Thread: Re: [GENERAL] Linux Largefile Support In Postgresql RPMS
Ralph Graulich wrote: >Hi, > >just my two cents worth: I like having the files sized in a way I can >handle them easily with any UNIX tool on nearly any system. No matter >wether I want to cp, tar, dump, dd, cat or gzip the file: Just keep it at >a maximum size below any limits, handy for handling. > Good point... however I was thinking that being able to dump the entire database without resporting to "gzips and splits" was handy... > >For example, Oracle suggests it somewhere in their documentation, to keep >datafiles at a reasonable size, e.g. 1 GB. Seems right to me, never had >any problems with it. > Yep, fixed or controlled sizes for data files is great... I was thinking about databases rather than data files (altho I may not have made that clear in my mail) best wishes Mark
On Sat, 2002-08-10 at 00:25, Mark Kirkwood wrote: > Ralph Graulich wrote: > > >Hi, > > > >just my two cents worth: I like having the files sized in a way I can > >handle them easily with any UNIX tool on nearly any system. No matter > >wether I want to cp, tar, dump, dd, cat or gzip the file: Just keep it at > >a maximum size below any limits, handy for handling. > > > Good point... however I was thinking that being able to dump the entire > database without resporting to "gzips and splits" was handy... > > > > >For example, Oracle suggests it somewhere in their documentation, to keep > >datafiles at a reasonable size, e.g. 1 GB. Seems right to me, never had > >any problems with it. > > > Yep, fixed or controlled sizes for data files is great... I was thinking > about databases rather than data files (altho I may not have made that > clear in my mail) > I'm actually amazed that postgres isn't already using large file support. Especially for tools like dump. I do recognize the need to keep files manageable in size but my file sizes for my needs may differ from your sizing needs. Seems like it would be a good thing to enable and simply make it a function for the DBA to handle. After all, even if I'm trying to keep my dumps at around 1GB, I probably would be okay with a dump of 1.1GB too. To me, that just seems more flexible. Greg
On Sat, Aug 10, 2002 at 09:21:07AM -0500, Greg Copeland wrote:
> I'm actually amazed that postgres isn't already using large file
> support. Especially for tools like dump.
Except it would only cause confusion if you ran such a program on a
system that didn't itself have largefile support. Better to make the
admin turn all these things on on purpose, until everyone is running
64 bit systems everywhere.
A
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Andrew Sullivan 87 Mowat Avenue
Liberty RMS Toronto, Ontario Canada
<andrew@libertyrms.info> M6K 3E3
+1 416 646 3304 x110
On Mon, 2002-08-12 at 09:39, Andrew Sullivan wrote: > On Sat, Aug 10, 2002 at 09:21:07AM -0500, Greg Copeland wrote: > > > I'm actually amazed that postgres isn't already using large file > > support. Especially for tools like dump. > > Except it would only cause confusion if you ran such a program on a > system that didn't itself have largefile support. Better to make the > admin turn all these things on on purpose, until everyone is running > 64 bit systems everywhere. If by "turn...on", you mean recompile, that's a horrible idea IMO. Besides, you're expecting that an admin is going to know that he even needs to recompile to obtain this feature let alone that he'd interested in compiling his own installation. Whereas, more then likely he'll know off hand (or can easily find out) if his FS/system supports large files (>32 bit sizes). Seems like, systems which can natively support this feature should have it enabled by default. It's a different issue if an admin attempts to create files larger than what his system and/or FS can support. I guess what I'm trying to say here is, it's moving the problem from being a postgres specific issue (not compiled in -- having to recompile and install and not knowing if it's (dis)enabled) to a general body of knowledge (does my system support such-n-such capabilities). If a recompile time is still much preferred by the core developers, perhaps a log entry can be created which at least denotes the current status of such a feature when a compile time option is required. Simply having an entry of, "LOG: LARGE FILE SUPPORT (DIS)ENABLED (64-bit file sizes)", etc...things along those lines. Of course, having a "--enable-large-files" would be nice too. This would seemingly make sense in other contexts too. Imagine a back-end compiled with large file support and someone else using fe tools which does not support it. How are they going to know if their fe/be supports this feature unless we let them know? Greg
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On Mon, Aug 12, 2002 at 10:15:46AM -0500, Greg Copeland wrote:
> If by "turn...on", you mean recompile, that's a horrible idea IMO.
Ah. Well, that is what I meant. Why is it horrible? PostgreSQL
doesn't take very long to compile.
