Re: Online enabling of checksums

Hello, Magnus, Peter!

I'm excited that this feature emerged, thanks for the patch. Hope it will help to fix some mistakes made during initdb long time ago...

> 22 февр. 2018 г., в 18:22, Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com> написал(а):
>
> On 2/21/18 15:53, Magnus Hagander wrote:
>> *Two new functions are added, pg_enable_data_checksums() and
>> pg_disable_data_checksums(). The disable one is easy -- it just changes
>> to disable. The enable one will change the state to inprogress, and then
>> start a background worker (the “checksumhelper launcher”). This worker
>> in turn will start one sub-worker (“checksumhelper worker”) in each
>> database (currently all done sequentially).*
>
> This is at least the fourth version of the pattern launcher plus worker
> background workers. I wonder whether we can do something to make this
> easier and less repetitive. Not in this patch, of course.

Peter, can I ask for some pointers in searching for previous versions?
I want to review patch this patch and some code comparision could be handy....

So far I've found only this [0,1] (without code) and threads mentioned by Magnus [2,3]

Or do you mean extracting "worker+lancher" for reuse for other purposes?

Best regards, Andrey Borodin.

[0] https://www.postgresql.org/message-id/flat/E2B195BF-7AA1-47AF-85BE-0E936D157902%40endpoint(dot)com#E2B195BF-7AA1-47AF-85BE-0E936D157902(at)endpoint(dot)com <https://www.postgresql.org/message-id/flat/E2B195BF-7AA1-47AF-85BE-0E936D157902(at)endpoint(dot)com#E2B195BF-7AA1-47AF-85BE-0E936D157902@endpoint.com>
[1] https://www.postgresql.org/message-id/flat/7A00D9D1-535A-4C37-94C7-02296AAF063F%40endpoint(dot)com#7A00D9D1-535A-4C37-94C7-02296AAF063F(at)endpoint(dot)com <https://www.postgresql.org/message-id/flat/7A00D9D1-535A-4C37-94C7-02296AAF063F(at)endpoint(dot)com#7A00D9D1-535A-4C37-94C7-02296AAF063F@endpoint.com>
[2] https://www.postgresql.org/message-id/flat/CABUevEx8KWhZE_XkZQpzEkZypZmBp3GbM9W90JLp%3D-7OJWBbcg%40mail(dot)gmail(dot)com#CABUevEx8KWhZE_XkZQpzEkZypZmBp3GbM9W90JLp=-7OJWBbcg(at)mail(dot)gmail(dot)com <https://www.postgresql.org/message-id/flat/CABUevEx8KWhZE_XkZQpzEkZypZmBp3GbM9W90JLp=-7OJWBbcg(at)mail(dot)gmail(dot)com#CABUevEx8KWhZE_XkZQpzEkZypZmBp3GbM9W90JLp=-7OJWBbcg@mail.gmail.com>
[3] https://www.postgresql.org/message-id/flat/FF393672-5608-46D6-9224-6620EC532693%40endpoint(dot)com#FF393672-5608-46D6-9224-6620EC532693(at)endpoint(dot)com