On 8/22/2007 8:32 PM, Radim Kolar SF.NET wrote:
> small changes to slony can improve
> performance a lot during replicating over wan high-latency link.
> 
> 1. fetch more than 100 lines at once becase fetching over WAN is slow
>   its easy to compute average line size and then fetch for example +- 1MB
>   of log lines. 
> 
> 2. Can pgsql use gzip compression for data transfers?

I made good experiences with compressed ssh port forwarding.

> not related to wan but
> 3. consider to use prepared statements for updating subscribed tables

The problem with prepared statements is that any given log entry might 
touch different columns in the table. So for a table with 8 columns 
there are 255 different possible prepared statements to keep around. In 
reality, an application might show a certain pattern of 4-10 different 
updates per table, but keeping a cache and detecting which statement to 
use when isn't as easy to implement as it is to say "use prepared 
statements".

An idea I had for a future "thing" is to feed the replication log via 
COPY into the replica and have a trigger on that log table interpret it 
and do all the table modifications.


Jan

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