[SPARK-22862] Docs on lazy elimination of columns missing from an enc… #1
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…oder This behavior has confused some users, so lets clarify it. Author: Michael Armbrust <[email protected]> Closes #20048 from marmbrus/datasetAsDocs. (cherry picked from commit 8df1da3) Signed-off-by: gatorsmile <[email protected]>
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## What changes were proposed in this pull request? There were two related fixes regarding `from_json`, `get_json_object` and `json_tuple` ([Fix #1](apache@c8803c0), [Fix #2](apache@86174ea)), but they weren't comprehensive it seems. I wanted to extend those fixes to all the parsers, and add tests for each case. ## How was this patch tested? Regression tests Author: Burak Yavuz <[email protected]> Closes apache#20302 from brkyvz/json-invfix.
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## What changes were proposed in this pull request? There were two related fixes regarding `from_json`, `get_json_object` and `json_tuple` ([Fix #1](apache@c8803c0), [Fix #2](apache@86174ea)), but they weren't comprehensive it seems. I wanted to extend those fixes to all the parsers, and add tests for each case. ## How was this patch tested? Regression tests Author: Burak Yavuz <[email protected]> Closes apache#20302 from brkyvz/json-invfix. (cherry picked from commit e01919e) Signed-off-by: hyukjinkwon <[email protected]>
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## What changes were proposed in this pull request?
Solved two bugs to enable stream-stream self joins.
### Incorrect analysis due to missing MultiInstanceRelation trait
Streaming leaf nodes did not extend MultiInstanceRelation, which is necessary for the catalyst analyzer to convert the self-join logical plan DAG into a tree (by creating new instances of the leaf relations). This was causing the error `Failure when resolving conflicting references in Join:` (see JIRA for details).
### Incorrect attribute rewrite when splicing batch plans in MicroBatchExecution
When splicing the source's batch plan into the streaming plan (by replacing the StreamingExecutionPlan), we were rewriting the attribute reference in the streaming plan with the new attribute references from the batch plan. This was incorrectly handling the scenario when multiple StreamingExecutionRelation point to the same source, and therefore eventually point to the same batch plan returned by the source. Here is an example query, and its corresponding plan transformations.
```
val df = input.toDF
val join =
df.select('value % 5 as "key", 'value).join(
df.select('value % 5 as "key", 'value), "key")
```
Streaming logical plan before splicing the batch plan
```
Project [key#6, value#1, value#12]
+- Join Inner, (key#6 = key#9)
:- Project [(value#1 % 5) AS key#6, value#1]
: +- StreamingExecutionRelation Memory[#1], value#1
+- Project [(value#12 % 5) AS key#9, value#12]
+- StreamingExecutionRelation Memory[#1], value#12 // two different leaves pointing to same source
```
Batch logical plan after splicing the batch plan and before rewriting
```
Project [key#6, value#1, value#12]
+- Join Inner, (key#6 = key#9)
:- Project [(value#1 % 5) AS key#6, value#1]
: +- LocalRelation [value#66] // replaces StreamingExecutionRelation Memory[#1], value#1
+- Project [(value#12 % 5) AS key#9, value#12]
+- LocalRelation [value#66] // replaces StreamingExecutionRelation Memory[#1], value#12
```
Batch logical plan after rewriting the attributes. Specifically, for spliced, the new output attributes (value#66) replace the earlier output attributes (value#12, and value#1, one for each StreamingExecutionRelation).
```
Project [key#6, value#66, value#66] // both value#1 and value#12 replaces by value#66
+- Join Inner, (key#6 = key#9)
:- Project [(value#66 % 5) AS key#6, value#66]
: +- LocalRelation [value#66]
+- Project [(value#66 % 5) AS key#9, value#66]
+- LocalRelation [value#66]
```
This causes the optimizer to eliminate value#66 from one side of the join.
```
Project [key#6, value#66, value#66]
+- Join Inner, (key#6 = key#9)
:- Project [(value#66 % 5) AS key#6, value#66]
: +- LocalRelation [value#66]
+- Project [(value#66 % 5) AS key#9] // this does not generate value, incorrect join results
+- LocalRelation [value#66]
```
**Solution**: Instead of rewriting attributes, use a Project to introduce aliases between the output attribute references and the new reference generated by the spliced plans. The analyzer and optimizer will take care of the rest.
```
Project [key#6, value#1, value#12]
+- Join Inner, (key#6 = key#9)
:- Project [(value#1 % 5) AS key#6, value#1]
: +- Project [value#66 AS value#1] // solution: project with aliases
: +- LocalRelation [value#66]
+- Project [(value#12 % 5) AS key#9, value#12]
+- Project [value#66 AS value#12] // solution: project with aliases
+- LocalRelation [value#66]
```
## How was this patch tested?
New unit test
Author: Tathagata Das <[email protected]>
Closes apache#20598 from tdas/SPARK-23406.
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…oder
This behavior has confused some users, so lets clarify it.
Author: Michael Armbrust [email protected]
Closes apache#20048 from marmbrus/datasetAsDocs.
(cherry picked from commit 8df1da3)
Signed-off-by: gatorsmile [email protected]
What changes were proposed in this pull request?
(Please fill in changes proposed in this fix)
How was this patch tested?
(Please explain how this patch was tested. E.g. unit tests, integration tests, manual tests)
(If this patch involves UI changes, please attach a screenshot; otherwise, remove this)
Please review http://spark.apache.org/contributing.html before opening a pull request.