Re: Fwd: [GENERAL] 4B row limit for CLOB tables

From: José Luis Tallón <jltallon(at)adv-solutions(dot)net>
To: pgsql-hackers(at)postgresql(dot)org
Cc: Stephen Frost <sfrost(at)snowman(dot)net>, Jim Nasby <Jim(dot)Nasby(at)BlueTreble(dot)com>, 'Bruce Momjian' <bruce(at)momjian(dot)us>
Subject: Re: Fwd: [GENERAL] 4B row limit for CLOB tables
Date: 2015-04-28 10:41:26
Message-ID: 553F63D6.3060507@adv-solutions.net
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On 04/27/2015 08:49 AM, Jim Nasby wrote:
> On 4/25/15 1:19 PM, Bruce Momjian wrote:
>> Note if you are storing a table with rows that exceed 2KB in size
>> (aggregate size of each row) then the "Maximum number of rows in a
>> table" may be limited to 4 Billion, see TOAST.
>
> That's not accurate though; you could be limited to far less than 4B
> rows. If each row has 10 fields that toast, you'd be limited to just
> 400M rows.

ISTM like the solution is almost here, and could be done without too
much (additional) work:
* We have already discussed having a page-per-sequence with the new
SeqAMs being introduced and how that would improve scalability.
* We have commented on having a sequence per TOAST table
(hence, 4B toasted values per table each up to 4B chunks in size...
vs just 4B toasted values per cluster)

I'm not sure that I can do it all by myself just yet, but I sure
can try if there is interest.
(just after I'm done with another patch that is independent from
this, though)

This would be material for 9.6, of course :)

Thanks,

J.L.

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