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Dbmover plugin to hoist conditional statements
SQL extension plugin to support conditionals in your schema., (*1)
Normally when loading a full schema (e.g. psql -u user -p database <
my-schema.sql) you are not allowed to use IF/ELSE statements - these can
only appear inside of procedures. It goes without saying however that for more
complex migrations, sometimes you're going to want them., (*2)
$ composer require dbmover/conditionals
For general DbMover usage, see dbmover/core., (*3)
By itself this package doesn't do much; you'll usually want the vendor-specific
plugins (currently dbmover/pgsql-conditionals or dbmover/mysql-conditionals
instead. These plugins implement the wrapping logic so your IF statements are
valid inside the schema (essentially, they create a throwaway "lambda" function
with your IF, run it and discard it afterwards)., (*4)
The IFs are run both on __invoke as well as on __destruct. It's up to you
to make sure they will never throw an error (e.g. check information_schema for
stuff first)., (*5)
Say you want to rename table foo to bar. In your schema you can change the
table name, but that would cause DbMover to simply drop foo and create bar,
losing all data in foo. Generally not what you want. A workaround would be to
copy the definition for bar to foo, run DbMover, copy the data, remote the
definition for bar and run DbMover again - but this is the sort of manual work
DbMover aims to avoid..., (*6)
A better strategy is to query information_schema.tables to see if the new
table exists yet, and if not perform the rename there:, (*7)
IF NOT FOUND (SELECT * FROM information_schema.tables
WHERE table_catalog = DBMOVER_DATABASE AND table_schema = 'public')
THEN
ALTER TABLE foo RENAME TO bar;
END IF;
Note that the lambda has access to the text variable DBMOVER_DATABASE
automatically. It contains the name of the database DbMover is currently
operationg on. This is handy for when you have multiple databases sharing a
single schema file (e.g. related projects with just a few overrides)., (*8)
See dbmover/core., (*9)
Dbmover plugin to hoist conditional statements
MIT
Dbmover plugin to hoist conditional statements
MIT
Dbmover plugin to hoist conditional statements
MIT