> I guess what I'm trying to say here is, it's moving the problem from
> being a postgres specific issue (not compiled in -- having to recompile
> and install and not knowing if it's (dis)enabled) to a general body of
> knowledge (does my system support such-n-such capabilities).
The problem is not just a system-level one, but a filesystem-level
one. Enabling 64 bits by default might be dangerous, because a DBA
might think "oh, it supports largefiles by default" and therefore not
notice that the filesystem itself is not mounted with largefile
support. But I suspect that the developers would welcome autoconfig
patches if someone offered them.
A
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Andrew Sullivan 87 Mowat Avenue
Liberty RMS Toronto, Ontario Canada
<andrew@libertyrms.info> M6K 3E3
+1 416 646 3304 x110
On Monday 12 August 2002 11:30 am, Andrew Sullivan wrote: > The problem is not just a system-level one, but a filesystem-level > one. Enabling 64 bits by default might be dangerous, because a DBA > might think "oh, it supports largefiles by default" and therefore not > notice that the filesystem itself is not mounted with largefile > support. But I suspect that the developers would welcome autoconfig > patches if someone offered them. Interesting point. Before I could deploy RPMs with largefile support by default, I would have to make sure it wouldn't silently break anything. So keep discussing the issues involved, and I'll see what comes of it. I don't have an direct experience with the largefile support, and am learning as I go with this. Given that I have to make the source RPM's buildable on distributions that might not have the largefile support available, so on those distributions the support will have to be unavailable -- and the decision to build it or not to build it must be automatable. -- Lamar Owen WGCR Internet Radio 1 Peter 4:11
On Mon, Aug 12, 2002 at 11:44:24AM -0400, Lamar Owen wrote:
> > The problem is not just a system-level one, but a filesystem-level
> > one. Enabling 64 bits by default might be dangerous, because a DBA
> > might think "oh, it supports largefiles by default" and therefore not
> > notice that the filesystem itself is not mounted with largefile
> > support.
> keep discussing the issues involved, and I'll see what comes of it. I don't
> have an direct experience with the largefile support, and am learning as I go
> with this.
I do have experience with both of these cases. We're hosted in a
managed-hosting environment, and one day one of the sysadmins there
must've remounted a filesystem without largefile support. Poof! I
started getting all sorts of strange pg_dump problems. It wasn't
hard to track down, except that I was initially surprised by the
errors, since I'd just _enabled_ large file support.
This is an area that is not encountered terribly often, actually,
because postgres itself breaks its files at 1G. Most people's dump
files either don't reach the 2G limit, or they use split (a
reasonable plan).
There are, in any case, _lots_ of problems with these large files.
You not only need to make sure that pg_dump and friends can support
files bigger than 2G. You need to make sure that you can move the
files around (your file transfer commands), that you can compress the
files (how is gzip compiled? bzip2?), and even that you r backup
software takes the large file. In a few years, when all
installations are ready for this, it seems like it'd be a good idea
to turn this on by default. Right now, I think the risks are at
least as great as those incurred by telling people they need to
recompile.
A
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Andrew Sullivan 87 Mowat Avenue
Liberty RMS Toronto, Ontario Canada
<andrew@libertyrms.info> M6K 3E3
+1 416 646 3304 x110
On Mon, 2002-08-12 at 10:30, Andrew Sullivan wrote: > On Mon, Aug 12, 2002 at 10:15:46AM -0500, Greg Copeland wrote: > > > If by "turn...on", you mean recompile, that's a horrible idea IMO. > > Ah. Well, that is what I meant. Why is it horrible? PostgreSQL > doesn't take very long to compile. Many reasons. A DBA is not always the same thing as a developer (which means it's doubtful he's even going to know about needed options to pass -- if any). Using a self compiled installation may not install the same sense of reliability (I know that sounds odd) as using a distribution's package. DBA may not be a SA, which means he should probably not be compiling and installing software on a system. Furthermore, he may not even have access to do so. Means upgrading in the future may be problematic. Someone compiled with large file support. He leaves. New release comes out. Someone else upgrades and now finds things are broken. Why? If it supported it out of the box, issue is avoided. Lastly, and perhaps the most obvious, SA and DBA bodies of knowledge are fairly distinct. You should not expect a DBA to function as a SA. Furthermore, SA and developer bodies of knowledge are also fairly distinct. You shouldn't expect a SA to know what compiler options he needs to use to compile software on his system. Especially for something as obscure as large file support. > > > I guess what I'm trying to say here is, it's moving the problem from > > being a postgres specific issue (not compiled in -- having to recompile > > and install and not knowing if it's (dis)enabled) to a general body of > > knowledge (does my system support such-n-such capabilities). > > The problem is not just a system-level one, but a filesystem-level > one. Enabling 64 bits by default might be dangerous, because a DBA > might think "oh, it supports largefiles by default" and therefore not > notice that the filesystem itself is not mounted with largefile > support. But I suspect that the developers would welcome autoconfig > patches if someone offered them. The distinction you make there is minor. A SA, should know