On 1/7/20 12:58 PM, Israel Brewster wrote:
On Jan 7, 2020, at 11:56 AM, Alan Hodgson <ahodgson@xxxxxxxxxxxxxxx> wrote:
On Tue, 2020-01-07 at 11:47 -0900, Israel Brewster wrote:
One potential issue I just thought of with this approach: disk space.
Will I be doubling the amount of space used while both tables exist?
If so, that would prevent this from working - I don’t have that much
space available at the moment.
The original update you planned would do that, too.
You probably need to just do the update in batches and vacuum the table
between batches.
Really? Why? With the update I am only changing data - I’m not adding any additional data, so the total size should stay the same, right? I’m obviously missing something… :-)
https://www.postgresql.org/docs/12/sql-vacuum.html
"VACUUM reclaims storage occupied by dead tuples. In normal PostgreSQL
operation, tuples that are deleted or obsoleted by an update are not
physically removed from their table; they remain present until a VACUUM
is done. Therefore it's necessary to do VACUUM periodically, especially
on frequently-updated tables."
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Israel Brewster
Software Engineer
Alaska Volcano Observatory
Geophysical Institute - UAF
2156 Koyukuk Drive
Fairbanks AK 99775-7320
Work: 907-474-5172
cell: 907-328-9145
--
Adrian Klaver
adrian.klaver@xxxxxxxxxxx
