Re: CLUSTER can change t_len
От | Greg Stark |
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Тема | Re: CLUSTER can change t_len |
Дата | |
Msg-id | AANLkTin6DiCOeyAwPKk73+cs9Zm-XG4KxhxdW3hx2zN=@mail.gmail.com обсуждение исходный текст |
Ответ на | Re: CLUSTER can change t_len (Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>) |
Ответы |
Re: CLUSTER can change t_len
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Список | pgsql-hackers |
On Tue, Nov 9, 2010 at 10:20 AM, Heikki Linnakangas <heikki.linnakangas@enterprisedb.com> wrote: >> >> We have a comment /* be conservative */ in the function, but I'm not sure >> we actually need the MAXALIGN. However, there would be almost no benefits >> to keep t_len in small value because we often treat memory in MAXALIGN >> unit. > > Hmm, the conservatism at that point affects the free space calculations. I'm > not sure if it makes any difference in practice, but I'm also not sure it > doesn't. pd_upper is always MAXALIGNed, but pd_lower is not. > > This would be more in line with what the main heap_insert code does: > Doesn't this cause assertion failures in heap_fill_tuple when the data size isn't what's expected? I guess we never actually use the t_len for later tuple reconstructions, we just recompute the needed size? -- greg
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