SQL: Use specialized virtual columns for JSON_OBJECT, JSON_MERGE. #18553
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gianm
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Building on apache#18521, this patch makes virtual column specialization recursive. It also now happens immediately on calling getOrCreateVirtualColumnForExpression. Specializations are added for JSON_OBJECT and JSON_MERGE. Now, chains of JSON_MERGE, JSON_OBJECT, and JSON_VALUE can preserve lazy evaluation, index usage, dictionary usage, etc. There is a change to VirtualColumnCreator that can affect extensions that add SQL operators. To allow the creator to access rewritten arguments, a "DruidExpression self" parameter is added. The "String expression" is no longer needed so it is removed.
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clintropolis
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Oct 9, 2025
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| final boolean forceExpressionVirtualColumns = | ||
| plannerContext.getPlannerConfig().isForceExpressionVirtualColumns(); |
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it seems like this flag is no longer honored, should we push the config into the virtual column registry?
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I did do that, it's pushed in and if true then VirtualColumnRegistry#specialize exits without doing anything.
clintropolis
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Oct 15, 2025
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Building on #18521, this patch makes virtual column specialization recursive and adds specializations for two additional JSON functions. The result is that chains of JSON_OBJECT, JSON_MERGE, and JSON_VALUE can preserve lazy evaluation, index usage, dictionary usage, etc.
There is a change to VirtualColumnCreator that can affect extensions that add SQL operators. To allow the creator to access rewritten arguments, a "DruidExpression self" parameter is added. The "String expression" is no longer needed so it is removed.