Re: toast by chunk-end (was Re: PG_PAGE_LAYOUT_VERSION 5 - time for change)

Alvaro Herrera napsal(a):
> Zdenek Kotala wrote:
>> Alvaro Herrera napsal(a):
>>> Heikki Linnakangas wrote:
>>>
>>>> Hmm, you're right. I think it can be made to work by storing the
>>>> *end* offset of each chunk. To find the chunk containing offset X,
>>>> search for the first chunk with end_offset > X.
>>> FWIW I'm trying to do this. So far I've managed to make the basic thing
>>> work, and I'm about to have a look at the slice interface.
>
> Okay, so this seems to work. It's missing writing the sanity checks on
> the returned data, and a look at the SGML docs to see if anything needs
> updating. I'm also going to recheck code comments that may need
> updates.
>
>

Hi Alvaro,

Just a very quick look on your patch. See my comments:

1) TOAST_MAX_CHUNK_SIZE should be removed from controldata structure.

2) PG_PAGE_LAYOUT_VERSION should be bump

3) the other main idea of toast redesign has been to add colnum information to
each chunk.

If I'm thinking more about it, it solves one problem but add another - index
update when page layout is converted during a read. And there are another issues
which we need to solve - I will send new mail.

Zdenek