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Brad Hilton wrote:
| hannu at skype.net wrote:
|
|>> Hello,
|>>
|>> I've spent the last few days learning slony and setting it up on some
|>> test databases with good results.  However, when I set up replication on
|>> my live database, the slon processes startup and appear to be preparing
|>> to copy things over when I get:
|>>
|>> "The postmaster has commanded this server process to roll back the
|>> current transaction and exit, because another server process exited
|>> abnormally and possibly corrupted shared memory."
|>>
|>> This happens continually until I uninstall the slony schema from my
|>> database.
|>
|> Does slon  need to be running or is it happening even without it
|> (maybe as
|> a result of slony triggers doing something bad) ?
|
| No, slon does not need to be running for the crashes to occur.

That's useful to know; that suggests that the reason for the problem may
not directly relate to Slony-I.

You should consider the possibility that there is some independent
problem that is the _real_ thing that needs to be found.  It would be
unfortunate to direct your attentions all at Slony-I, only to discover
that the real problem is something else.

We ran into that recently in the context of performance; there was a
system behaving strangely, and at "first blush," all fingers were
pointing at Slony-I as the thing that had been most recently introduced.
~ Ultimately, the investigations found that there was a
bug/misconfiguration in a hardware monitoring process that was related
only insomuch as it caused wacky I/O patterns that made COMMITs run
slowly, which particularly injured certain Slony-I transactions :-(.

The point is that you need to have a pretty high degree of skepticism as
to what is the actual cause.  Symptoms != Causes.  Unfortunately, the
more components you glue together, the more things there are that can
cause "bad things." :-(

| I'll work on getting a stack trace.

That should be helpful.
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