Re: Reduce the size of PageFreeSpaceInfo on 64bit platform

I wrote:

> I'll rewrite my patch to use
> FSMPageData in both places so that users can always estimate the memory
> to 6 bytes per page.

Here is a revised patch to reduce memory usage during VACUUM,
using FSMPageData (6 byte) instead of PageFreeSpaceInfo (8 or 16 bytes).
The keepable pages with freespace will extended to 21GB from 8GB with
16MB of default maintenance_work_mem.

Regards,
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ITAGAKI Takahiro
NTT Open Source Software Center