Qingqing Zhou wrote:
> One scenario is to use an oid to identify a toast value. As the oid
> generation is mono increased within a database instance, it can gets wrap
> around after 2^32 generations. After that:
> 1. GetNewOidWithIndex() could gets unbounded performance as it needs to by
> pass already in use values of its own.
> 2. These by-passed oids are actually usable by other toast indices, but are
> wasted. This can lead to further aggravated OID wrap around.
>
> Do we think above scenario is something we shall worry about? Especially
> for large databases.
IMO in theory it sucks that toast values use the shared OID generator,
though in practice I have never seen a problem due to that. Often,
toast value creation is interleaved across several tables, so the shared
generator does not have to skip too many values at once each time.
--
Álvaro Herrera http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