and understand the capabilities of the systems he maintains (this is true even if the SA and DBA are one). This includes filesystem capabilities. A DBA, should only care about the system requirements and trust that the SA can deliver those capabilities. If a SA says, my filesystems can support very large files, installs postgres, the DBA should expect that match support in the database is already available. Woe is his surprise when he finds out that his postgres installation can't handle it?! As for the concern for danger. Hmm...my understanding is that the result is pretty much the same thing as exceeding max file size. That is, if you attempt to read/write beyond what the filesystem can provide, you're still going to get an error. Is this really more dangerous than simply reading/writing to a file which exceeds max system capabilities? Either way, this issue exists and having large file support, seemingly, does not effect it one way or another. I guess I'm tying to say, the risk of seeing filesystem corruption or even database corruption should not be effected by the use of large file support. Please correct me if I'm wrong. Greg
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On Mon, 2002-08-12 at 11:04, Andrew Sullivan wrote: > On Mon, Aug 12, 2002 at 11:44:24AM -0400, Lamar Owen wrote: > > keep discussing the issues involved, and I'll see what comes of it. I don't > > have an direct experience with the largefile support, and am learning as I go > > with this. > > I do have experience with both of these cases. We're hosted in a > managed-hosting environment, and one day one of the sysadmins there > must've remounted a filesystem without largefile support. Poof! I > started getting all sorts of strange pg_dump problems. It wasn't > hard to track down, except that I was initially surprised by the > errors, since I'd just _enabled_ large file support. And, what if he just remounted it read only. Mistakes will happen. That doesn't come across as being a strong argument to me. Besides, it's doubtful that a filesystem is going to be remounted while it's in use. Which means, these issues are going to be secondary to actual product use of the database. That is, either the system is working correctly or it's not. If it's not, guess it's not ready for production use. Furthermore, since fs mounting, if being done properly, is almost always a matter of automation, this particular class of error should be few and very far between. Wouldn't you rather answer people with, "remount your file system", rather than, recompile with such-n-such option enabled, reinstall. Oh ya, since you're re-installing a modified version of your database, probably a good paranoid option would be to back up and dump, just to be safe. Personally, I'd rather say, "remount". > There are, in any case, _lots_ of problems with these large files. > You not only need to make sure that pg_dump and friends can support > files bigger than 2G. You need to make sure that you can move the > files around (your file transfer commands), that you can compress the > files (how is gzip compiled? bzip2?), and even that you r backup > software takes the large file. In a few years, when all > installations are ready for this, it seems like it'd be a good idea > to turn this on by default. Right now, I think the risks are at > least as great as those incurred by telling people they need to > recompile. > All of those are SA issues. Shouldn't we leave that domain of issues for a SA to deal with rather than try to force a single view down someone's throat? Which, btw, results is creating more work for those that desire this feature. Greg
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On Mon, 2002-08-12 at 16:44, Lamar Owen wrote: > Interesting point. Before I could deploy RPMs with largefile support by > default, I would have to make sure it wouldn't silently break anything. So > keep discussing the issues involved, and I'll see what comes of it. I don't > have an direct experience with the largefile support, and am learning as I go > with this. > > Given that I have to make the source RPM's buildable on distributions that > might not have the largefile support available, so on those distributions the > support will have to be unavailable -- and the decision to build it or not to > build it must be automatable. I raised the question on the Debian developers' list. As far as I can see, the general feeling is that it won't break anything but will only work with kernel 2.4. It may break with 2.0, but 2.0 is no longer provided with Debian stable, so I don't mind that. The thread starts at http://lists.debian.org/debian-devel/2002/debian-devel-200208/msg00597.html I intend to enable it in the next version of the Debian packages (which will go into the unstable archive if this works for me) by adding -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 to CFLAGS for the entire build. One person said: However compiling with largefile support will change the size of off_t from 32 bits to 64 bits - if postgres uses off_t or anything else related to file offsets in a binary struct in one of the database files you will break stuff pretty heavily. I would not compile postgres with largefile support until it is officially supported by the postgres developers. but I cannot see that off_t is used in such a way. -- Oliver Elphick Oliver.Elphick@lfix.co.uk Isle of Wight, UK http://www.lfix.co.uk/oliver GPG: 1024D/3E1D0C1C: CA12 09E0 E8D5 8870 5839 932A 614D 4C34 3E1D 0C1C ======================================== "And he spake a parable unto them to this end, that men ought always to pray, and not to faint." Luke 18:1
On Mon, Aug 12, 2002 at 11:07:51AM -0500, Greg Copeland wrote:
> Many reasons. A DBA is not always the same thing as a developer (which
> means it's doubtful he's even going to know about needed options to pass
> -- if any).
