Hello,

I have recently discovered issue with function org.h2.schema.FunctionAlias.JavaMethod#resultSetToResult which leaves ResultSet rs passed in argument unclosed, when int maxrows =0 (we are reading only column metadata, not full data).

When we read all rows, after the last row (next() == null) result set is closed, but we only read metadata result set is kept hanging open. It is an issue, when for custom JavaTableFunction we use a file based result set, as we end up with lots of open file handlers.

For now based on https://github.com/h2database/h2database/blob/45b609dec0e45125e6a93f85c9018d34551332a1/h2/src/test/org/h2/samples/Function.java getMatrix example, we were able to inject Connection in our function and in case of when conn.getMetaData().getURL().equals("jdbc:columnlist:connection") we return a new SimpleResultSet with only column metadata set, and only otherwise File based result set, but in our opinion that result sets used in resultSetToResult should be closed by library, not by us.