[OPEN-ILS-DEV] ***SPAM*** Replication-friendly default DB setup

[Brandon W. Uhlman]

Hello, all.

The database scripts Evergreen currently ships with are not  
replication-friendly for use with Slony-I, a well-known PostgreSQL  
replication tool used in larger Evergreen consortia (specifically, I  
know it is used at Georgia PINES and BC Sitka). Specifically, Slony  
stalls replication if you issue the TRUNCATE command, which is  
included in reporter schema as part of  
reporter.enable_materialized_simple_record_trigger(), and occasionally  
as part of upgrade scripts, particularly the soon-to-be-released  
1.6.0.3-1.6.0.4 upgrade script for  
money.materialized_billable_xact_summary.

For any table $foo being emptied, the best practice is to issue
   DELETE FROM {$foo};
before issuing
   TRUNCATE {$foo};

which cleans up the issue -- which has to do with TRUNCATE not being  
issued to the slave servers, and thus causing primary key collisions  
when trying to rebuild.

If there's general support for making the default configuration  
Slony-friendly, I can submit a simple patch that issues appropriate  
DELETE commands before any occurence of TRUNCATE. The downside is that  
DELETE is significantly slower than TRUNCATE for the majority of  
Evergreen libraries who do not require the scripts to be Slony-friendly.

Thoughts?

Brandon

=============================================
Brandon W. Uhlman
Lillooet, BC   V0K 1V0

brandon at branflakes.net

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