I have an existing app which uses SQLAlchemy for DB access. It works well.
Now I want to introduce DB migrations, and I read alembic is the recommended way. Basically I want to start with the "current DB state" (not empty DB!) as revision 0, and then track further revisions going forward.
So I installed alembic (version 1.7.3) and put
from my_project.db_tables import Base
target_metadata = Base.metadata
into my env.py. The Base is just standard SQLAlchemy Base = sqlalchemy.ext.declarative.declarative_base() within my project (again, which works fine).
Then I ran alembic revision --autogenerate -m "revision0", expecting to see an upgrade() method that gets me to the current DB state from an empty DB. Or maybe an empty upgrade(), since it's the first revision, I don't know.
Instead, the upgrade() method is full of op.drop_index and op.drop_table calls, while downgrade() is all op.create_index and op.create_table. Basically the opposite of what I expected.
Any idea what's wrong?
What's the recommended way to "initialize" migrations from an existing DB state?
OK, I figured it out.
The existing production DB has lots of stuff that alembic revision --autogenerate is not picking up on. That's why its generated migration scripts are full of op.drops in upgrade(), and op.creates in downgrade().
So I'll have to manually clean up the generated scripts every time. Or automate this cleanup Python script cleanup somehow programmatically, outside of Alembic.
Related
We are experiencing an issue on v2011, where using the admin aspect with the updatesystem command, does not actaully do an updatesystem. By that i mean, it does not perform any typesystem updates or impex etc. where have also tried the command with passing a config file but still the same result. Also, if the completes it shuts down the container and just starts it back up again.
Tried basing the typeSystem only argument, and also a passing a config json file. Check DB SystemINit table to ensure it was not locked
I have (several) database project in a solution. In one I have a referesnce to a dacpac (this is ACTUALLY a copy of one of the main databases as we take a SQL snapshot at end of day and some code needs to reference this (DBANME_Daily) rather that DBNAME).
now this builds correctly, the code with SELECT * FROM DBNAME_DAILY.schema.table all compiles and builds with no error.
ON deployment however I get the unresolved reference to DBNAME_DAILY.schema.table
You want to add a dacpac for that database as a reference, using variables for the database. Should be different database, different names. You'd then use that variable in your code and you'd pass in the variable name for your build/publish tasks depending on the environment.
This is a little older article, but still pretty accurate:
http://schottsql.com/2012/10/31/ssdt-external-database-references/
You can tweak that a little bit using a variable for the database name. When I wrote this, it was mostly just a different database with the same name across environments. For your case, you'd just use the DB variable. Then replace your "DBName.schema." with "[$DBNameVariable].schema." (or something similar)
Sorted, my mistake was the dacpac reference would only allow the project to BUILD. For deployment the database DBNAME_DAILY MUST EXIST.
Lesson Learnt.
I have an app configured
config :my_app,
ecto_repos: [MyApp.Repo, MyApp.LegacyRepo]
MyApp.Repo's migrations are managed by Ecto.
MyApp.LegacyRepo migrations are handled by Rails and error out on mix ecto.migrate
Is there a way to specify "I have two repos, but please ignore the second for migrations"?
Another option is to change your config.exs. Change it to...
config :my_app, ecto_repos: [MyApp.Repo]
According to the ecto.migrate documentation...
The repositories to migrate are the ones specified under the
:ecto_repos option in the current app configuration. However, if the
-r option is given, it replaces the :ecto_repos config.
Not having a MyApp.LegacyRepo in ecto_repos doesn't prevent reads or writes or anything else you'd expect. It just configures the migration task.
You can pass a repo into mix ecto.migrate like this
mix ecto.migrate -r MyApp.Repo
You can update test/test_helper.ex in a phoenix app to only run one repo migrations like this
Mix.Task.run "ecto.migrate", ["-r", "MyApp.Repo", "--quiet"]
I am going to make some modifications to methods and the biosphere3 database. As I might break things (I have before), I would like to create backups.
Thankfully, there exist backup() methods for just this. For example:
myBiosphere = Database('biosphere3')
myBiosphere.backup()
According to the docs, this "Write[s] a backup version of the data to the backups directory." Doing so indeed creates a backup, and the location of this backup is conveniently returned when calling backup().
What I wish to do is to load this backup and replace the database I have broken, if need be. The docs seem to stay silent on this, though the docs on serialize say "filepath (str, optional): Provide an alternate filepath (e.g. for backup)."
How can one restore a database with a saved version?
As a bonus question: how is increment_version(database, number=None) called, and how can one use it to help with database management?
The code to backup is quite simple:
def backup(self):
"""Save a backup to ``backups`` folder.
Returns:
File path of backup.
"""
from bw2io import BW2Package
return BW2Package.export_obj(self)
So you would restore the same as with any BW2Package:
from brightway2 import *
BW2Package.import_file(filepath)
However, if would recommend using backup_project_directory(project) and restore_project_directory(filepath) instead, as they don't go through an (older) intermediate format.
increment_version is only for the single file database backend, and is invoked automatically every time the database is saved. You could add versioning to the sqlite database backend, but this is non-trivial.
I got XHProf working with XHgui. I like to clear or restart fresh profiling for certain site or globally. How do i clear/reset XHprof? I assume i have to delete logs in Mongo DB but I am not familiar with Mongo and I don't know the tables it stores info.
To clear XHProf with XHGui, log into mongo db and clear the collection - results as following:
mongo
db.results.drop()
The first line log into mongo db console. The last command, drops collection results that is is going to be recreated by the XHGui on the next request that is profiled
Some other useful commands:
show collections //shows all collection
use results //the same meaning as mysql i believe
db.results.help() //to find out all commands available for collection results
I hope it helps
I have similar issue in my Drupal setup, using Devel module in Drupal.
After a few check & reading on how xhprof library save the data, i'm able to figure out where the data is being saved.
The library will check is there any defined path in php.ini
xhprof.output_dir
if there's nothing defined in your php.ini, it will get the system temp dir.
sys_get_temp_dir()
In short, print out these value to find the xhprof data:
$xhprof_dir = ini_get("xhprof.output_dir");
$systemp_dir = sys_get_temp_dir();
if $xhprof_dir doesn't return any value, check the $systemp_dir, xhprof data should be there with .xhprof extension.