This (and the "upgrade" argument) are simply documentation issues.
If you check the FAQ_Solaris, there's already a line in there which
tells you how to do it.
> Lastly, and perhaps the most obvious, SA and DBA bodies of knowledge are
> fairly distinct. You should not expect a DBA to function as a SA.
> Furthermore, SA and developer bodies of knowledge are also fairly
> distinct. You shouldn't expect a SA to know what compiler options he
> needs to use to compile software on his system. Especially for
> something as obscure as large file support.
It seems to me that a DBA who is running a system which produces 2
Gig dump files, and who can't compile Postgres, is in for a rocky
ride. Such a person needs at least a support contract, and in such a
case the supporting organisation would be able to provide the needed
binary.
Anyway, as I said, this really seems like the sort of thing that
mostly gets done when someone sends in a patch. So if it scratches
your itch . . .
> The distinction you make there is minor. A SA, should know and
> understand the capabilities of the systems he maintains (this is true
> even if the SA and DBA are one). This includes filesystem
> capabilities. A DBA, should only care about the system requirements and
> trust that the SA can deliver those capabilities. If a SA says, my
> filesystems can support very large files, installs postgres, the DBA
> should expect that match support in the database is already available.
> Woe is his surprise when he finds out that his postgres installation
> can't handle it?!
And it seems to me the distinction you're making is an invidious one.
I am sick to death of so-called experts who want to blather on about
this or that tuning parameter of [insert big piece of software here]
without knowing the slightest thing about the basic operating
environment. A DBA has responsibility to know a fair amount about
the platform in production. A DBA who doesn't is one day going to
find out what deep water is.
> result is pretty much the same thing as exceeding max file size. That
> is, if you attempt to read/write beyond what the filesystem can provide,
> you're still going to get an error. Is this really more dangerous than
> simply reading/writing to a file which exceeds max system capabilities?
Only if you were relying on it for backups, and suddenly your backups
don't work.
A
--
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Andrew Sullivan 87 Mowat Avenue
Liberty RMS Toronto, Ontario Canada
<andrew@libertyrms.info> M6K 3E3
+1 416 646 3304 x110
On Mon, Aug 12, 2002 at 11:17:31AM -0500, Greg Copeland wrote:
>
> And, what if he just remounted it read only. Mistakes will happen.
> That doesn't come across as being a strong argument to me. Besides,
> it's doubtful that a filesystem is going to be remounted while it's in
> use. Which means, these issues are going to be secondary to actual
> product use of the database. That is, either the system is working
> correctly or it's not. If it's not, guess it's not ready for production
> use.
If it's already in production use, but was taken out briefly for
maintenance, and the supposed expert SAs do something dimwitted, then
it's broken, sure. The point I was trying to make is that the
symptoms one sees from breakage can be from many different places,
and so a glib "enable largefile support" remark hides an actual,
real-world complexity. Several steps can be broken, any one fof
which causes problems. Better to force the relevant admins to do the
work to set things up for an exotic feature, if it is desired.
There's nothing about Postgres itself that requires large file
support, so this is really a discussion about pg_dump. Using split
is more portable, in my view, and therefore preferable. You can also
use the native-compressed binary dump format, if you like one big
file. Both of those already work out of the box.
> > There are, in any case, _lots_ of problems with these large files.
> All of those are SA issues.
So is compiling the software correctly, if the distinction has any
meaning at all. When some mis-installed bit of software breaks, the
DBAs won't go running to the SAs. They'll ask here.
