Christian Michel at amplix christianm
Fri Jan 7 16:41:48 PST 2005
Hello,

to replicate the databases of the company, where I work,
I decided to use slony-I.

I created a Perl-script to manage creation of database,replicationset
and some other functionalities

Following processes works fine:
- creating/init cluster und store nodes
- subscription of nodes
- unsubscribing nodes

Following processes works, but create some errors:
a) complete deletion of replicationdata (unsubscribe, drop set, drop
node etc.) -->
after unsubscribing the nodes, the are transaction, which have to be
written to the slony-tables, but "drop set" and "drop node" are reacts
to fast, so the transaction won't be written anymore and an error
raised up, that the replication-schema did not exists.
So, how can I prevent this error?
All the commands are located in 1 slonik-commandline. Should I decide
to stop (unsubscribe) and later (1 minute or so) to drop the
replication?

b) one of our databases, which is in "replication-mode", needs a
schema-update (user has recognized that a field with varchar(200) was
to short)
I created a SQL-File, which do the following:
creates a copy of the table
ALTER table RENAME tablefield TO tablefield_old;
ALTER table ADD COLUMN tablefield text;
UPDATE table SET tablefield = copytable.tablefield WHERE table.primkey
= copytable.primkey
ALTER TABLE table DROP COLUMN tablefield_old

The SQL-Statements are called after an unsubscribe node();
After the SQL-statements a subscribe node () is called.

The schema-update works fine, but slony-Log offers an error, that
COPY fails, because the table-structure didn't fit the content of COPY
anymore.

Documentation about these special things is very limited and I
couldn't find examples about these steps.

So, can anyone help me, to solve these problems?

Thanks a lot

Regards
Christian Michel




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