this PR introduce _any_ user-facing change?
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Yes, documented a config in user-facing guide.
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Basically doc change.
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[GitHub] [spark] viirya commented on a change in pull request #35762: [SPARK-38443][SS][DOC] Document config STREAMING_SESSION_WINDOW_MERGE_SESSIONS_IN_LOCAL_PARTITION
Posted by GitBox <gi...@apache.org>.
viirya commented on a change in pull request #35762:
URL: https://github.com/apache/spark/pull/35762#discussion_r821914908
##########
File path: docs/structured-streaming-programming-guide.md
##########
@@ -1225,6 +1225,12 @@ Note that there are some restrictions when you use session window in streaming q
For batch query, global window (only having `session_window` in grouping key) is supported.
+Due to implementation details of session window in streaming query, for each input row in same session,
+it will be assigned initial session window and then merged into real session after shuffling. If the RPS
Review comment:
yea, let me revise it. Thanks.
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[GitHub] [spark] viirya commented on a change in pull request #35762: [SPARK-38443][SS][DOC] Document config STREAMING_SESSION_WINDOW_MERGE_SESSIONS_IN_LOCAL_PARTITION
Posted by GitBox <gi...@apache.org>.
viirya commented on a change in pull request #35762:
URL: https://github.com/apache/spark/pull/35762#discussion_r821402787
##########
File path: sql/catalyst/src/main/scala/org/apache/spark/sql/internal/SQLConf.scala
##########
@@ -1720,7 +1720,6 @@ object SQLConf {
val STREAMING_SESSION_WINDOW_MERGE_SESSIONS_IN_LOCAL_PARTITION =
buildConf("spark.sql.streaming.sessionWindow.merge.sessions.in.local.partition")
- .internal()
Review comment:
As we document it, seems strange to have it as internal. So I remove `internal` too.
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[GitHub] [spark] HeartSaVioR commented on a change in pull request #35762: [SPARK-38443][SS][DOC] Document config STREAMING_SESSION_WINDOW_MERGE_SESSIONS_IN_LOCAL_PARTITION
Posted by GitBox <gi...@apache.org>.
HeartSaVioR commented on a change in pull request #35762:
URL: https://github.com/apache/spark/pull/35762#discussion_r822169436
##########
File path: docs/structured-streaming-programming-guide.md
##########
@@ -1225,6 +1225,12 @@ Note that there are some restrictions when you use session window in streaming q
For batch query, global window (only having `session_window` in grouping key) is supported.
+Due to implementation details of session window in streaming query, for each input row in same session,
Review comment:
Why not explain the behavior of default and which case it helps? If we don't explain the case default is better, we fail to let end users reason about why this config exists, as well as why we disable this by default.
How about revising the content like this?
> By default, Spark does not perform partial aggregation for session window aggregation, since it requires additional sort in local partitions before grouping. It works better for the case there are only few number of input rows in same group key for each local partition, but for the case there are numerous input rows having same group key in local partition, doing partial aggregation can still increase the performance significantly despite additional sort.
>
> You can enable `spark.sql.streaming.sessionWindow.merge.sessions.in.local.partition` to indicate Spark to perform partial aggregation.
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[GitHub] [spark] viirya commented on a change in pull request #35762: [SPARK-38443][SS][DOC] Document config STREAMING_SESSION_WINDOW_MERGE_SESSIONS_IN_LOCAL_PARTITION
Posted by GitBox <gi...@apache.org>.
viirya commented on a change in pull request #35762:
URL: https://github.com/apache/spark/pull/35762#discussion_r822179554
##########
File path: docs/structured-streaming-programming-guide.md
##########
@@ -1225,6 +1225,12 @@ Note that there are some restrictions when you use session window in streaming q
For batch query, global window (only having `session_window` in grouping key) is supported.
+Due to implementation details of session window in streaming query, for each input row in same session,
Review comment:
I'm fine with revised content. The only point I have is to document it.
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[GitHub] [spark] dongjoon-hyun commented on a change in pull request #35762: [SPARK-38443][SS][DOC] Document config STREAMING_SESSION_WINDOW_MERGE_SESSIONS_IN_LOCAL_PARTITION
Posted by GitBox <gi...@apache.org>.
dongjoon-hyun commented on a change in pull request #35762:
URL: https://github.com/apache/spark/pull/35762#discussion_r821904469
##########
File path: docs/structured-streaming-programming-guide.md
##########
@@ -1225,6 +1225,12 @@ Note that there are some restrictions when you use session window in streaming q
For batch query, global window (only having `session_window` in grouping key) is supported.
