gengliangwang commented on code in PR #46312:
URL: https://github.com/apache/spark/pull/46312#discussion_r1586809054
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sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/ResolveDefaultColumnsUtil.scala:
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@@ -84,9 +84,16 @@ object ResolveDefaultColumns extends QueryErrorsBase
if (SQLConf.get.enableDefaultColumns) {
val newFields: Seq[StructField] = tableSchema.fields.map { field =>
if (field.metadata.contains(CURRENT_DEFAULT_COLUMN_METADATA_KEY)) {
- val analyzed: Expression = analyze(field, statementType)
+ val defaultSql: String = if
(field.dataType.isInstanceOf[VariantType]) {
+ // A variant's SQL/string representation is its JSON string which
cannot be directly
+ // casted to a variant type. Thus, we lazily evaluate the default
expression to avoid
Review Comment:
> analyze the sql text {'k': 'v'}
shouldn't it be sql text `parse_json('{'k': 'v'}')`? I am confusing...
> create a string literal from {'k': 'v'} and wrap it with parse_json
(effectively coercing it to the correct variant type). This feels inefficient,
however, because we have variant->string->variant conversion rather than lazily
evaluating it once
Since the `analyze` will perform `ConstantFolding`, it would be great if we
can unify the code path here. The overhead is trivial here.
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