* Andres Freund (and...@2ndquadrant.com) wrote: > > 1. I've decided to put pg_stat_lwlock into extension pg_stat_lwlock > > (simply for test purposes). Is it OK, or better to implement it > > somewhere inside pg_catalog or in another extension (for example > > pg_stat_statements)? > > I personally am doubtful that it makes much sense to move this into an > extension. It'll likely be tightly enough interlinked to backend code > that I don't see the point. But I'd not be surprised if others feel > differently.
I agree that this doesn't make sense as an extension. > I generally don't think you'll get interesting data without a fair bit > of additional work. I'm not sure about this.. > The first problem that comes to my mind about collecting enough data is > that we have a very large number of lwlocks (fixed_number + 2 * > shared_buffers). One 'trivial' way of implementing this is to have a per > backend array collecting the information, and then a shared one > accumulating data from it over time. But I'm afraid that's not going to > fly :(. Hm. With the above sets of stats that'd be ~50MB per backend... I was just going to suggest exactly this- a per-backend array which then gets pushed into a shared area periodically. Taking up 50MB per backend is quite a bit though. :/ > Perhaps we should somehow encode this different for individual lwlock > tranches? It's far less problematic to collect all this information for > all but the buffer lwlocks... Yeah, that seems like it would at least be a good approach to begin with. Thanks, Stephen
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