A
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Andrew Sullivan 87 Mowat Avenue
Liberty RMS Toronto, Ontario Canada
<andrew@libertyrms.info> M6K 3E3
+1 416 646 3304 x110
On Mon, 2002-08-12 at 11:40, Andrew Sullivan wrote: > On Mon, Aug 12, 2002 at 11:07:51AM -0500, Greg Copeland wrote: > > > Many reasons. A DBA is not always the same thing as a developer (which > > means it's doubtful he's even going to know about needed options to pass > > -- if any). > > This (and the "upgrade" argument) are simply documentation issues. > If you check the FAQ_Solaris, there's already a line in there which > tells you how to do it. And? What's you're point. That somehow make it disappear? Even if it had been documented, it doesn't mean the documentation made it to the right hands or was obviously located. Just look at postgres' documentation in general. How often are people told to "read the code". Give me a break. You're argument is a very weak straw. > > > Lastly, and perhaps the most obvious, SA and DBA bodies of knowledge are > > fairly distinct. You should not expect a DBA to function as a SA. > > Furthermore, SA and developer bodies of knowledge are also fairly > > distinct. You shouldn't expect a SA to know what compiler options he > > needs to use to compile software on his system. Especially for > > something as obscure as large file support. > > It seems to me that a DBA who is running a system which produces 2 > Gig dump files, and who can't compile Postgres, is in for a rocky > ride. Such a person needs at least a support contract, and in such a > case the supporting organisation would be able to provide the needed > binary. LOL. Managing data and compiling applications have nothing to do with each other. Try, try again. You also don't seem to understand that this isn't as simple as recompile. It's not!!!!!!!!!!! We clear on this?! It's as simple as needing to KNOW that you have to recompile and then KNOWING you have to use a serious of obtuse options when compiling. In other words, you seemingly know everything you don't know which is more than the rest of us. > Anyway, as I said, this really seems like the sort of thing that > mostly gets done when someone sends in a patch. So if it scratches > your itch . . . > > > The distinction you make there is minor. A SA, should know and > > understand the capabilities of the systems he maintains (this is true > > even if the SA and DBA are one). This includes filesystem > > capabilities. A DBA, should only care about the system requirements and > > trust that the SA can deliver those capabilities. If a SA says, my > > filesystems can support very large files, installs postgres, the DBA > > should expect that match support in the database is already available. > > Woe is his surprise when he finds out that his postgres installation > > can't handle it?! > > And it seems to me the distinction you're making is an invidious one. > I am sick to death of so-called experts who want to blather on about > this or that tuning parameter of [insert big piece of software here] > without knowing the slightest thing about the basic operating > environment. A DBA has responsibility to know a fair amount about In other words, you can't have a subject matter expert unless he is an expert on every subject? Ya, right! > the platform in production. A DBA who doesn't is one day going to > find out what deep water is. Agreed...as it relates to the database. DBA's should have to know details about the filesystem...that's the job of a SA. You seem to be under the impression that SA = DBA or somehow a DBA is an SA with extra knowledge. While this is sometimes true, I can assure you this is not always the case. This is exactly why large companies often have DBAs in one department and SA in another. Their knowledge domains tend to uniquely differ. > > > result is pretty much the same thing as exceeding max file size. That > > is, if you attempt to read/write beyond what the filesystem can provide, > > you're still going to get an error. Is this really more dangerous than > > simply reading/writing to a file which exceeds max system capabilities? > > Only if you were relying on it for backups, and suddenly your backups > don't work. > Correction. "Suddenly" your backends never worked. Seems like it would of been caught prior to going into testing. Surely you're not suggesting that people place a system into production without having testing full life cycle? Back up testing is part of your life cycle right? Greg
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On Mon, 2002-08-12 at 11:48, Andrew Sullivan wrote: > On Mon, Aug 12, 2002 at 11:17:31AM -0500, Greg Copeland wrote: [snip] > > > There are, in any case, _lots_ of problems with these large files. > > > All of those are SA issues. > > So is compiling the software correctly, if the distinction has any > meaning at all. When some mis-installed bit of software breaks, the > DBAs won't go running to the SAs. They'll ask here. Either case, they're going to ask. You can give them a simple solution or you can make them run around and pull their hair out. You're also assuming that SA = developer. I can assure you it does not. I've met many an SA who's development experience was "make" and korn scripts. Expecting that he should know to use GNU_SOURCE and BITS=64, it a pretty far reach. Furthermore, you're even expecting that he knows that such a "recompile" fix even exists. Where do you think he's going to turn? The lists. That's right. Since he's going to contact the list or review a faq item anyways, doesn't it make sense to give them the easy way out (the the initiator and the mailing list)? IMO, powerful tools seem to always be capable enough to shoot your self in the foot. Why make pay special attention with this sole feature which doesn't really address it to begin with? Would you at least agree that "--enable-large-files", rather than CFLAGS=xxx, is a good idea as might well be banners and log entries stating that large file support has or has not been compiled in? Greg
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Oliver Elphick writes:
> One person said:
> However compiling with largefile support will change the size
> of off_t from 32 bits to 64 bits - if postgres uses off_t or
> anything else related to file offsets in a binary struct in one
> of the database files you will break stuff pretty heavily. I
> would not compile postgres with largefile support until it
> is officially supported by the postgres developers.
