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hsqldb

HSQLDB triggers OutOfMemoryError when using nested queries and the DB is in read-only mode

For a complex use case with about 300000 queries we are using HSQLDB in read-only mode. After a short time, we run into an OutOfMemoryError.

The problem is the combination of sub-select queries and read only, all other combinations work fine and fast:

               simple select   nested select
DB read only   works           OOM
DB read/write  works           works

Here is a simple reproducer including a (read only) data base for the reproducer.

To switch to a read/write DB, simple delete the line "readonly=true" in repo.properties and run the test again.

I suspect that the RowStoreAVLHybridclass is part of the problem, because that class only is used in the subselect+read-only case.

Any idea what i can do besides switching the database to read/write, what i want to avoid at all cost?

Solution

  • There was no workaround for this bug. It has been resovled and a fix committed to the dev-three code branch for the HSQLDB version 2.5.0 release.