Re: Transaction isolation

Gerhard Häring pisze:
> Pawel Lewicki wrote:
>> Hi,
>> I tried using
>>
>> con = sqlite.connect(..., isolation_level=None)
>>
>> but inserting is incredibly slow and making hard drive busy.
> 
> Sure. You're working in autocommit mode then. That means every DML 
> (insert, update, delete, replace) works in its own transaction, and 
> after each command, the database engine has to flush the cache to disk. 
> That of course is slow.
> 
> Using pysqlite as it's meant to be used and calling the connection's 
> commit() method whenever you have consistent data is recommended.
> 
> If you do mass inserts for importing data, you can make your code faster 
> if you commit only every 1000 inserts or so.
> 
> If after all possible optimizations (not too many commits, using 
> prepared statements, etc.) you still *really need* to improve 
> performance of bulk imports, reading
> 
> http://www.sqlite.org/pragma.html
> 
> and turning on PRAGMA synchronous = OFF;
> 
> This implies the risk of data corruption should a power failure happen, 
> but for initial imports this is IMO worth it.
> 
> -- Gerhard

OK,
But performance is not a problem in my case. I have a series of SQL 
queries I want to perform in one transaction.
- remove all data form a table
- reload new snapshot
I see that between these commands (forced delay) query from second 
connection (ODBC) returns an empty set. That's all. All trickery with 
'begin;end;' was a result of my searching.


Paweł Lewicki

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