RE: Expectations of MEM requirements for a DB with large tables.
От | Michael Miyabara-McCaskey |
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Тема | RE: Expectations of MEM requirements for a DB with large tables. |
Дата | |
Msg-id | 000c01c047be$77da56d0$aa00a8c0@ncc1701e обсуждение исходный текст |
Ответ на | Re: Expectations of MEM requirements for a DB with large tables. (KuroiNeko <evpopkov@carrier.kiev.ua>) |
Список | pgsql-general |
Kuroi, Thank you for the response. I was not specifically thinking of diagnosing my crash, but if you are curious... - about a 1000 error messgaes saying that kswapd could not do something relating to allocating memory. - after stopping the "psql" job, it still took about 20 minutes before my Linux OS recovered enough to reboot. - yep, used "psql", plan on using Perl-DBI soon... I guess from your response I better make sure that whatever I use never does a full blown 'select *' on that table. - 2.2.17 from kernel.org, w/RAID patch. - PostgreSQL 7.0.2 was installed via the RPM from RedHat. - 98MB of RAM (this is a simple test system only) - 256MB of SWAP on a Linux SWAP Partition. - SWAP settings? Hmm... sorry this is where my novice level shows its colors, didn't know I could modify it. - Other processes, sure tons of them... Anyway, based upon your response, I understand that the 1 to 1 ratio is what crashed my system. Hmm, now you have me wondering though... I recall reading something that mentioned that data storage size in PostgreSQL is about 6 times the size of standard text, so, if my table size is about 5.5GB on the disk does this mean I really could only need about well say... 5.5GB / 6 = 936MB of RAM? Any idea? -Michael Miyabara-McCaskey > -----Original Message----- > From: pgsql-general-owner@postgresql.org > [mailto:pgsql-general-owner@postgresql.org]On Behalf Of KuroiNeko > Sent: Sunday, November 05, 2000 9:54 PM > To: pgsql-general@postgresql.org > Subject: Re: [GENERAL] Expectations of MEM requirements for a DB with > large tables. > > > > Mike, > > > Anyway, I crashed my system the other day when I did a > "select *" from > > one > > of my large tables (about 5.5gb in size). > > Well.... It takes abit more than that to actually crash > the system. Can > you give more details? What _exactly_ happened? Did it > hang? Kernel > panicked? Something else. > > > Does anyone know what the ratio of data output size (say > from a select) > > to > > the amount of > > RAM used is? > > It simply can't be other than 1 : 1. Well, in a sense. Did > you use psql? > Other app? If the latter, what interface: API, DBI, other? > Was it a local > or remote request? > > > Other relevant info, RedHat Linux 2.2.17 kernel, PostgreSQL 7.0.2. > > Is this a genuine kernel, or the one shipped by RH? Did > you build PGSQL > from sources or was it a pre-built binary? How much RAM do > you have, how > fast and big is your swap? Swap settings? Other processes running? > As you see, there are more questions than answers at this > stage. Tell us > more. Tuning the system has never been easy. >
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