Re: Moving a large DB (> 500GB) to another DB with different locale

På tirsdag 12. januar 2016 kl. 23:28:55, skrev Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us
<mailto:tgl(at)sss(dot)pgh(dot)pa(dot)us>>:
Andreas Joseph Krogh <andreas(at)visena(dot)com> writes:
> P�� tirsdag 12. januar 2016 kl. 22:56:56, skrev John R Pierce <
> pierce(at)hogranch(dot)com <mailto:pierce(at)hogranch(dot)com>>:
>> On 1/12/2016 1:20 PM, Andreas Joseph Krogh wrote:
>>> I'm moving a > 500GB DB to another server which is initdb'ed with a
>>> different locale (nb_NO.UTF-8 to get correct collation when ORDER BY).
>>> Is there another option than pg_dump/restore for doing this?

>>  nope, because the text data has to be converted to the new encoding,
>>  indexes rebuilt since the collation order is different, etc.

> I was pretty sure there wasn't, but had to ask before imposing downtime on
our
> customers.

If you're only changing collation and not encoding, then in principle you
could move the tables over and then reindex each collation-sensitive
index.  pg_upgrade has no ability to do that for you though, which would
make it an error-prone manual process.  Also, it'd be far from
zero-downtime since you still gotta rebuild a lot of indexes.

regards, tom lane
 
This is interessting.
I'm only changin collation, the encoding (UTF-8) is the same. I'm replacing
the packaged PG's version of initdb (resulting in en_US.UTF-8) with:
/usr/lib/postgresql/9.5/bin/initdb --locale=nb_NO.UTF-8 -D
/var/lib/postgresql/9.5/main
 
Are you saying that I don't have to re-initdb and can just change collation
somehow? If so, how?
 
pg_upgrade + re-indexing is much preferred instead of the 10+ hours the
pg_dump/restore would take (SSD-disks).
 
Thanks.
 
-- Andreas Joseph Krogh
CTO / Partner - Visena AS
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