Re: [HACKERS] Re: Are large objects well supported? Are they considered very stableto use?

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От Tatsuo Ishii
Тема Re: [HACKERS] Re: Are large objects well supported? Are they considered very stableto use?
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Msg-id 199903301358.WAA01380@ext16.sra.co.jp
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Ответ на Re: Are large objects well supported? Are they considered very stableto use?  (Chris Bitmead <chris.bitmead@bigfoot.com>)
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> > I have tried to use the lo interface and it appears to
> > work ok (although there is a fix required for solaris).
> > There is also a memory leak in the back end so several
> > thousand large objects will probably cause the backend
> > to fail .

This was reported some times ago but I don't have time to fix.

> Ouch.
> 
> Well perhaps if I tell you PG hackers what I want to do, if you could
> tell me the best way to do it.
> 
> I want to have a comment database storying ascii text comments. These
> could be over 8000 bytes, and my understanding is that conventional PG
> rows can't be bigger than 8000 bytes. On the other hand most of them
> will probably be much smaller than 8000 bytes. I will certainly have
> more than "several thousand" of them.

I thought the problem stated above was in that creating lots of large
objects in a session could be a trouble. On the other hand, if you
read/or write not so much in a session, you could avoid the problem, I
guess.

> Is large objects the right way to go here? What are the disk usage /
> speed tradeoffs of using large objects here, perhaps compared to
> straight UNIX files? The main reasons I don't use the file system is
> that I might run out of inodes, and also it's probably not that fast or
> efficient.

If you are short of inodes, forget about large objects. Creating a
large object consumes 2 inodes (one is for holding data itself,
another is for an index for faster access) and problably this is not
good news for you.

I think we could implement large objects in a different way, for
example packing many of them into a single table. This is just a
thought, though.
---
Tatsuo Ishii


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