Re: WAL directory size calculation - Mailing list pgsql-general
From | Moreno Andreo |
---|---|
Subject | Re: WAL directory size calculation |
Date | |
Msg-id | 6d49d526-70d4-0005-fea9-360ee1b59825@evolu-s.it Whole thread Raw |
In response to | Re: WAL directory size calculation ("David G. Johnston" <david.g.johnston@gmail.com>) |
List | pgsql-general |
Il 28/07/2016 15:33, David G. Johnston ha scritto: <blockquote cite="mid:CAKFQuwaMGb-qMnf0T0F35NQg_FidzVugnBYhSz3AybMwkwppOg@mail.gmail.com" type="cite"> <div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><span style="font-family:arial,sans-serif">On Thu, Jul 28, 2016 at 9:25 AM, Moreno Andreo <span dir="ltr" style="font-family:arial,sans-serif"><<a moz-do-not-send="true" href="mailto:moreno.andreo@evolu-s.it" target="_blank">moreno.andreo@evolu-s.it><span style="font-family:arial,sans-serif"> wrote: <blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex">I've read somewhere that the formula should be 16 MB * 3 * checkpoint_segment in size. <div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">â[...]â  <blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex">Using the above formula I have:   16 MB * 3 * 1 GB that leads to to ... uh .. 48000 TB? <div class="gmail_default" style="font-family:arial,helvetica,sans-serif">âYou seem to be mis-remembering the formula.â The result is too big to be sane... so there *must* be something wrong <blockquote cite="mid:CAKFQuwaMGb-qMnf0T0F35NQg_FidzVugnBYhSz3AybMwkwppOg@mail.gmail.com" type="cite"> <div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">âcheckpoiint_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. <blockquote cite="mid:CAKFQuwaMGb-qMnf0T0F35NQg_FidzVugnBYhSz3AybMwkwppOg@mail.gmail.com" type="cite"> <div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> <div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">âI'm also doubting you multiply it by 3 - add three to it maybe... <div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"> <div class="gmail_default" style="font-family:arial,helvetica,sans-serif">âEach segment takes 16MB. The total space required is that times whatever maximum count of segments you expect to have.â 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...) <blockquote cite="mid:CAKFQuwaMGb-qMnf0T0F35NQg_FidzVugnBYhSz3AybMwkwppOg@mail.gmail.com" type="cite"> <div class="gmail_default" style="font-family:arial,helvetica,sans-serif"> <div class="gmail_default" style="font-family:arial,helvetica,sans-serif">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. <blockquote cite="mid:CAKFQuwaMGb-qMnf0T0F35NQg_FidzVugnBYhSz3AybMwkwppOg@mail.gmail.com" type="cite"> <div class="gmail_default" style="font-family:arial,helvetica,sans-serif"> <div class="gmail_default" style="font-family:arial,helvetica,sans-serif">David J. Thanks Moreno
pgsql-general by date: