Re: Seeking Suggestions for Best Practices: Archiving and Migrating Historical Data in PostgreSQL

What would you use for backup if PG hosted on Windows

On Fri, May 30, 2025 at 2:10 PM Ron Johnson <ronljohnsonjr(at)gmail(dot)com> wrote:

> Hmm... that was a few years ago, back when v12 was new. It took about a
> month (mainly because they didn't want me running exports during "office
> hours").
>
> There were 120 INSERT & SELECT (no UPDATE or DELETE) tables, so I was able
> to add indices on date columns, create by-month views. (We migrated the
> dozen or so *relatively* small UPDATE tables on cut-over day. On that
> same day, I migrated the current month and the previous month's data in
> those 120 tables.
>
> I made separate cron jobs to:
> - export views from Oracle into COPY-style tab-separated flat files,
> - lz4-compress views that had finished exporting, and
> - scp files that were finished compressing, to an AWS EC2 VM.
>
> These jobs pipelined, so there was always a job exporting, always a job
> ready to compress tsv files, and another job ready to scp the lz4 files.
> When there was nothing for a step to do, the job would sleep for a couple
> of minutes, then check if there was more work to do.
>
> On the AWS EC2 VM, a different cron job waited for files to finish
> transferring, then loaded them into the correct table. Just like with the
> source host jobs, the "load" job would sleep a bit and then check for more
> work. I manually applied Indices.
>
> The AWS RDS PG12 database was about 4TB. Snapshots were handled by AWS.
> If this had been one of my on-prem systems, I'd have used pgbackrest.
> (pgbackrest is impressively fast: takes good advantage of PG's 1GB file
> max, and globs "small" files into one big file.)
>
> On Fri, May 30, 2025 at 12:15 PM Andy Hartman <hartman60home(at)gmail(dot)com>
> wrote:
>
>> what was the duration start to finish of the migration of the 6tb of
>> data. then what do you use for a quick backup after archived PG data
>>
>> Thanks.
>>
>> On Fri, May 30, 2025 at 11:29 AM Ron Johnson <ronljohnsonjr(at)gmail(dot)com>
>> wrote:
>>
>>> On Fri, May 30, 2025 at 3:51 AM Motog Plus <mplus7535(at)gmail(dot)com> wrote:
>>>
>>>> Hi Team,
>>>>
>>>> We are currently planning a data archival initiative for our production
>>>> PostgreSQL databases and would appreciate suggestions or insights from the
>>>> community regarding best practices and proven approaches.
>>>>
>>>> **Scenario:**
>>>> - We have a few large tables (several hundred million rows) where we
>>>> want to archive historical data (e.g., older than 1 year).
>>>> - The archived data should be moved to a separate PostgreSQL database
>>>> (on a same or different server).
>>>> - Our goals are: efficient data movement, minimal downtime, and safe
>>>> deletion from the source after successful archival.
>>>>
>>>> - PostgreSQL version: 15.12
>>>> - Both source and target databases are PostgreSQL.
>>>>
>>>> We explored using `COPY TO` and `COPY FROM` with CSV files, uploaded to
>>>> a SharePoint or similar storage system. However, our infrastructure team
>>>> raised concerns around the computational load of large CSV processing and
>>>> potential security implications with file transfers.
>>>>
>>>> We’d like to understand:
>>>> - What approaches have worked well for you in practice?
>>>>
>>>
>>> This is how I migrated 6TB of data from an Oracle database to
>>> Postgresql, and then implemented quarterly archiving of the PG database:
>>> - COPY FROM (SELECT * FROM live_table WHERE date_fld in
>>> some_manageable_date_range) TO STDOUT.
>>> - Compress
>>> - scp
>>> - COPY TO archive_table.
>>> - Index
>>> - DELETE FROM live_table WHERE date_fld in some_manageable_date_range
>>> (This I only did in the PG archive process
>>>
>>> (Naturally, the Oracle migration used Oracle-specific commands.)
>>>
>>> - Are there specific tools or strategies you’d recommend for ongoing
>>>> archival?
>>>>
>>>
>>> I write generic bash loops to which you pass an array that contains the
>>> table name, PK, date column and date range.
>>>
>>> Given a list of tables, it did the COPY FROM, lz4 and scp. Once that
>>> finished successfully, another script dropped archive indices on the
>>> current table, COPY TO and CREATE INDEX statements. A third script did the
>>> deletes.
>>>
>>> This works even when the live database tables are all connected via FK.
>>> You just need to carefully order the tables in your script.
>>>
>>>
>>>> - Any performance or consistency issues we should watch out for?
>>>>
>>>
>>> My rules for scripting are "bite-sized pieces" and "check those return
>>> codes!".
>>>
>>>
>>>> Your insights or any relevant documentation/pointers would be immensely
>>>> helpful.
>>>>
>>>
>>> Index support uber alles. When deleting from a table which relies on a
>>> foreign key link to a table which _does_ have a date field, don't hesitate
>>> to join on that table.
>>>
>>> And DELETE of bite-sized chunks is faster than people give it credit for.
>>>
>>> --
>>> Death to <Redacted>, and butter sauce.
>>> Don't boil me, I'm still alive.
>>> <Redacted> lobster!
>>>
>>
>
> --
> Death to <Redacted>, and butter sauce.
> Don't boil me, I'm still alive.
> <Redacted> lobster!
>