On 02-04-2015 AM 09:24, Jim Nasby wrote:
> The other potential advantage (and I have to think this could be a BIG
> advantage) is extending by a large amount makes it more likely you'll get
> contiguous blocks on the storage. That's going to make a big difference for
> SeqScan speed. It'd be interesting if someone with access to some real systems
> could test that. In particular, seqscan of a possibly fragmented table vs one
> of the same size but created at once. For extra credit, compare to dd bs=8192
> of a file of the same size as the overall table.
>
Orthogonal to topic of the thread but this comment made me recall a proposal
couple years ago[0] to add (posix_)fallocate to mdextend(). Wonder if it helps
the case?
Amit
[0]
http://www.postgresql.org/message-id/CADupcHW1POmSuNoNMdVaWLTq-a3X_A3ZQMuSjHs4rCexiPgxAQ@mail.gmail.com
