Re: Why could different data in a table be processed with different performance?
| От | Vladimir Ryabtsev |
|---|---|
| Тема | Re: Why could different data in a table be processed with different performance? |
| Дата | |
| Msg-id | CAMqTPqkYs+sfikTkzDuBd8yXX7+pMThW1ErfBYzw-yLRT=9Y7Q@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: Why could different data in a table be processed with differentperformance? (Fabio Pardi <f.pardi@portavita.eu>) |
| Ответы |
Re: Why could different data in a table be processed with differentperformance?
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| Список | pgsql-performance |
> You will have lesser
> slots in the cache, but the total available cache will indeed be> unchanged (half the blocks of double the size).
But we have many other tables, queries to which may suffer from smaller number of blocks in buffer cache.
> To change block size is a
> painful thing, because IIRC you do that at db initialization time
> painful thing, because IIRC you do that at db initialization time
My research shows that I can only change it in compile time.
And then initdb a new cluster...
Moreover, this table/schema is not the only in the database, there is a bunch of other schemas. And we will need to dump-restore everything... So this is super-painful.
> It could affect space storage, for the smaller blocks.
But at which extent? As I understand it is not something about "alignment" to block size for rows? Is it only low-level IO thing with datafiles?
> But before going through all this, I would first try to reload the data
> with dump+restore into a new machine, and see how it behaves.Yes, this is the plan, I'll be back once I find enough disk space for my further experiments.
Vlad
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