Date: Fri, 20 Mar 1998 14:07:54 -0800 (PST) From: Simon Shapiro <shimon@simon-shapiro.org> To: Eivind Eklund <eivind@yes.no> Cc: roberto@keltia.freenix.fr, freebsd-hackers@FreeBSD.ORG, "Kent S. Gordon" <kgor@inetspace.com> Subject: Re: How do you increase available SYSV shared memory? Message-ID: <XFMail.980320140754.shimon@simon-shapiro.org> In-Reply-To: <19980320221931.51710@follo.net>
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On 20-Mar-98 Eivind Eklund wrote: > On Fri, Mar 20, 1998 at 12:32:19PM -0800, Simon Shapiro wrote: >> >> On 18-Mar-98 Kent S. Gordon wrote: >> > >> >>>>>> "shimon" == Simon Shapiro <shimon@simon-shapiro.org> writes: >> > I have been thinking of changing Postgres to use mmapped files instead >> > of SYSV shared memory. I think this should allow for larger postgres >> >> This will be a disaster. It assumes that PostgreSQL uses files for data >> storage. While this is the default mode, it is NOT the only storage >> meanager. In PostgreSQL, like most true RDBMS, the storage of data is >> decoupled from the logic of the relational model, etc. I am building a >> storage manager that uses a totally different (distributed) storage >> model >> than Unix files. A memory based storage manager already exists in >> PostgreSQL. Please do not break these. > > I don't think you're quite getting him (or I'm not getting you at all). > mmap()ing /dev/zero is a common way of getting hold of shared memory, > instead of using the SYSV SHMEM extension. mmap'ing usually works > better. > > This is just replacing one technique for getting hold of shared memory > with > another; it does nothing to the storage manager. Apologies then. I thought the intention was to mmap the storage manager. I am still recovering from a nasty cold and an all-night flight back home. The trip was worht it, though :-) ---------- Sincerely Yours, Simon Shapiro Shimon@Simon-Shapiro.ORG Voice: 503.799.2313 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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