Re: Anything to be gained from a 'Postgres Filesystem'?

lists(at)boutiquenumerique(dot)com (Pierre-Frédéric Caillaud) writes:
>> posix_fadvise(2) may be a candidate. Read/Write bareers another pone, as
>> well asn syncing a bunch of data in different files with a single call
>> (so that the OS can determine the best write order). I can also imagine
>> some interaction with the FS journalling system (to avoid duplicate
>> efforts).
>
> There is also the fact that syncing after every transaction
> could be changed to syncing every N transactions (N fixed or
> depending on the data size written by the transactions) which would
> be more efficient than the current behaviour with a sleep. HOWEVER
> suppressing the sleep() would lead to postgres returning from the
> COMMIT while it is in fact not synced, which somehow rings a huge
> alarm bell somewhere.
>
> What about read order ?
> This could be very useful for SELECT queries involving
> indexes, which in case of a non-clustered table lead to random seeks
> in the table.

Another thing that would be valuable would be to have some way to say:

"Read this data; don't bother throwing other data out of the cache
to stuff this in."

Something like a "read_uncached()" call...

That would mean that a seq scan or a vacuum wouldn't force useful data
out of cache.
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