Jeff Davis wrote:
> On Tue, 2007-07-03 at 12:33 -0400, Christopher Browne wrote:
>   
>> I'll see about doing an experiment on this to see if, for the DELETE
>> case, it seems to actually help.  It may be that the performance
>> effects are small to none, so that the added code complication isn't
>> worthwhile.
>>
>>     
>
> In a simple test I ran, DELETE of the entire 5M record table using
> sequential scan was MUCH faster (9.41s) than 5M individual DELETE
> statements in a single transaction (552.49s).
>
>   
>   
I have a test running here...

cbbrowne at dba2:~/records/2007/2007-07-03> for i in *log; do
for> echo $i
for> echo "-------------------------------------------------------"
for> cat $i
for> echo "======================================================="
for> done
hundreds.log
-------------------------------------------------------
Started
Tue Jul  3 22:03:16 UTC 2007
=======================================================
onedelete.log
-------------------------------------------------------
Started
Tue Jul  3 21:57:04 UTC 2007
Started purging by onedelete
Tue Jul  3 21:58:41 UTC 2007
Completed deletions
Tue Jul  3 21:59:24 UTC 2007
=======================================================
thousands.log
-------------------------------------------------------
Started
Tue Jul  3 21:47:07 UTC 2007
Started purging by thousands
Tue Jul  3 21:47:22 UTC 2007
Completed deletions
Tue Jul  3 21:53:12 UTC 2007
=======================================================


My PC is evidently slower than yours; it took ~43s for the "one big delete"

Doing it in groups of 1K took 4:50 (e.g. - 4 minutes 50 seconds)

I'll be running against groups of 100 and against groups of 1 overnight; 
presumably both will be worse than my other numbers.  It'll be 
interesting to see how much worse than 4:50 it gets...