[SPARK-34359][SQL] Add a legacy config to restore the output schema of SHOW DATABASES #31474
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cloud-fan
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Feb 4, 2021
| namespace: LogicalPlan, | ||
| pattern: Option[String]) extends Command { | ||
| pattern: Option[String], | ||
| override val output: Seq[Attribute] = ShowNamespaces.OUTPUT) extends Command { |
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I think it's better to put the output field in the constructor so that it's more stable (copying the node will not regenerate the output attributes again). It also helps if we want to support self-join later.
cloud-fan
commented
Feb 4, 2021
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| test("SPARK-34359: keep the legacy output schema") { | ||
| withSQLConf(SQLConf.LEGACY_KEEP_COMMAND_OUTPUT_SCHEMA.key -> "true") { | ||
| assert(sql("SHOW NAMESPACES").schema.fieldNames.toSeq == Seq("databaseName")) |
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Usually, people don't rely on the output schema of commands, but some BI tools may rely on it and users are not able to update the BI tools. That's why I think it deserves a legacy config.
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Usually, people don't rely on the output schema of commands, but some BI tools may rely on it and users are not able to update the BI tools. That's why I think it deserves a legacy config.
That's an important reason. +1 for this.
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Test build #134877 has finished for PR 31474 at commit
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maropu
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Feb 5, 2021
dongjoon-hyun
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Co-authored-by: Hyukjin Kwon <gurwls223@gmail.com>
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The last commit just updates the migration guide, I'm merging it to master, thanks all for the review! I'll backport it 3.1/3.0 soon. |
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…f SHOW DATABASES This is a followup of apache#26006 In apache#26006 , we merged the v1 and v2 SHOW DATABASES/NAMESPACES commands, but we missed a behavior change that the output schema of SHOW DATABASES becomes different. This PR adds a legacy config to restore the old schema, with a migration guide item to mention this behavior change. Improve backward compatibility No (the legacy config is false by default) a new test Closes apache#31474 from cloud-fan/command-schema. Lead-authored-by: Wenchen Fan <cloud0fan@gmail.com> Co-authored-by: Wenchen Fan <wenchen@databricks.com> Signed-off-by: Wenchen Fan <wenchen@databricks.com>
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…ema of SHOW DATABASES This backports #31474 to 3.1/3.0 ### What changes were proposed in this pull request? This is a followup of #26006 In #26006 , we merged the v1 and v2 SHOW DATABASES/NAMESPACES commands, but we missed a behavior change that the output schema of SHOW DATABASES becomes different. This PR adds a legacy config to restore the old schema, with a migration guide item to mention this behavior change. ### Why are the changes needed? Improve backward compatibility ### Does this PR introduce _any_ user-facing change? No (the legacy config is false by default) ### How was this patch tested? a new test Closes #31486 from cloud-fan/command-schema. Authored-by: Wenchen Fan <cloud0fan@gmail.com> Signed-off-by: Wenchen Fan <wenchen@databricks.com>
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…ema of SHOW DATABASES This backports #31474 to 3.1/3.0 This is a followup of #26006 In #26006 , we merged the v1 and v2 SHOW DATABASES/NAMESPACES commands, but we missed a behavior change that the output schema of SHOW DATABASES becomes different. This PR adds a legacy config to restore the old schema, with a migration guide item to mention this behavior change. Improve backward compatibility No (the legacy config is false by default) a new test Closes #31486 from cloud-fan/command-schema. Authored-by: Wenchen Fan <cloud0fan@gmail.com> Signed-off-by: Wenchen Fan <wenchen@databricks.com> (cherry picked from commit 7c87b48) Signed-off-by: Wenchen Fan <wenchen@databricks.com>
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What changes were proposed in this pull request?
This is a followup of #26006
In #26006 , we merged the v1 and v2 SHOW DATABASES/NAMESPACES commands, but we missed a behavior change that the output schema of SHOW DATABASES becomes different.
This PR adds a legacy config to restore the old schema, with a migration guide item to mention this behavior change.
Why are the changes needed?
Improve backward compatibility
Does this PR introduce any user-facing change?
No (the legacy config is false by default)
How was this patch tested?
a new test