Simple database patching strategy _ lornajane

One problem that seems to need solving too often is how to keep databases in sync across different platforms, different developers working on a project, and deploying database changes along with code changes. Hollywood u database There are lots of ways of approaching this, none of them are really excellent however and personally I tend to err on the side of simple being better. Data recovery ipad Fewer dependencies means a solution more likely to work on every platform (and no additional complications for the live platform). Database vs server Usually this means patch files of some kind – here’s an outline of my usual approach.


Database is in transition For the impatient:

• for any changes, create a numbered patch file e.g. Data recovery ios patch-1.sql, including the change and an update statement to bring the version meta data to match the patch file

This new row will hold information about what patch version the database is up to. Database data types Every patch that is created will update this number so that it is possible to tell which patches have and have not been applied. Data recovery johannesburg Create an Initial Data Structure

Firstly create a database directory for all these files to live in. Iphone 5 data recovery software This should be outside your web root but inside your source control project.

You will also want to populate tables which hold things like lookup values, country lists, that sort of thing, so that these are set up. Database operations People starting to develop with this project, or if the application needs to be deployed to somewhere new, can use this file as a starting point. Database index Create Patches for Changes

This is where the discipline element comes in – no direct edits on the database are allowed! Instead, write the SQL for your change and place it in the patch file, then run it against the database. Database crud If that sounds too much like hard work then copy/paste the SQL you use to make changes, or the SQL generated by whatever SQL tool you use, and place it in the file.

Every file must have its own incrementing version number in its file name, e.g. Drupal 8 database patch-1.sql, patch-2.sql etc. Data recovery disk Within the file the version must also be updated to match, with a statement like:

• Under no circumstances is it acceptable to edit a patch file that has been committed to source control. Database 3 tier architecture Someone might have run it already and you’ll confuse everyone completely.

• Make a script to look up the database settings in the config file of your application, query the database for what version it is at, and run any outstanding scripts. Data recovery orlando This makes life much easier especially if you have large numbers of scripts (I’ve seen the patch numbers hit the hundreds)

• A possible adaptation of this approach is to create patch files for use for updating a database, but to also update the install.sql file to make it correct at any point in time, this means a much shorter and easier setup time for new deployements/developers. Database cardinality The version awareness works in the same way regardless

• Creating a sample database which creates a few records in each table can really help for development purposes – its quicker for people to get set up and attain a working system that they can make progress with.

I’m sure there are many improvements and variations on this theme of simple database patching, leave a comment and let me know what works for you and why!

In my day job, we use a particular ORM a lot, which does the same kind of thing wrapped in a little DSL – and from it, I’d suggest the following:

First, especially for /big/ projects in a distributed VCS, use timestamps instead of sequential numbers. Database unit testing It really reduces the potential pain at the cost of looking slightly uglier.

Second, if you want to get a bit fancy, have a ‘schema_versions’ (or similarly named) table with a ‘version’ column. I data recovery software free download Every time you apply a patch, insert a new row into that table with the version ID/timestamp. O review database This lets you have a stable deployment with migrations 1,2,3 and a staging one with 1,2,3,4,5,then backport a bugfix that relies on migration 5 but not 4 all by itself, then do a migration with 4,6,7,… Database in recovery when the time comes to upgrade stable by a major version.

It also lets you have ‘up’ and ‘down’ migrations – so you can apply and unapply each one individually if you want to – but I’ve never found that to be particularly useful. Data recovery wizard professional But then, I have a bad habit of doing data migrations at the same time as the schema migrations… Data recovery open source 😉

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