Logical Replication

[Zvirovyi]

This is a copy of VM PR.

This is an implementation of the Logical Replication specification (WIP): https://docs.google.com/document/d/1f84Z4cZwUD4q4bJsXTTC_PUaZr7pPB0Q6HnQ9cgCX_o/edit?usp=sharing.

Basic testing

1. deploy postgresql and postgresql2
2. juju integrate postgresql:logical-replication-offer postgresql2:logical-replication
3. create testing table with data in the postgresql: create table asd (message text); insert into asd values ('hello');
4. create the same table on the postgresql2 side
5. juju run postgresql/leader add-publication name=asd database=postgres tables=public.asd
6. juju run postgresql2/leader subscribe name=asd
7. check the table on postgresql2 side: select * from asd;
8. add another data to the testing table and observe it was pushed to the postgresql2 subscriber

Key notes

• K8s version does not need cluster_topology_change observer as primary endpoint is resolved automatically and always points to the right unit.

[codecov]

Codecov Report

Attention: Patch coverage is 17.94872% with 288 lines in your changes missing coverage. Please review.

Project coverage is 70.10%. Comparing base (b5b1494) to head (3f7c03d).
Report is 5 commits behind head on main.

Files with missing lines	Patch %	Lines
src/relations/logical_replication.py	16.76%	272 Missing and 6 partials ⚠️
src/backups.py	28.57%	4 Missing and 1 partial ⚠️
src/patroni.py	16.66%	5 Missing ⚠️

❌ Your patch check has failed because the patch coverage (17.94%) is below the target coverage (33.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #899      +/-   ##
==========================================
- Coverage   75.05%   70.10%   -4.96%     
==========================================
  Files          13       14       +1     
  Lines        3704     4054     +350     
  Branches      548      625      +77     
==========================================
+ Hits         2780     2842      +62     
- Misses        718      999     +281     
- Partials      206      213       +7     

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[marceloneppel]

The code looks great! I'll only do some more testing tomorrow.

[marceloneppel]

LGTM!