On 12/6/05, Hannu Krosing wrote:
>
> 1) run a transaction repeatedly, trying to hit a point of no concurrent
> transactions, encance the odds by locking out starting other
> transactions for a few (tenths or hundredths of) seconds, if it
> succeeds, record SNAP1, commit and and continue, else rollback, then
> sleep a little and retry.
Which locks can be released by committing here?
> 2) build index on all rows inserted before SNAP1
>
> 3) run a transaction repeatedly, trying to hit a point of no concurrent
> transactions by locking out other transactions for a few (tenths or
> hundredths of) seconds, if it succeeds, record SNAP2, mark index as
> visible for inserts, commit. now all new transactions see the index and
> use it when inserting new tuples.
>
> 4) scan over table, add all tuples between SNAP1 and SNAP2 to index
You can not guarantee that every tuple inserted in the table will be
visible to SNAP 2 if you take SNAP2 before the commit of the
insert-only index has dropped below the global XMIN-horizon.
> 5) mark index as usable for query plans
How about:
- begin transaction X1 - insert all visible tuples in an index - mark index incomplete
- commit
- wait for X1 to become visible to all running transactions (X1 is
known from the XMIN in pg_class / pg_index)
- begin transaction X2 - insert all missing tuples in index - mark index complete
- commit
Jochem
