[SPARK-56390][SQL] Avoid throwing away resolved child when constructing V1 command variants of ShowColumns and DescribeRelation#55247
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let's use the resolved child in the |
cloud-fan
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Apr 9, 2026
| val catalog = sparkSession.sessionState.catalog | ||
| // V2SessionCatalog.loadTable uses getTableMetadata which replaces char/varchar with string | ||
| // in the CatalogTable schema. Restore the original types from field metadata so that | ||
| // DESCRIBE TABLE reports char(n)/varchar(n) instead of string. |
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this is a good catch! shall we do CharVarcharUtils.getRawSchema in the util function ResolvedChildHelper.getTableMetadata? SHOW COLUMNS should report char/varchar instead of string as well.
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What changes were proposed in this pull request?
ResolveSessionCatalog transforms
DescribeRelation(DESCRIBE TABLE) toDescribeTableCommandandShowColumnstoShowColumnsCommandin some scenarios. While doing so, it throws away the resolved entity information. This PR, adds a childLogicalPlantoShowColumnsCommandandDescribeTableCommandto store this resolved entity just like their V2 counterpartsShowColumnsandDescribeRelation.Why are the changes needed?
By storing the resolved entity in the V1 command variants, we can avoid throwing away useful info that can help us avoid extra catalog lookups.
Does this PR introduce any user-facing change?
No
How was this patch tested?
Ran PlanResolutionSuite and SQLQueryTestSuite
Was this patch authored or co-authored using generative AI tooling?
No