* migratex api uses tx now instead of db
we want to be able to do external queries outside of the migration itself
inside of the same transaction for version checking. if we don't do this, we
risk the case where we set the version to the latest but we don't run the
table creates at all, so we have a db that thinks it's up to date but doesn't
even have any tables, and on subsequent boots if a migration slides in then
the migrations will run when there are no tables. it was unlikely, but now
it's dead.
* tx friendly table exists check
the previous existence checker for dbs was relying on getting back errors
about the db not existing. if we use this in a tx, it makes the whole tx
invalid for postgres. so, now we have count the table queries which return a 1
or a 0 instead of a 1 or an error so that we can check existence inside of a
transaction. voila.
* move mattes migrations to migratex
* changes format of migrations to migratex format
* updates test runner to use new interface (double checked this with printlns,
the tests go fully down and then up, and work on pg/mysql)
* remove mattes/migrate
* update tests from deps
* update readme
* fix other file extensions
code is feature complete in the general sense, with minor TODO left.
this is just a patch with 'migratex' and does not use it for fn's migrations
yet, would like to get feedback prior to doing that.
presenting:
A migration library loosely based on pressly/goose and mattes/migrate design,
that does migrations across a smattering of sql databases by only accepting a
`*sqlx.DB`.
why?
* goose didn't support kindly allowing us to rebind transactions based on a
given db to various dialects or offer oracle support
* goose didn't support locking the db (maybe not needed with tx? it's late..
we may want to lock the whole db eventually?)
* goose requires us to do semi-complex migration to it from mattes/migrate
* mattes has stepped down as migrate maintainer and the project is in flux
* mattes/migrate did not allow us to define migrations in go and rebind to
different dialects, an issue since we need to insert ids in our own format and
can't define this in sql
* neither handled context plumbing and risked issues there for various
reasons (deadlock, etc).
* I think I'm forgetting 1 or 2
in the style of goose, this lets us define `*sqlx.Tx` up and down funcs in go
code, but uses mattes' migration table so we don't need to migrate that and
retains its lock behavior with added tx sugar and less errors. most
importantly, this code is terse, leveraging sqlx to support a lot of sql dbs
(unlike mattes) and we control this. there is one useful TODO to handle
migrations failing at startup more gracefully, in prod stuff like that will be
nice to have. open to discussion of putting in a separate library, the
landscape of go sql migrators is... really something.
TODO make test suite and test against sqlite3, pg, mysql [, oracledb] like we
have for our own unit tests. I'm thinking it's faster to wire up through
there and use our bevy of migrations?
