4 ms·
It has a single writer transaction mutex, yes. But it's a process-shared mutex, so it will serialize write transactions across an arbitrary number of processes.
by hyc_symas 11mo ago
It has a single writer transaction mutex, yes. But it's a process-shared mutex, so it will serialize write transactions across an arbitrary number of processes. And of course, read transactions are completely lockfree/waitfree across arbitrarily many processes.
As for working set size, that is always merely the height of the B+tree. Scans won't change that. It will always be far more efficient than any other DB under the same conditions.
- otterley 11mo ago> As for working set size, that is always merely the height of the B+tree. This statement makes no sense to me. Are you using a different definition of "working set" than the rest of us? A working set size is application and access pattern dependent. > It will always be far more efficient than any other DB under the same conditions That depends on how broadly or narrowly one defines "same conditions" :-)
- hyc_symas 11mo agoIdentical hardware, same RAM size, same data volume.
- otterley 11mo agoThat’s a bold claim. Are you saying that LMDB outperforms every other database on the same hardware, regardless of access pattern? And if so, is there proof of this?
- hyc_symas 11mo agoPlenty of proof. http://www.lmdb.tech/bench/ http://www.lmdb.tech/bench/
- otterley 11mo agoSince the first question of my two-part inquiry not explicitly answered in the affirmative: To be absolutely clear, you are claiming, in writing, that LMDB outperforms every other database there is, regardless of access pattern, using the same hardware?
- hyc_symas 11mo agoNot every. LMDB is optimized for read-heavy workloads. I make no particular claims about write-heavy workloads. Because it's so efficient, it can retain more useful data in-memory than other DBs for a given RAM size. For DBs much larger than RAM it will get more useful work done with the available RAM than other DBs. You can examine the benchmark reports linked above, they provide not just the data but also the analysis of why the results are as they are.
- hyc_symas 11mo agoYou don't have to take my word for it. Plenty of other developers know. https://www.youtube.com/watch?v=CfiQ0h4bGWM https://www.youtube.com/watch?v=CfiQ0h4bGWM