Quoting Karl Hakimian <[EMAIL PROTECTED]>:
On Fri, Feb 10, 2006 at 07:42:45PM +0100, Magnus Hagander wrote:
> Yes, it would be possible to commit the filename/path inserts
> immediately (i.e. 1 insert per transaction) but still do the
> file inserts within a larger transaction.
Not really, if you want/need to refer to them from transaction 1. If you
add them in transaction2, transaciton 1 will *never* see those rows.
It'll hav eto commit and open transactio 3 before they become visible.
This would still work if you opened a transaction for committing the
names after you finished updating paths and filenames (I'm thinking of
the case where the attributes are spooled) in a case like this, your
large number of adds to the file table will not need anything that gets
added to the path or filename table after you start.
It all depends on selected transaction isolation level (SQL standards
define four of them). PostgreSQL implements read commited level (drity
read is not possible, however non-repeatable read and phantom reads are
possible) and serializable level (dirty, non-repeatable and phantom
reads are not possible).
For proposed change to work, I guess we would need to utilize
serializable transaction isolation (the most strict level). However in
this mode, transaction might fail if any other transaction changed rows
that would result in incosisten view for the current transaction, and
Bacula would need additional code to deal with it (make appropriate
adjustments to transaction and re-attempt it).
For more info and much better description of isolation levels:
http://www.postgresql.org/docs/8.1/interactive/transaction-iso.html
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