Hi,
I have a table with 15M rows. Table is around 5GB on disk.
Clustering the table takes 5 minutes.
A seq scan takes 20 seconds.
I guess clustering is done using a seq scan on the index and then fetching the
proper rows in the heap.
If that's the case, fetching random rows on disk is the
On Thu, Aug 20, 2009 at 8:28 AM, Scara Maccaim_li...@yahoo.it wrote:
Hi,
I have a table with 15M rows. Table is around 5GB on disk.
Clustering the table takes 5 minutes.
A seq scan takes 20 seconds.
I guess clustering is done using a seq scan on the index and then fetching
the proper
I've found it easier to select everything into another
table, truncate
the original table, then insert the rows as:
that takes 50 seconds of pure sorting and 8GB of ram to sort; my method doesn't
require more memory than the size of the heap table, and no sorting, since the
index is already
Scara Maccai wrote:
I mean: there's access exclusive lock on the table while clustering,
so I don't see any problem in doing it... this way you could
- avoid sorting (which is what is used in the method create newtable
as select * from oldtable order by mycol, and can be slow with 15M
There was an
attempt to fix it (for example so that it could try to do a
seqscan+sort
instead of indexscan), but it stalled.
Actually I read that, but it's complicated... it involves planning and a lot of
other stuff I don't even know about...
My solution I guess would be easier (but, of