>
> but I cannot see that off_t is used in such a way.
This is not the only issue. You really need to check all uses of off_t
(for example printf("%ld", off_t) will crash) and all places where off_t
should have been used in the first place. Furthermore you might need to
replace ftell() and fseek() by ftello() and fseeko(), especially if you
want pg_dump to support large archives.
Still, most of the configuration work is already done in Autoconf (see
AC_FUNC_FSEEKO and AC_SYS_LARGEFILE), so the work might be significantly
less than the time spent debating the merits of large files on these
lists. ;-)
--
Peter Eisentraut peter_e@gmx.net
On Mon, Aug 12, 2002 at 11:30:36AM -0400, Andrew Sullivan wrote: > The problem is not just a system-level one, but a filesystem-level > one. Enabling 64 bits by default might be dangerous, because a DBA > might think "oh, it supports largefiles by default" and therefore not > notice that the filesystem itself is not mounted with largefile > support. But I suspect that the developers would welcome autoconfig > patches if someone offered them. Are there any filesystems in common use (not including windows ones) that don't support >32-bit filesizes? Linux (ext2) I know supports by default at least to 2TB (2^32 x 512bytes), probably much more. What about the BSDs? XFS? etc -- Martijn van Oosterhout <kleptog@svana.org> http://svana.org/kleptog/ > There are 10 kinds of people in the world, those that can do binary > arithmetic and those that can't.
On Mon, 2002-08-12 at 18:41, Martijn van Oosterhout wrote: > On Mon, Aug 12, 2002 at 11:30:36AM -0400, Andrew Sullivan wrote: > > The problem is not just a system-level one, but a filesystem-level > > one. Enabling 64 bits by default might be dangerous, because a DBA > > might think "oh, it supports largefiles by default" and therefore not > > notice that the filesystem itself is not mounted with largefile > > support. But I suspect that the developers would welcome autoconfig > > patches if someone offered them. > > Are there any filesystems in common use (not including windows ones) that > don't support >32-bit filesizes? > > Linux (ext2) I know supports by default at least to 2TB (2^32 x 512bytes), > probably much more. What about the BSDs? XFS? etc > Ext2 & 3 should be okay. XFS (very sure) and JFS (reasonably sure) should also be okay...IIRC. NFS and SMB are probably problematic, but I can't see anyone really wanting to do this. Maybe some of the clustering file systems (GFS, etc) might have problems??? I'm not sure where reiserfs falls. I *think* it's not a problem but something tingles in the back of my brain that there may be problems lurking... Just for the heck of it, I did some searching. Found these for starters: http://www.suse.de/~aj/linux_lfs.html. http://www.gelato.unsw.edu.au/~peterc/lfs.html http://ftp.sas.com/standards/large.file/ So, in a nut shell, most modern (2.4.x+) x86 Linux systems should be able to handle large files. Enjoy, Greg
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Andrew Sullivan wrote: >On Sat, Aug 10, 2002 at 09:21:07AM -0500, Greg Copeland wrote: > >>I'm actually amazed that postgres isn't already using large file >>support. Especially for tools like dump. >> > >Except it would only cause confusion if you ran such a program on a >system that didn't itself have largefile support. Better to make the >admin turn all these things on on purpose, until everyone is running >64 bit systems everywhere. > >A > Ah yes ... extremely good point - I had not considered that. I am pretty sure all reasonably current (kernel >= 2.4) Linux distros support largefile out of the box - so it should be safe for them. Other operating systems where 64 bit file access can be disabled or unconfigured require more care - possibly (sigh) 2 binary RPMS with a distinctive 32 and 64 bit label ...(I think the "big O" does this for Solaris). Cheers Mark
