On 7/2/07, Jan Wieck <[EMAIL PROTECTED]> wrote:
The stuff I am currently (very slowly) working on is that very problem.
Any long running transaction causes that the minxid in the SYNC's is
stuck at that very xid during the entire runtime of the LRT. The problem
with that is that the log selection in the slon worker uses an index
scan who's only index scankey candidates are the minxid of one and the
maxxid of another snapshot. That is the range of rows returned by the
scan itself. Since the minxid is stuck, it will select larger and larger
groups of log tuples only to filter out most of them on a higher level
in the query via xxid_le_snapshot().

How the LRT problem is avoided in PGQ:

http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/skytools/skytools/sql/pgq/functions/pgq.batch_event_sql.sql?rev=1.2&content-type=text/x-cvsweb-markup

Basic idea is that there are only few LRT's, so its reasonable
to pick up bottom half of range by event txid, one-by-one.

--
marko
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