Issue
sql_error_code = 00000 LOG: checkpoint starting: time, and similar log lines are appearing in the logs for professional-tier Heroku Postgres databases.
[121-1] sql_error_code = 00000 LOG: checkpoint starting: time
[122-1] sql_error_code = 00000 LOG: checkpoint complete: wrote 0 buffers (0.0%); 0 WAL file(s) added, 0 removed, 1 recycled; write=0.001 s, sync=0.000 s, total=0.006 s; sync files=0, longest=0.000 s, average=0.000 s; distance=16384 kB, estimate=31129 kB
[299-1] sql_error_code = 00000 LOG: checkpoint starting: force wait
...
[300-1] sql_error_code = 00000 LOG: checkpoint complete: wrote 0 buffers (0.0%); 0 WAL file(s) added, 0 removed, 1 recycled; write=0.001 s, sync=0.000 s, total=0.007 s; sync files=0, longest=0.000 s, average=0.000 s; distance=16383 kB, estimate=31129 kB
Resolution
These log lines don't indicate any errors as sql_error_code = 00000 LOG translates to "successful completion". See: Why am I getting "sql_error_code = 00000" in my PostgreSQL logs? Is this an error from my queries?.
The checkpoint logs are part of the automatic WAL (Write-Ahead Logging) archiving activity that allows us to protect your database from catastrophic failures and is used in continuous protection and other Heroku Postgres features like database forks and followers.