On Tue, 2002-08-13 at 03:57, Greg Copeland wrote: > > Are there any filesystems in common use (not including windows ones) that > > don't support >32-bit filesizes? > > > > Linux (ext2) I know supports by default at least to 2TB (2^32 x 512bytes), > > probably much more. What about the BSDs? XFS? etc > > > > Ext2 & 3 should be okay. XFS (very sure) and JFS (reasonably sure) > should also be okay...IIRC. NFS and SMB are probably problematic, but I > can't see anyone really wanting to do this. Hmm. Whereas I can't see many people putting their database files on an NFS mount, I can readily see them using pg_dump to one, and pg_dump is the program where large files are really likely to be needed. -- Oliver Elphick Oliver.Elphick@lfix.co.uk Isle of Wight, UK http://www.lfix.co.uk/oliver GPG: 1024D/3E1D0C1C: CA12 09E0 E8D5 8870 5839 932A 614D 4C34 3E1D 0C1C ======================================== "Watch ye therefore, and pray always, that ye may be accounted worthy to escape all these things that shall come to pass, and to stand before the Son of man." Luke 21:36
On Mon, 2002-08-12 at 21:07, Peter Eisentraut wrote:
> This is not the only issue. You really need to check all uses of off_t
> (for example printf("%ld", off_t) will crash) and all places where off_t
> should have been used in the first place. Furthermore you might need to
> replace ftell() and fseek() by ftello() and fseeko(), especially if you
> want pg_dump to support large archives.
Searching for fseek, ftell and off_t yields only 12 files in the whole
source tree, so fortunately the impact is not enormous. As expected,
pg_dump is the main program involved.
There seem to be several places in the pg_dump code where int is used
instead of long int to receive the output of ftell(). I presume these
ought to be cleaned up as well.
Looking at how to deal with this, is the following going to be
portable?: in pg_dump/Makefile: CFLAGS += -D_LARGEFILE_SOURCE -D_OFFSET_BITS=64 in pg_dump.h: #ifdef
_LARGEFILE_SOURCE #define FSEEK fseeko #define FTELL ftello #define OFF_T_FORMAT %Ld typedef off_t
OFF_T; #else #define FSEEK fseek #define FTELL ftell #define OFF_T_FORMAT %ld typedef long int OFF_T;
#endif In pg_dump/*.c: change relevant occurrences of fseek and ftell to FSEEK and FTELL
changeall file offset parameters used or returned by fseek and ftell to OFF_T (usually from int)
constructprintf formats with OFF_T_FORMAT in appropriate places
> Still, most of the configuration work is already done in Autoconf (see
> AC_FUNC_FSEEKO and AC_SYS_LARGEFILE), so the work might be significantly
> less than the time spent debating the merits of large files on these
> lists. ;-)
Since running autoconf isn't part of a normal build, I'm not familiar
with that. Can autoconf make any of the above unnecessary?
--
Oliver Elphick Oliver.Elphick@lfix.co.uk
Isle of Wight, UK
http://www.lfix.co.uk/oliver
GPG: 1024D/3E1D0C1C: CA12 09E0 E8D5 8870 5839 932A 614D 4C34 3E1D 0C1C
======================================== "Watch ye therefore, and pray always, that ye may be accounted worthy
toescape all these things that shall come to pass, and to stand before the Son of man."
