On 19 Oct 2018, at 5:55am, Yuri <[email protected]> wrote:
> I noticed that my DB import process is much slower when run on the DB on
> disk, vs. in memory. It reads files and runs a massive amount of
> inserts/updates.
Memory access is much faster than disk access. If you're using actual spinning
hard disks, your computer has to wait for the disk to be spun to the right
place before it can read or write data. That could take 1/5000th of a second.
By contrast, memory access is almost instant.
> Why is this? Is there any way to speed it with disk without using in-memory
> DB?
If you are importing into an empty database and you don't care about corruption
due to power-failure, it would be safe to do
PRAGMA synchronous = OFF;
PRAGMA journal_mode = OFF;
before the import. If you do this, make sure you close the file after the
import. When it is reopened these settings will have been reset to the
default. For an explanation of what these do, see
<https://sqlite.org/pragma.html>
Simon.
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