Mon Aug 16 19:58:23 PDT 2004
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Log Message: ----------- Added another idiosyncracy, namely that you can't have two subscribers loading data at the same time. Modified Files: -------------- slony1-engine/doc/howto: helpitsbroken.txt (r1.1 -> r1.2) -------------- next part -------------- Index: helpitsbroken.txt =================================================================== RCS file: /usr/local/cvsroot/slony1/slony1-engine/doc/howto/helpitsbroken.txt,v retrieving revision 1.1 retrieving revision 1.2 diff -Ldoc/howto/helpitsbroken.txt -Ldoc/howto/helpitsbroken.txt -u -w -r1.1 -r1.2 --- doc/howto/helpitsbroken.txt +++ doc/howto/helpitsbroken.txt @@ -7,7 +7,7 @@ Here are some things other people have stumbled over that might help you to "stumble more quickly." -1. I looked for the _clustername namespace, and it wasn't there! +1. I looked for the _clustername namespace, and it wasn't there. If the DSNs are wrong, then slon instances can't connect to the nodes. @@ -92,3 +92,43 @@ If you have key = 'nspace.key_on_whatever' the request will FAIL. + +8. I'm trying to get a slave subscribed, and get the following +messages in the logs: + +DEBUG1 copy_set 1 +DEBUG1 remoteWorkerThread_1: connected to provider DB +WARN remoteWorkerThread_1: transactions earlier than XID 127314958 are still in progress +WARN remoteWorkerThread_1: data copy for set 1 failed - sleep 60 seconds + +Oops. What I forgot to mention, as well, was that I was trying to add +TWO subscribers, concurrently. + +That doesn't work out: Slony-I won't work on the COPY commands +concurrently. See src/slon/remote_worker.c, function copy_set() + +This has the (perhaps unfortunate) implication that you cannot +populate two slaves concurrently. You have to subscribe one to the +set, and only once it has completed setting up the subscription +(copying table contents and such) can the second subscriber start +setting up the subscription. + +It could also be possible for there to be an old outstanding +transaction blocking Slony-I from processing the sync. You might want +to take a look at pg_locks to see what's up: + + +sampledb=# select * from pg_locks where transaction is not null order by transaction; + relation | database | transaction | pid | mode | granted +----------+----------+-------------+---------+---------------+--------- + | | 127314921 | 2605100 | ExclusiveLock | t + | | 127326504 | 5660904 | ExclusiveLock | t +(2 rows) + +See? 127314921 is indeed older than 127314958, and it's still running. + +$ ps -aef | egrep '[2]605100' +postgres 2605100 205018 0 18:53:43 pts/3 3:13 postgres: postgres sampledb localhost COPY + +This happens to be a COPY transaction involved in setting up the +subscription for one of the nodes.
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