Hi,
I'm exploring Monet, and it's a very pleasant experience. I have a few questions however; please forgive the parade of ignorance that follows:
- If one creates persistent void-head BATs via MIL, is there a way to them as columns of a SQL table/view. I noticed the parser had a rule allowing "CREATE VIEW ... AS BATS", but wasn't quite sure how to use it.
- Conversely, if one has a set of tables, is there any easy way to find that mapping of columns to bat ids (e.g. so that one can lookup individual bats in MIL)? It appears this information is really only persisted in the log file, is that correct? If so, I assume the only other option would be to have the sql module loaded, and then access the temporary bats it creates that hold this metadata (I didn't notice that the module exported any MIL-accessible functions for grabbing the sql_column data)?
- I am wondering how transaction chains are supposed to behave w.r.t. memory consumption. Specifically, I noticed that when executing "savepoint x" in the mapiclient, the heap size of the Monet process climbs almost monotonically upwards - jumping perhaps 350K per savepoint (every tx is completely empty) and hardly falling at all following releases or rollbacks (or even client disconnect for that matter). My understanding is that a savepoint is essentially a child transaction (thus copied from the parent), in which case I'm worried it may not be releasing all resources related to the tx and therefore leaking memory? Or is it simply that monet is allocating additional space from the OS, say for BATs related to the transaction, and this memory is becoming part of the internal pool and thus not being release back to the OS? I'd assume the second except that I thought it would reuse the space so that the heap size would stop climbing after a while, and I never did reach that poi! nt even after 100's of savepoints and an 30-fold increase in heap size. (BTW, I'm running the pre-build MonetDB 4.6.0/SQL 2.6.0 on Win2K).
Many thanks for your time, and any responses.
Cheers, Jason