[SPARK-10999] [SQL] Coalesce should be able to handle UnsafeRow #9024
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@JoshRosen This is the issue we discussed this afternoon. |
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LGTM |
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LGTM as well. |
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Jenkins, retest this please. |
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Test build #43388 has finished for PR 9024 at commit
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Thanks, I'm merging this to master. |
asfgit
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Sep 27, 2016
… formats ## What changes were proposed in this pull request? This patch addresses a correctness bug in Spark 1.6.x in where `coalesce()` declares that it can process `UnsafeRows` but mis-declares that it always outputs safe rows. If UnsafeRow and other Row types are compared for equality then we will get spurious `false` comparisons, leading to wrong answers in operators which perform whole-row comparison (such as `distinct()` or `except()`). An example of a query impacted by this bug is given in the [JIRA ticket](https://issues.apache.org/jira/browse/SPARK-17618). The problem is that the validity of our row format conversion rules depends on operators which handle `unsafeRows` (signalled by overriding `canProcessUnsafeRows`) correctly reporting their output row format (which is done by overriding `outputsUnsafeRows`). In #9024, we overrode `canProcessUnsafeRows` but forgot to override `outputsUnsafeRows`, leading to the incorrect `equals()` comparison. Our interface design is flawed because correctness depends on operators correctly overriding multiple methods this problem could have been prevented by a design which coupled row format methods / metadata into a single method / class so that all three methods had to be overridden at the same time. This patch addresses this issue by adding missing `outputsUnsafeRows` overrides. In order to ensure that bugs in this logic are uncovered sooner, I have modified `UnsafeRow.equals()` to throw an `IllegalArgumentException` if it is called with an object that is not an `UnsafeRow`. ## How was this patch tested? I believe that the stronger misuse-checking in `UnsafeRow.equals()` is sufficient to detect and prevent this class of bug. Author: Josh Rosen <joshrosen@databricks.com> Closes #15185 from JoshRosen/SPARK-17618.
zzcclp
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Sep 28, 2016
… formats ## What changes were proposed in this pull request? This patch addresses a correctness bug in Spark 1.6.x in where `coalesce()` declares that it can process `UnsafeRows` but mis-declares that it always outputs safe rows. If UnsafeRow and other Row types are compared for equality then we will get spurious `false` comparisons, leading to wrong answers in operators which perform whole-row comparison (such as `distinct()` or `except()`). An example of a query impacted by this bug is given in the [JIRA ticket](https://issues.apache.org/jira/browse/SPARK-17618). The problem is that the validity of our row format conversion rules depends on operators which handle `unsafeRows` (signalled by overriding `canProcessUnsafeRows`) correctly reporting their output row format (which is done by overriding `outputsUnsafeRows`). In apache#9024, we overrode `canProcessUnsafeRows` but forgot to override `outputsUnsafeRows`, leading to the incorrect `equals()` comparison. Our interface design is flawed because correctness depends on operators correctly overriding multiple methods this problem could have been prevented by a design which coupled row format methods / metadata into a single method / class so that all three methods had to be overridden at the same time. This patch addresses this issue by adding missing `outputsUnsafeRows` overrides. In order to ensure that bugs in this logic are uncovered sooner, I have modified `UnsafeRow.equals()` to throw an `IllegalArgumentException` if it is called with an object that is not an `UnsafeRow`. ## How was this patch tested? I believe that the stronger misuse-checking in `UnsafeRow.equals()` is sufficient to detect and prevent this class of bug. Author: Josh Rosen <joshrosen@databricks.com> Closes apache#15185 from JoshRosen/SPARK-17618. (cherry picked from commit e2ce0ca)
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