mnavahan wrote:
> now can help me for below :
>
> what mean in PG "databse crash" can i crash db without any hardware problem
> and disk over (in not av !) ?
> (linux or win )
Like any software, PostgreSQL has bugs (though once identified, they
don't seem to last long). Crash bugs are rare, though, and if you do
manage to crash the backend that's running a query, usually all that
happens is that the client loses its connection and the transaction is
rolled back.
PostgreSQL has to be pretty robust in the face of backend crashes,.
Buggy C extensions could crash a backend pretty easily. The postmaster
has to be able to identify and clean up after a crashed backend,
ensuring there's no damage to the on-disk tables, indexes, etc.
As for an online reindex: You shouldn't need to in the first place;
index corruption shouldn't happen. However, there are other reasons you
might want to reindex, like if you have certain unusual query patterns
that tend to bloat indexes. Anyway ... you can reindex a table without
affecting queries that don't touch that table. Queries that do touch the
table will be blocked. There isn't currently any REINDEX CONCURRENTLY
option, but people seem to have a few workarounds that do the job if you
really do need to rebuild an index on a live, active table.
You should really never need to shut PostgreSQL down to do admin work.
You might need to do work that locks a few tables for a while, but
you'll rarely affect other tables and unrelated queries.
--
Craig Ringer