+Due to implementation details of session window in streaming query, for each input row in same session,
+it will be assigned initial session window and then merged into real session after shuffling. If the RPS
Review comment:
Shall we use the full word instead of `RPS`?
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[GitHub] [spark] viirya commented on pull request #35762: [SPARK-38443][SS][DOC] Document config STREAMING_SESSION_WINDOW_MERGE_SESSIONS_IN_LOCAL_PARTITION
Posted by GitBox <gi...@apache.org>.
viirya commented on pull request #35762:
URL: https://github.com/apache/spark/pull/35762#issuecomment-1062090556
Thank you @dongjoon-hyun
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[GitHub] [spark] HeartSaVioR commented on a change in pull request #35762: [SPARK-38443][SS][DOC] Document config STREAMING_SESSION_WINDOW_MERGE_SESSIONS_IN_LOCAL_PARTITION
Posted by GitBox <gi...@apache.org>.
HeartSaVioR commented on a change in pull request #35762:
URL: https://github.com/apache/spark/pull/35762#discussion_r822169436
##########
File path: docs/structured-streaming-programming-guide.md
##########
@@ -1225,6 +1225,12 @@ Note that there are some restrictions when you use session window in streaming q
For batch query, global window (only having `session_window` in grouping key) is supported.
+Due to implementation details of session window in streaming query, for each input row in same session,
Review comment:
Why not explain the behavior of default and which case it helps? If we don't explain the case default is better, we fail to let end users reason about why this config exists, as well as why we disable this by default.
How about revising the content like this?
````
By default, Spark does not perform partial aggregation for session window aggregation, since it requires additional sort in local partitions before grouping. It works better for the case there are only few number of input rows in same group key for each local partition, but for the case there are numerous input rows having same group key in local partition, doing partial aggregation can still increase the performance significantly despite additional sort.
You can enable `spark.sql.streaming.sessionWindow.merge.sessions.in.local.partition` to indicate Spark to perform partial aggregation.
```
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[GitHub] [spark] viirya commented on pull request #35762: [SPARK-38443][SS][DOC] Document config STREAMING_SESSION_WINDOW_MERGE_SESSIONS_IN_LOCAL_PARTITION
Posted by GitBox <gi...@apache.org>.
viirya commented on pull request #35762:
URL: https://github.com/apache/spark/pull/35762#issuecomment-1062447722
Thanks @dongjoon-hyun @HeartSaVioR . Merging to master.
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[GitHub] [spark] viirya commented on a change in pull request #35762: [SPARK-38443][SS][DOC] Document config STREAMING_SESSION_WINDOW_MERGE_SESSIONS_IN_LOCAL_PARTITION
Posted by GitBox <gi...@apache.org>.
viirya commented on a change in pull request #35762:
URL: https://github.com/apache/spark/pull/35762#discussion_r822181345
##########
File path: docs/structured-streaming-programming-guide.md
##########
@@ -1225,6 +1225,12 @@ Note that there are some restrictions when you use session window in streaming q
For batch query, global window (only having `session_window` in grouping key) is supported.
+Due to implementation details of session window in streaming query, for each input row in same session,
Review comment:
Revised based on your comment. If no question, I will merge it.
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[GitHub] [spark] viirya closed pull request #35762: [SPARK-38443][SS][DOC] Document config STREAMING_SESSION_WINDOW_MERGE_SESSIONS_IN_LOCAL_PARTITION
Posted by GitBox <gi...@apache.org>.
viirya closed pull request #35762:
URL: https://github.com/apache/spark/pull/35762
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[GitHub] [spark] viirya commented on pull request #35762: [SPARK-38443][SS][DOC] Document config STREAMING_SESSION_WINDOW_MERGE_SESSIONS_IN_LOCAL_PARTITION
Posted by GitBox <gi...@apache.org>.
viirya commented on pull request #35762:
URL: https://github.com/apache/spark/pull/35762#issuecomment-1062020287
cc @dongjoon-hyun @HeartSaVioR
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