Re: Upgrade from PG12 to PG

running /usr/lib/postgresql15/bin/pg_upgrade -v -p 5431 -P 5432 -k

gives you in the output :

...
"/usr/lib/postgresql15/bin/pg_dump" --host /pg/PG15 --port 5431 
--username postgres --schema-only --quote-all-identifiers 
--binary-upgrade --format=custom --verbose 
--file="/pg/PG15/system/pg_upgrade_output.d/20230720T184333.610/dump/pg_upgrade_dump_16385.custom" 
'dbname=dbname' >> 
"/pg/PG15/system/pg_upgrade_output.d/20230720T184333.610/log/pg_upgrade_dump_16385.log" 
2>&1
...


so, yes pg_ugrade start a pg_dump session,


even a pg_restore at the end, runs about 7 hours

"/usr/lib/postgresql15/bin/pg_restore" --host /pg/PG15 --port 5432 
--username postgres --create --exit-on-error --verbose --dbname 
template1 
"/pg/PG15/system/pg_upgrade_output.d/20230720T184333.610/dump/pg_upgrade_dump_16385.custom" 
 >> 
"/pg/PG15/system/pg_upgrade_output.d/20230720T184333.610/log/pg_upgrade_dump_16385.log" 
2>&1

with a lot of lines in the logfiles  like:  pg_restore: executing BLOB 
11108809


Server is a VM server, my VM has 64GB SuseSLES  attached to a SAN with 
SSD disk (Hp3Par)

2)vacuumlo

lovacum -n =>  I have vacuumlo, running this:

vacuumlo  dbname  -v

postgres@dbfluxd02:/pg/data> vacuumlo  dflux -v
Connected to database "dflux"
Checking message_oid in fluxnaf.flux_message_content
Checking payload_oid in fluxnaf.bridge_payload_content
Successfully removed 0 large objects from database "dflux".

and again same issues



On 20/07/2023 16:51, Scott Ribe wrote:
>> On Jul 20, 2023, at 7:46 AM, Jef Mortelle <jefmortelle@gmail.com> wrote:
>>
>> So: not possible to have very little downtime if you have a database with al lot rows containing text  as datatype,
aspg_upgrade needs 12hr for 24 milj rows in pg_largeobject.
 
> We need to get terminology straight, as at the moment your posts are very confusing. In PostgreSQL large objects and
textare not the same. Text is basically varchar without a specified length limit. Large object is a blob (but not what
SQLcalls a BLOB)--it is kind of like a file stored outside the normal table mechanism, and provides facilities for
partialreads, etc: https://www.postgresql.org/docs/15/largeobjects.html. There are a number of ways to wind up with
referencesto large objects all deleted, but the orphaned large objects still in the database.
 
>
> First thing you should do: run lovacuum -n to find out if you have orphaned large objects. If so, start cleaning
thoseup, then see how long pg_upgrade takes.
 
>
> Second, what's your hardware? I really don't see dump & restore of a 1TB database taking 6 hours.
>
>> Alsready tried to use --link and --jobs, but you cannot ommit the "select  lo_unlink ...."   for every rows
containingdatatype text in your database that the pg_* program creates in the export/dump file.
 
> Terminology again, or are you conflating two different issues? pg_upgrade --link does not create a dump file.