Reintroduce fix for dynamic pruning for with null keys in hive partition#16261
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pettyjamesm merged 2 commits intoprestodb:masterfrom Jun 21, 2021
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This reverts commit 72a7afc.
When encoded as partition names, null column values in Hive use a magic string: __HIVE_DEFAULT_PARTITION__. In other places though, null values are represented with the sequence \N. This creates an unfortunate ambiguity whereby a non-null partition value of "\N" could subsequently be interpreted as null in some value contexts such as prefilled values or for the purposes of dynamic filtering. Instead of converting "__HIVE_DEFAULT_PARTITION__" to "\N" in its constructor, HivePartitionKey will instead carry Optional<String> for its value and rely on callers to use the appropriate null string for their context.
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Fixes dynamic pruning when null values are present by reintroducing changes from #15470 (previously reverted in #16061).
#16061 appears to have chosen to revert the previous fix because partitions with a non-null value of "\N" in the name could accidentally be interpreted as null which they should not have been.
This change avoids converting
"__HIVE_DEFAULT_PARTITION__"to"\N"in theHivePartitionKeyconstructor and propagatesOptional<String>as the value instead. Callers must now perform a context-appropriate conversion for null strings at their usage site.