[SPARK-50418][SQL] Allow an optional trailing comma at the end of SELECT lists #48961
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dtenedor
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srielau
approved these changes
Nov 25, 2024
MaxGekk
reviewed
Nov 26, 2024
| @@ -5268,6 +5268,15 @@ object SQLConf { | |||
| .booleanConf | |||
| .createWithDefault(true) | |||
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| val OPTIONAL_TRAILING_COMMA_IN_NAMED_EXPRESSION_LISTS = | |||
| buildConf("spark.sql.optionalTrailingCommaInNamedExpressionLists") | |||
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The config name confuses slightly. I would think if it is true, the trailing comma is optional otherwise is mandatory ;-).
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| buildConf("spark.sql.optionalTrailingCommaInNamedExpressionLists") | |
| buildConf("spark.sql.allowTrailingCommaInNamedExpressionLists") |
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named expression list is not a user-facing concept, how about spark.sql.allowTrailingCommaInSelectList?
| test("SPARK-50418: Support an optional trailing comma at the end of SELECT lists") { | ||
| withSQLConf(SQLConf.OPTIONAL_TRAILING_COMMA_IN_NAMED_EXPRESSION_LISTS.key -> "true") { | ||
| assertEqual("select 1, ", OneRowRelation().select(1)) | ||
| assertEqual("select 1, 2", OneRowRelation().select(1, 2)) |
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nit: let's also test select 1, 2,
| withSQLConf(SQLConf.OPTIONAL_TRAILING_COMMA_IN_NAMED_EXPRESSION_LISTS.key -> "false") { | ||
| assertEqual("select 1, 2", OneRowRelation().select(1, 2)) | ||
| checkError( | ||
| exception = parseException("select 1,"), |
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nit: let's also test select 1, 2,
cloud-fan
reviewed
Nov 27, 2024
| @@ -425,7 +425,7 @@ org.apache.spark.sql.catalyst.parser.ParseException | |||
| "sqlState" : "42601", | |||
| "messageParameters" : { | |||
| "error" : "'BY'", | |||
| "hint" : ": extra input 'BY'" | |||
| "hint" : "" | |||
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why do we lose the hint?
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What changes were proposed in this pull request?
This PR extends the Spark SQL grammar to allow an optional trailing comma at the end of SELECT lists, and other named expression lists.
This behavior is controlled by the configuration
spark.sql.optionalTrailingCommaInNamedExpressionLists(SQLConf.get.OPTIONAL_TRAILING_COMMA_IN_NAMED_EXPRESSION_LISTS). The new configuration is true by default as of its introduction in this PR.For example, this query was not valid syntax before, but is now:
Why are the changes needed?
After deliberation, we decided it was useful to have this support to help with migration from other legacy databases.
Does this PR introduce any user-facing change?
Yes, see above.
How was this patch tested?
This PR adds unit test cases with the configuration enabled and disabled.
Was this patch authored or co-authored using generative AI tooling?
No.