better way to look at the more recent revision from `alembic history` output

[ChannyClaus]

Describe the use case

alembic history currently prints out the history of revisions to STDOUT in reverse-chronological order. personally as a user, i am a lot more interested in the recent revisions than the initial one and it can be not particularly ergonomic to have to scroll up to look at the recent commits.

Databases / Backends / Drivers targeted
all of them?

Example Use

included in the use case.

Additional context

i think there can be two different ways to go about implementing this:

• we could add a flag --reverse to reverse the output, although this might be of relatively small value since tail -r on macos or tac on linux would achieve exactly the same via piping (unless alembic history output decides to add a header or something)
• the better way, i think, is to make it scrollable via less-like interface like git log does by default. since the output stays exactly the same, this should be backwards-compatible while achieving the goal of allowing the users to look at the most recent revision with no extra effort beyond just typing alembic revision.

Have a nice day!

[CaselIT]

Hi,

I think this could be useful.
The first option seems easier to implement, unless the python stdlib has a way of emulating a less like interface.

Regarding the name of the flag I think something like --chronological would be clearer

[funkindy]

Little bump here. Looks like a good feature for huge migration count.

[vinthara]

Hi !

Could try and work on it (would be my first PR ever). Some guidance would be much appreciated !

I was thinking of (three options) :

--chronological Show the revisions in the choronological order
--head NUM, Print the first NUM lines
--tail NUM, Print the last NUM lines

Something like this :

alembic history --choronological --tail 5

-- EDIT -- :

More like something like this then

--oldestfirst            Show the revisions in the revisions order

Or --baseontop

alembic history --oldestfirst -r-5:heads
# prints last 5 revision 
# (head-4) ...
# (head-3) ...
# (head-2) ...
# (head-1) ...
# (head) ...

[CaselIT]

I'm not sure chronological can be implemented, since alembic migration don't have a date attached to them. Unless you meant something different by it

[vinthara]

Hi,

I think this could be useful. The first option seems easier to implement, unless the python stdlib has a way of emulating a less like interface.

Regarding the name of the flag I think something like --chronological would be clearer

Oh It was simply based on your old post, (the default order of alembic history being reversed, going from (head) ... all the way down to (base))
So I figured using the flag --chronogically would print the revisions from (base)...(heads)

[zzzeek]

migration files do have a "date" inside them so as long as that's present I would think chronological is feasible

[CaselIT]

oh ok, makes sense. maybe it makes sense --oldestfist as flag to indicate the reversed order.

regarding the date, sure it's in the migration by default, but I'm not sure how useful it would be to order them by date

[vinthara]

I gave it a go, would appreciate some feedback (honest and brutal is fine) on my forked repo.
Would also appreciate guidance for writing tests.

https://github.com/vinthara/alembic/tree/feature/history-reversed-order

[CaselIT]

could you open a pr, maybe in draft, to simplify the review?

thanks