Luke 21:36
On Tue, 2002-08-13 at 03:42, Mark Kirkwood wrote: > Andrew Sullivan wrote: > > >On Sat, Aug 10, 2002 at 09:21:07AM -0500, Greg Copeland wrote: > > > >>I'm actually amazed that postgres isn't already using large file > >>support. Especially for tools like dump. > >> > > > >Except it would only cause confusion if you ran such a program on a > >system that didn't itself have largefile support. Better to make the > >admin turn all these things on on purpose, until everyone is running > >64 bit systems everywhere. > > > >A > > > Ah yes ... extremely good point - I had not considered that. > > I am pretty sure all reasonably current (kernel >= 2.4) Linux distros > support largefile out of the box - so it should be safe for them. > > Other operating systems where 64 bit file access can be disabled or > unconfigured require more care - possibly (sigh) 2 binary RPMS with a > distinctive 32 and 64 bit label ...(I think the "big O" does this for > Solaris). Then, of course, there are systems where Largefiles support is a filesystem by filesystem (read mountpoint by mountpoint) option (E.G. OpenUNIX). I think this is going to be a pandoras box. -- Larry Rosenman http://www.lerctr.org/~ler Phone: +1 972-414-9812 E-Mail: ler@lerctr.org US Mail: 1905 Steamboat Springs Drive, Garland, TX 75044-6749
On Tue, Aug 13, 2002 at 08:02:05AM -0500, Larry Rosenman wrote: > On Tue, 2002-08-13 at 03:42, Mark Kirkwood wrote: > > Other operating systems where 64 bit file access can be disabled or > > unconfigured require more care - possibly (sigh) 2 binary RPMS with a > > distinctive 32 and 64 bit label ...(I think the "big O" does this for > > Solaris). > Then, of course, there are systems where Largefiles support is a > filesystem by filesystem (read mountpoint by mountpoint) option (E.G. > OpenUNIX). > > I think this is going to be a pandoras box. I don't understand. Why would you want large-file support enabled on a per-filesystem basis? All your system programs would have to support the lowest common denomitor (ie, with large file support). Is it to make the kernel enforce a limit for the purposes of compatability? I'd suggest making it as simple as --enable-large-files and make it default in a year or two. -- Martijn van Oosterhout <kleptog@svana.org> http://svana.org/kleptog/ > There are 10 kinds of people in the world, those that can do binary > arithmetic and those that can't.
Oliver Elphick <olly@lfix.co.uk> writes:
> Looking at how to deal with this, is the following going to be
> portable?:
> #define OFF_T_FORMAT %Ld
That certainly will not be. Use INT64_FORMAT from pg_config.h.
> typedef long int OFF_T;
Why not just use off_t? In both cases?
regards, tom lane
On Tue, 2002-08-13 at 15:23, Tom Lane wrote: > > typedef long int OFF_T; > > Why not just use off_t? In both cases? The prototype for fseek() is long int; I had assumed that off_t was not defined if _LARGEFILE_SOURCE was not defined. -- Oliver Elphick Oliver.Elphick@lfix.co.uk Isle of Wight, UK http://www.lfix.co.uk/oliver GPG: 1024D/3E1D0C1C: CA12 09E0 E8D5 8870 5839 932A 614D 4C34 3E1D 0C1C ======================================== "Watch ye therefore, and pray always, that ye may be accounted worthy toescape all these things that shall come to pass, and to stand before the Son of man." Luke 21:36
Oliver Elphick <olly@lfix.co.uk> writes:
> On Tue, 2002-08-13 at 15:23, Tom Lane wrote:
>> Why not just use off_t? In both cases?
> The prototype for fseek() is long int; I had assumed that off_t was not
> defined if _LARGEFILE_SOURCE was not defined.
Oh, you're right. A quick look at HPUX shows it's the same way: ftell
returns long int, ftello returns off_t (which presumably is an alias
for long long int). Okay, OFF_T seems a reasonable answer.
regards, tom lane
Oliver Elphick wrote: > On Tue, 2002-08-13 at 03:57, Greg Copeland wrote: >>Ext2 & 3 should be okay. XFS (very sure) and JFS (reasonably sure) >>should also be okay...IIRC. NFS and SMB are probably problematic, but I >>can't see anyone really wanting to do this. > > Hmm. Whereas I can't see many people putting their database files on an > NFS mount, I can readily see them using pg_dump to one, and pg_dump is > the program where large files are really likely to be needed. I wouldn't totally discount using NFS for large databases. Believe it or not, with an Oracle database and a Network Appliance for storage, NFS is exactly what is used. We've found that we get better performance with a (properly tuned) NFS mounted NetApp volume than with attached storage on our HPUX box with several 100+GB databases. Joe
Tom Lane writes: > > The prototype for fseek() is long int; I had assumed that off_t was not > > defined if _LARGEFILE_SOURCE was not defined. All that _LARGEFILE_SOURCE does is make fseeko() and ftello() visible on some systems, but on some systems they should be available by default. > Oh, you're right. A quick look at HPUX shows it's the same way: ftell > returns long int, ftello returns off_t (which presumably is an alias > for long long int). Okay, OFF_T seems a reasonable answer. fseek() and ftell() using long int for the offset was a mistake, therefore fseeko() and ftello() were invented. (This is independent of whether the large file interface is used.) To activate the large file interface you define _FILE_OFFSET_BITS=64, which transparently replaces off_t and everything that uses it with a 64 bit version. There is no need to use any of the proposed macro tricks (because that exact macro trick is already provided by the OS). -- Peter Eisentraut peter_e@gmx.net