Hi Sage, I notice your post in rocksdb page about make rocksdb aware of short alive key/value pairs. I think it would be great if one keyvalue db impl could support different key types with different store behaviors. But it looks like difficult for me to add this feature to an existing db. So combine my experience with filestore, I just think let NewStore/FileStore aware of this short-alive keys(Or just PGLog keys) could be easy and effective. PGLog owned by PG and maintain the history of ops. It's alike Journal Data but only have several hundreds bytes. Actually we only need to have several hundreds MB at most to store all pgs pglog. For FileStore, we already have FileJournal have a copy of PGLog, previously I always think about reduce another copy in leveldb to reduce leveldb calls which consumes lots of cpu cycles. But it need a lot of works to be done in FileJournal to aware of pglog things. NewStore doesn't use FileJournal and it should be easier to settle down my idea(?). Actually I think a rados write op in current objectstore impl that omap key/value pairs hurts performance hugely. Lots of cpu cycles are consumed and contributes to short-alive keys(pglog). It should be a obvious optimization point. In the other hands, pglog is dull and doesn't need rich keyvalue api supports. Maybe a lightweight filejournal to settle down pglogs keys is also worth to try. In short, I think it would be cleaner and easier than improving rocksdb to impl a pglog-optimization structure to store this. PS(off topic): a keyvaluedb benchmark http://sphia.org/benchmarks.html -- Best Regards, Wheat -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
