Re: Remove xmin and cmin from frozen tuples

Alvaro,

> What issues did he raise on this?

On having no Xmin.

> What I'm saying is that you can write a heap file, on which the tuples
> would all have xmin=FrozenTransactionId, xmax=Invalid, and the
> corresponding bits set in the infomask. This ensures that no matter the
> state of the server, you can plug the file in and all tuples will be
> valid.
>
> The "only" problem is figuring out how to lay the data in the tuples
> themselves, w.r.t endianness and such. This is platform-dependent, so
> you have to write code to do it correctly. In absence of user-defined
> types, this should not be _too_ hard to do. Of course, such a program
> would in general also be Postgres-version-dependent.

So, bulk loading by file generation? So the idea is that you would generate
a properly formatted PostgreSQL table file, and then in one transaction
create the table and attach it?

Seems like this would have the additional limitation of being useful only for
loading new partitions/new tables. However, it would have some significant
advantages for bulk loading ... chiefly that the data page generation and
associated computations could be done *off* the database server. This might
help considerably in getting around the 100mb/s data computation ceiling
we're hitting ...

--
Josh Berkus
Aglio Database Solutions
San Francisco