On Mon, 2005-04-04 at 09:48 -0400, Christopher Petrilli wrote:
> The point, in the rough middle, is where the program begins inserting
> into a new table (inherited). The X axis is the "total" number of rows
> inserted.

and you also mention the same data plotted with elapsed time:

Your graphs look identical to others I've seen, so I think we're
touching on something wider than your specific situation. The big
difference is that things seem to go back to high performance when you
switch to a new inherited table.

I'm very interested in the graphs of elapsed time for COPY 500 rows
against rows inserted. The simplistic inference from those graphs are
that if you only inserted 5 million rows into each table, rather than 10
million rows then everything would be much quicker. I hope this doesn't
work, but could you try that to see if it works? I'd like to rule out a
function of "number of rows" as an issue, or focus in on it depending
upon the results.

Q: Please can you confirm that the discontinuity on the graph at around
5000 elapsed seconds matches EXACTLY with the switch from one table to
another? That is an important point.

Q: How many data files are there for these relations? Wouldn't be two,
by any chance, when we have 10 million rows in them?

Q: What is the average row length?
About 150-160 bytes?


Best Regards, Simon Riggs

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TIP 9: the planner will ignore your desire to choose an index scan if your
      joining column's datatypes do not match

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