Re: pg_upgrade and schema complexity...

On 6/2/23 18:06, Ron wrote:
> On 6/2/23 19:58, Adrian Klaver wrote:
>> On 6/2/23 17:44, Ron wrote:
>>> Ran into this when upgrading from 13.11 to 15.3...
>>>
>>> The pg_restore phase failed with "ERROR: out of shared memory", and 
>>> recommended that I increase max_locks_per_transaction. Doing so let 
>>> the process run to completion.
>>>
>>> It took 12.5 minutes to upgrade a 13GB instance.  Soon after, I 
>>> upgraded a 78GB cluster, and it only took 3.1 minutes.
>>
>> Where/how did you measure  those sizes?
> 
> Does it really matter?
> 
> START_SECS=$(date +"%s")
> pg_upgrade ...
> FINISH_SECS=$(date +"%s")
> ET=`echo "scale=2;(${FINISH_SECS} - ${START_SECS})/60" | bc`
> date +"%F %T pg_upgrade finished.  Elapsed time: ${ET} minutes."

Unless I'm not mistaken the above is how the elapsed time was measured. 
I was looking for the procedure for determining the size.

> 
> (Text copied between air-gapped computers, so there might be errors.)
> 
>>>
>>> (Both are VMs (same number of CPUs and RAM) connected to the same SAN.)
>>>
>>> A "pg_dump --schema-only" of the two systems shows that the 
>>> small-but-slow schema is 5.9M lines.
>>
>> Anything special you are doing in this cluster to create all those lines?
> 
> I do nothing; the schema is provided by the vendor.

Alright so it is not your design, but you do have an idea of what is in 
the database correct?


> 
>>
>> What is the line count for the other instance?
> 
> 227K rows.
> 
>>>
>>> Is this to be expected of such a huge schema?
>>>
> 

-- 
Adrian Klaver
adrian.klaver@aklaver.com