>> 1. As known, an InMemory-DB is currently not (much) faster
>> than working against a File.
>> With the new VFS I think, that much faster InMemory-
>> DB-Handling should be possible, is that right?
> I don't think so. The vfs is really an interface for moving
> data (pages) in and out of the pager cache.
Yep, so I understood them.
> The way in-memory databases currently work, pages are
> just kept in the page-cache all the time and never written
> out to whatever system implements the vfs interface.
Ah, ok.
Somehow thought, that the InMemory-Handling was implemented,
working against the b-trees, but then going *through*
a "non-sized" pager-cache against "something behind it",
wich was implemented using standard-fileio-apis, working
against memory-mapped-files (so being system-dependent
and not so performant like a "real selfwritten Filesystem").
>From my Insert-Tests (50,000 records on 6 mixed Columns):
Filebased (sync=off, pagesize 4kB): ca. 0.7sec
InMemory (pagesize 4kB): ca. 0.55sec
(all done using direct bindings on the same Insert-statement)
So it seems, that *not* seeing a huge performance-boost
is more, because most of the "insert-time" is spent populating
the B-tree, right?
Anyway, an easy to use, already built in "Dump-Interface"
for InMemory-DBs (able to be initialized with a given Byte-
Content) would be nice. ;-)
(Yes, I saw patches for this ask, but some time ago, not
knowing if those work with the current pager. Simply thought,
that this is a good time, to ask for an "officially supported"
interface-enhancement regarding this functionality, mainly
because of the new VFS and because I thought, you would
use its capabilities in either way for InMemory-DBs).
Regards,
Olaf Schmidt
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