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testkit(derby): close(key) drops the key's in-memory database; a hash join may hold 64 MB of a table - #69
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Derby keeps an in-memory database for the whole JVM until it is dropped, its connections closed or not. A caller that opens one database per key gives it back with close(key), as with H2 and DuckDB; close() drops every database the provider opened. Signed-off-by: Stefan Bischof <stbischof@bipolis.org>
Derby gives a hash join 1 MB per table by default and joins a larger derived table by nested loops, once per row of the other side. The test kit raises derby.language.maxMemoryPerTable to 64 MB. Signed-off-by: Stefan Bischof <stbischof@bipolis.org>
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DerbyDatabaseProvider.close(key)drops the in-memory database of the key (drop=true), as the H2 and DuckDB providers do;close()drops every database the provider opened.derby.language.maxMemoryPerTableto 64 MB where it is not set: above 1 MB per table, Derby's default, it joins a derived table by nested loops instead of a hash join.