Re: Q about transactions

Hi Again, I thought about it a while and I still filling somewhat vague.

If in one transaction I start Serial mode and the other I start later in
Read Committed mode, what will happen if the Serializable transaction will
change some of the rows that the Read Committed is relay on ?

Thanks in Advance.

> "Ben-Nes Michael" <miki(at)canaan(dot)co(dot)il> writes:
> > When I want to insert a branch to the tree I need:
> > 1. select lft, rgt from the table to find where to insert
> > 2. using update I open a gap in the tree ( offset all the lft, rgt above
the
> > location by two )
> > 3. using insert I add a new branch.
>
> > so "select for updates" seem inappropriate as I select only one row as I
> > understood it lock only this row.
> > Read Committed is also bad as if the second transaction will use select
> > before the first transaction ran the update the select will be useless.
> > so it seems that Serializable isolation is the solution, or am I wrong ?
>
> Yeah. Use serializable mode, and be prepared to cope with "can't
> serialize" errors (a retry loop around the whole transaction is the
> standard answer to that).
>
> regards, tom lane
>
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