Re: pg_dump object sorting

Tom Lane wrote:
> Andrew Dunstan <andrew@dunslane.net> writes:
>   
>> I should have expressed it better. The idea is to have pg_dump emit the 
>> objects in an order that allows the restore to take advantage of sync 
>> scans. So sync scans being disabled in pg_dump would not at all matter.
>>     
>
> Unless you do something to explicitly parallelize the operations,
> how will a different ordering improve matters?
>
> I thought we had a paper design for this, and it involved teaching
> pg_restore how to use multiple connections.  In that context it's
> entirely up to pg_restore to manage the ordering and ensure dependencies
> are met.  So I'm not seeing how it helps to have a different sort rule
> at pg_dump time --- it won't really make pg_restore's task any easier.
>
>             
>   

Well, what actually got me going on this initially was that I got 
annoyed by having indexes not grouped by table when I dumped out the 
schema of a database, because it seemed a bit illogical. Then I started 
thinking about it and it seemed to me that even without synchronised 
scanning or parallel restoration, we might benefit from building all the 
indexes of a given table together, especially if the whole table could 
fit in either our cache or the OS cache.

cheers

andrew