Is it more CPU-efficient to read/write config file or read/write sqlite database?
rosuav at gmail.com
Wed Dec 18 04:35:51 CET 2013
On Wed, Dec 18, 2013 at 1:37 PM, Cameron Simpson <cs at zip.com.au> wrote:
>> I'd say this is the right thing for a DB to do. If it comes back
>> from a commit() call, it better be on that disk, barring a failure
>> of the physical hardware. If it comes back from a commit() and data
>> gets lost because of a power-failure, something is wrong.
> Depends on your view. People seem to treat dbs as some special form
> of data storage. I don't; to me they're no different to storing
> data in any other file. Do you do an fsync() every time you close
> a file you've written? Of course not, it is a gratuitous performance
> loss. IMO, I've handed the data to the filesystem layer; its
> integrity is now the OS's problem.
An SQL database *is* a different form of storage. It's storing tabular
data, not a stream of bytes in a file. You're supposed to be able to
treat it as an efficient way to locate a particular tuple based on a
set of rules, not a different way to format a file on the disk. If you
want file semantics, use a file. Otherwise, what do you expect
commit() to do?
Also: the filesystem layer doesn't guarantee integrity. If you don't
fsync() or fdatasync() or some other equivalent , it's not on the
disk yet, so you can't trust it.
 See eg the PostgreSQL info on the subject:
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