Evgenij Ryazanov

@forchid Please, compile H2 (or MVStore) from the current sources and run your tests again.

If logarithmic amount of memory is required, everything works as expected and there is nothing to fix.

Only [BACKUP](https://h2database.com/html/commands.html#backup) and [SCRIPT](https://h2database.com/html/commands.html#script) commands may be used for backup copies, attempt to copy database files when database is online is a way to get a corrupted copy.

I'm not opposed to this idea with multiple files, but on high transaction per second rate an own file for each version can decrease performance. Also it would be nice...

This sounds good.

We need some efficient online compaction procedure. Our offline compaction creates a new file and online compaction may need this too.

It wasn't a real uncontrolled memory leak problem, it was an incorrect memory size estimation with a very low impact on real-world applications with large databases, normal memory size of...

You may want to suggest a `FILTER` clause to exclude nulls from aggregation, because row value with nulls will be aggregated otherwise.

Do you mean `ALTER TABLE [ IF EXISTS ] tableName ALTER COLUMN [ IF EXISTS ] columnName`? H2 supports `IF EXISTS` clause for a table for a long time and...

H2 1.4.200 was released (not yet visible in Maven Central).