Re: [GENERAL] WAL directory size calculation

[Moreno Andreo]

Il 28/07/2016 15:33, David G. Johnston ha scritto: On Thu, Jul 28, 2016 at 9:25 AM, Moreno Andreo <moreno.and...@evolu-s.it> wrote: I've read somewhere that the formula should be 16 MB * 3 * checkpoint_segment in size. ​[...]​   Using the above formula I have:     16 MB * 3 * 1 GB that leads to to ... uh .. 48000 TB? ​You seem to be mis-remembering the formula.​ The result is too big to be sane... so there *must* be something wrong ​checkpoiint_segments is a quantity (i.e., unit-less), not a size.  Saying its "1GB" makes no sense. Yes, my "1 GB" is related to max_wal_file_size, that from 9.5 came over checkpoint_segment. ​I'm also doubting you multiply it by 3 - add three to it maybe... ​Each segment takes 16MB.  The total space required is that times whatever maximum count of segments you expect to have.​ That's the variable. How many segments do I expect to have? (jumping from 9.1 (current) to 9.5 (new) documentation and having a bit of confusion in my head...) I'd suggest waiting for better responses on these lists ...[snip]... Got one, in fact. The statement to *absolutely* not use ramdisk with wal files resolved almost all of my doubts. David J. Thanks Moreno