wyx6fox@sina.com wrote:
> after shaming , I think i should pick out some my points:
> the unique constraints actualy kill concurrency write transaction when
> concurrency insert violate the unique constraints , they block each
> other , i test this in oracle10g, has the same behavour. I think this
> may be reasonable because the uqniue check must be the seriazable check .
> for resolve this problem , i do the unique check in application as
> possible , but in big concurrency env , this is not good way .
>
How can you enforce uniqueness in the application? If you implement it
correctly, you need considerably longer than letting it do PostgreSQL.
Even if you use some kind of magic, I could not imagine, how you can
implement a unique constraint in the application and gaurantee
uniqueness while at the same time be faster than the RDBMS.
Leo