[documentation] List pending Postgres patches

[aarne]

Currently the project relies on patching Postgres source.

It would be nice to list the pending patches with current status to give people the understanding how far we are from getting to a state where one would be able to use official Postgres images without modifications.

Also it would be nice to just in case restate the goal of running as an extension of top of standard Postgres instead of maintaining a set of custom patches ... this seems obvious but might not be the case :)

[zaneduffield]

I would appreciate this documentation as well. I just went looking over the Postgres mailing lists and commitfest site to try and find the status of these patches, but I couldn't find anything.

[mason-sharp]

There is a PR open right now that eliminates the need for one of the patch files.

We want to work towards reducing what is patched. Fully eliminating them will likely take closer cooperation with the Postgres community.

It may also be possible to also eliminate them if the user does not need certain features, like delta apply columns, and they have a willingness to tolerate the possibility of inconsistent data when there are concurrent updates across nodes (if could be unlikely if, for example, easily identifiable subsets of data tends to flow in one direction like region = 'EU'), we could try to detect if patches are not applied and not use patch-dependent features.

[zaneduffield]

We want to work towards reducing what is patched. Fully eliminating them will likely take closer cooperation with the Postgres community.

That was my assumption, but it's good to hear.

It may also be possible to also eliminate them if the user does not need certain features

In the meantime this could be a good QoL improvement. Runtime detection would be ideal, but it would also be an improvement if there were simply some compiler defines that controlled the compatibility with standard Postgres.

[aarne]

I think for adoption it would be very beneficial to separate feature that require patching from the ones that can run as plain plugin. Delta apply columns are super nice, but there is a big subset of use-cases that work with just the normal conflict resolution.

considering the state of pglogical it would be an big step forward for postgres active-active community effort