This is an original planning guide. It is not a vendor manual, an official standard, or legal advice. Example addresses use documentation ranges. Review every command before you paste it.
What this hour is for
The calculator and the decoder turn an LSN you type into a file name. They do not connect. A timeline is a label for a history you already have, not a rewind you start.
Do not delete WAL during the reading. Do not promote a standby. Do not remove a timeline to make a name look tidy.
192.0.2.10, 198.51.100.0/24, 203.0.113.0/24, and 2001:db8::/32 are documentation. example.com is a documentation name. A sample password is replaced. It is not a password you keep.
The change you can finish
Apply nothing while you are writing the note. When the lab window opens, it is one change on the database named in the ticket. Read the draft, then the database, then decide.
Rollback is the backup, the file, or the snapshot you saved first. You do not invent a rollback after the only copy is gone.
- Type one LSN you already have, or say sketch.
- Read the file name.
- Do not delete WAL.
- Do not promote.
- Stop.
Mistakes that outlive the statement
PostgreSQL WAL, LSN and Timelines Explained goes wrong in a small set of ways. The list is here so the ticket can forbid them before the window.
- WAL deleted during the reading.
- A standby promoted.
- A timeline removed.
- An LSN from a cluster you do not administer.
Decisions to write down
One decision for PostgreSQL WAL, LSN and Timelines Explained: The LSN is written or it is a sketch. The file name was read. Nothing was deleted. And nothing was promoted.
Checks before you call it done
Confirm this before you call the change done: The cluster is written or it is a sketch. The file name was read. Nothing was deleted. Nothing was promoted. And the database is yours. If one of those fails, stop.
Before you leave the database
PostgreSQL WAL, LSN and Timelines Explained ends when the database in the prompt is the database in the ticket. If it is not, you are on the wrong database. Stop.
The draft stays a draft until a person has read the names in it. A generator does not log into the database. You delete a line that names a host, a database, or an account you did not write down.
192.0.2.10, 198.51.100.0/24, 203.0.113.0/24, and 2001:db8::/32 are documentation. example.com is a documentation name. They belong in the note. They are not values you leave on a database because a draft included them.
prompt-for-this is a reminder that a secret is missing. It is not a password, a key, or a token you save in the ticket or in git. A sample password in a draft is replaced. It is not a password you keep.
One change is the window. If two things move and the result is wrong, you will not know which one did it.
If the same step fails twice, stop for the day. Restore the copy you took first.
A second person reads the database name and the change aloud. If they cannot find them in the ticket, the note is not done.
This page is a planning guide. It is not a vendor manual, not an official standard, and not permission to touch a database you do not administer. You do not disable authentication, a firewall, or TLS to make a check pass.
Tools for this guide
These tools run in the browser on this site. They do not log into your machines.
Related pillar guides
More in this cluster
The pillar for this page, and the next published pages filed with it.