Re: [SPAM] Re: WAL directory size calculation - Mailing list pgsql-general

The question to ask is what benefit would you gain by saving BLOB object on a database than on say a flat file server or url on an ftp server? Specially larger ones.

BLOB’s cause a lot problem for all DBs. Not unless the DB engine can understand their structure and process them. It is not worth the effort.

It can hit the DB performance in Indexing, backups, migrations and load balancing.  

Hope this helps.

 

Aside of this, I'm having 350 DBs that sum up a bit more than 1 TB, and plan
to use wal_level=archive because I plan to have a backup server with barman.

 

With that many databases with that so many objects

350 DBs with about 130 tables and a bunch of sequences each, for the sake of precision.
With extensive use of BLOBs.

and undoubtable client connections,

Yes, that's another big problem... we run normally between 500 and 700 concurrent connections... I had to set max_connections=1000, the whole thing grew up faster than we were prepared for...

I'd want to spread that across a cluster of smaller servers.

That will be step 2... while migration is running (and will run for some months, we have to plan migration with users) I'll test putting another one or two machines in cluster, make some test cases, and when ready, databases will be migrated on other machines, too.
I posted a question about this some months ago, and I was told that one solution would be to set the servers to be master on some databases and slave on others, so we can have a better load balancing (instead of having all writes on the sole master, we split among all masters depending on which database is getting the write command, especially when having to write BLOBs that can be some megabytes in size).
I don't know to achieve this, but I will find a way somewhere.

just sayin...

ideas are always precious and welcome.

 

-- 

john r pierce, recycling bits in santa cruz