R – How to get the database under version control with Perl

databasemigrationperlversion control

I've been looking at the options for getting our database schemas under version control. It seems that Ruby folks have got Rails Migrations, and .NET folks have got a few options (for instance this, this, and this). What about Perl?

I've seen this thread on PerlMonks which doesn't have much, although it mentions DBIX::Migration::Directories. Is anyone actually using this module, or some other module? Or do you roll your own DB migration solutions?

Gratuitous details:

We don't use DBIx::Class for the most part
We use MySQL
We use SVN

Best Answer

In POPFile we use our own solution. We store a schema version number in the db and if the program detects that there is a newer schema, it will update the db accordingly. This is not exactly the best and most fun part of our code.

To be honest, I fail to see the advantage of using DBIx::Migration::Directories if you aren't already using DBIx::Class. You have to provide the SQL and the version numbers and the database handle. You might as well provide a little more code to find the sql file and and feed it to the database.

Of course, having the schema in version control is a great bonus.

Related Solutions

Git – How to undo git reset –hard HEAD~1

Pat Notz is correct. You can get the commit back so long as it's been within a few days. git only garbage collects after about a month or so unless you explicitly tell it to remove newer blobs.

$ git init
Initialized empty Git repository in .git/

$ echo "testing reset" > file1
$ git add file1
$ git commit -m 'added file1'
Created initial commit 1a75c1d: added file1
 1 files changed, 1 insertions(+), 0 deletions(-)
 create mode 100644 file1

$ echo "added new file" > file2
$ git add file2
$ git commit -m 'added file2'
Created commit f6e5064: added file2
 1 files changed, 1 insertions(+), 0 deletions(-)
 create mode 100644 file2

$ git reset --hard HEAD^
HEAD is now at 1a75c1d... added file1

$ cat file2
cat: file2: No such file or directory

$ git reflog
1a75c1d... HEAD@{0}: reset --hard HEAD^: updating HEAD
f6e5064... HEAD@{1}: commit: added file2

$ git reset --hard f6e5064
HEAD is now at f6e5064... added file2

$ cat file2
added new file

You can see in the example that the file2 was removed as a result of the hard reset, but was put back in place when I reset via the reflog.

Git – I ran into a merge conflict. How to abort the merge

Since your pull was unsuccessful then HEAD (not HEAD^) is the last "valid" commit on your branch:

git reset --hard HEAD

The other piece you want is to let their changes over-ride your changes.

Older versions of git allowed you to use the "theirs" merge strategy:

git pull --strategy=theirs remote_branch

But this has since been removed, as explained in this message by Junio Hamano (the Git maintainer). As noted in the link, instead you would do this:

git fetch origin
git reset --hard origin

Best Answer

Related Solutions

Git – How to undo git reset –hard HEAD~1

Git – I ran into a merge conflict. How to abort the merge

Related Topic