Support CARDINALITY() in indexes#4100
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pengpeng-lu
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Apr 21, 2026
pengpeng-lu
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Apr 21, 2026
* Introduce a `CardinalityFunctionKeyExpression` to make it possible to
define indexes with a `function("cardinality", …)` key expression.
* In `MaterializedViewIndexGenerator`, add the necessary logic to
convert `CardinalityValue` into a key expression.
For a nullable ARRAY field, the key expression produced from a
`CARDINALITY(int_arr)` SQL expression will look as follows:
function("cardinality",
field("int_arr").nest(field("values", Concatenate)))
The use of the Concatenate fan-out type currently runs into some gaps
in the code that we also fix with this PR.
Testing:
* Integration tests in `arrays_cardinality.yamsql`.
* Unit tests in `IndexTest.java` and `KeyExpressionTest.java`.
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CardinalityFunctionKeyExpressionto make it possible to define indexes with afunction("cardinality", …)key expression.MaterializedViewIndexGenerator, add the necessary logic to convertCardinalityValueinto a key expression.For a nullable ARRAY field, the key expression produced from a
CARDINALITY(int_arr)SQL expression will look as follows:The use of the Concatenate fan-out type currently runs into some gaps in the code that we also fix with this PR.
Testing:
arrays_cardinality.yamsql.IndexTest.javaandKeyExpressionTest.java.