On 20 Feb 2013, at 3:59, Clemens Ladisch wrote:
Seebs wrote:
I tried ... an in-memory database.
What I observed was a very, very, large slowdown.
We're talking 10MB of database
That database would be in the OS's file cache anyway.
It should. Problem is, there's a nearby program that was doing fsync()
operations on something else, and the filesystem's implementation is
such that an fsync on ANY file is a complete disk flush for everybody.
So avoiding any writes to the filesystem is really important even with
synchronous = OFF.
3. It is dramatically reduced in degree by pragma page_size = 8192.
The default cache size is measured in pages.
So maybe your cache size is too small?
Well, that's sort of the question: Should cache size be relevant for a
:memory: db?
Could you show some example query?
What is the EXPLAIN QUERY PLAN output?
All the queries are completely trivial. "SELECT * FROM files WHERE path
= '...';" type stuff. They match indexes. And again, this is all
performance problems *compared to writing to a disk*.
-s
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