I'm going to build a new version of my website. The old one is written in Cakephp and for the new one I'm going to use Laravel for that I need to split some large tables into smaller ones.
An example is given above.
But till the development of the new project complete, I need to sync data between these tables.
I cant use Cron or Replication in this situation. Coz Cron job will take time, I cant update the Old code coz it will also take time.
So how do I do this?
I currently have the following setup:
*.mysite.com --> /home/public_html/app/index.php
I want to write some code in index.php that changes the whole document root to /home/public_html/app_prev/index.php based on a condition. The reason for this is that I am doing a migration and if they haven't been migrated yet, I want to serve the old version of the code; once they are migrated. Each user has their own database and I will migrate 1 by 1. Normally it would take seconds to migrate all of them, but this release will take awhile to do.
Is this possible?
Is this recommend when making large database schema changes? Will it cause performance problems/errors?
You could just use a PHP redirect based on the condition that you're looking for. It's no different then serving a different page based on what's coming in.
It's a reasonable implementation if you have many large databases and you're worried about performance. I'd test it by
Keep the old code path and old database.
Migrate a test database over to the new codebase. I don't know how you're doing your logic, but you could have a single column, one entry table in each database that describes whether it's on the old or new code base.
Test that the new codebase works.
Start migrating your databases over, changing that single entry in each database (or however your logic is determined).
I have built a web app using MySQL and php and I'm at the moment trying to figure out the best approach to make a script to automatically update the customers based on the new changes on my development environment without affect the customer data.
So far my first attempt was to check the app version if there is a new one, download the zip with the new and changed files, then I do a mysqldump skipping triggers, etc. of the customers, drop all tables on the customers database, load the scheme and reload the dumped file.
The problem I am facing is that this work if the change in the scheme is a minor one, if I decide to add a couple of columns with new values, or remove unused tables, or to remove unused rows the upload fails.
So my question is whats the best approach to safely update different databases, based on the my development database changes?
I guess the best way is to include queries upgraded script with all the needed queries on it?
But is this the right way?
There is some automatic way to handle this to avoid to manually have to write each change and avoid as well to miss some changes on the script and screw it all?
I really appreciate your opinions as looking around, I didn't find any clear approach of this procedure.
The server is a shared Windows hosting server with Hostgator. We are allowed "unlimited" MS SQL databases and each is allowed "unlimited" space. I'm writing the website in PHP. The data (not the DB schema, but the data) needs to be versioned such that (ideally) my client can select the DB version he wants from a select box when he logs in to the website, and then (roughly once a month) tag the current data, also through a simple form on the website. I've thought of several theoretical ways to do this and I'm not excited about any of them.
1) Put a VersionNumber column on every table; have a master Version table that lists all versions for the select box at login. When tagged, every row without a version number in every table in the db would be duplicated, and the original would be given a version number.
This seems like the easiest idea for both me and my client, but I'm concerned the db would be awfully slow in just a few months, since every table will grow by (at least) its original size every month. There's not a whole lot of data, and there probably never will be, in any one version. But multiplying versions in the same table just scares me.
2) Duplicate the DB every time we tag.
It looks like this would have to be done manually by my client since the server is shared, so I already dislike the idea. But in addition, the old DBs would have to be able to work with the current website code, and as changes are made to the DB structure over time (which is inevitable) the old DBs will no longer work with the new website code.
3) Create duplicate tables (with the version in their name) inside the same database every time we tag. Like [v27_Employee].
The benefit here over idea (1) would be that no table would get humongous in size, allowing the queries to keep up their speed, and over idea (2) it could theoretically be done easily through the simple website tag form rather than manually by my client. The problems are that the queries in my PHP code are going to get all discombobulated as I try to explain which Employee table is joining with which Address table depending upon which version is selected, since they all have the same name, but different; and also that as the code changes, the old DB tables no longer match, same problem as (2).
So, finally, does anyone have any good recommendations? Best practices? Things they did that worked in the past?
Thanks guys.
Option 1 is the most obvious solution because it has the lowest maintenance overhead and it's the easiest to work with: you can view any version at any time simply by adding #VersionNumber to your queries. If you want or need to, this means you could also implement option 3 at the same time by creating views for each version number instead of real tables. If your application only queries one version at a time, consider making the VersionNumber the first column of a clustered primary key, so that all the data for one version is physically stored together.
And it isn't clear how much data you have anyway. You say it's "not a whole lot", but that means nothing. If you really have a lot of data (say, into hundreds of millions of rows) and if you have Enterprise Edition (you didn't say what edition you're using), you can use table partitioning to 'split' very large tables for better performance.
My conclusion would be to do the simplest, easiest thing to maintain right now. If it works fine then you're done. If it doesn't, you will at least be able to rework your design from a simple, stable starting point. If you do something more complicated now, you will have much more work to do if you ever need to redesign it.
You could copy your versionable tables into a new database every month. If you need to do a join between a versionable table and a non-versionable table, you'd need to do a cross-schema join - which is supported in SQL Server. This approach is a bit cleaner than duplicating tables in a single schema, since your database explorer will start getting unwieldy with all the old tables.
What I finally wound up doing was creating a new schema for each version and duplicating the tables and triggers and keys each time the DB is versioned. So, for example, I had this table:
[dbo].[TableWithData]
And I duplicated it into this table in the same DB:
[v1].[TableWithData]
Then, when the user wants to view old tables, they select which version and my code automatically changes every instance of [dbo] in every query to [v1]. It's conceptually fairly simple and the user doesn't have to do anything complicated to version -- just type in "v1" to a form and hit a submit button. My PHP and SQL does the rest.
I did find that some tables had to remain separate -- I made a different schema called [ctrl] into which I put tables that will not be versioned, like the username / password table for example. That way I just duplicate the [dbo] tables.
Its been operational for a year or so and seems to work well at the moment. They've only versioned maybe 4 times so far. The only problem I seem to have consistently that I can't figure out is that triggers seem to get lost somehow. That's probably a problem with my very complex PHP rather than the DB versioning concept itself though.
I've arrived at the point where I realise that I must start versioning my database schemata and changes. I consequently read the existing posts on SO about that topic but I'm not sure how to proceed.
I'm basically a one man company and not long ago I didn't even use version control for my code. I'm on a windows environment, using Aptana (IDE) and SVN (with Tortoise). I work on PHP/mysql projects.
What's a efficient and sufficient (no overkill) way to version my database schemata?
I do have a freelancer or two in some projects but I don't expect a lot of branching and merging going on. So basically I would like to keep track of concurrent schemata to my code revisions.
[edit] Momentary solution: for the moment I decided I will just make a schema dump plus one with the necessary initial data whenever I'm going to commit a tag (stable version). That seems to be just enough for me at the current stage.[/edit]
[edit2]plus I'm now also using a third file called increments.sql where I put all the changes with dates, etc. to make it easy to trace the change history in one file. from time to time I integrate the changes into the two other files and empty the increments.sql[/edit]
Simple way for a small company: dump your database to SQL and add it to your repository. Then every time you change something, add the changes in the dump file.
You can then use diff to see changes between versions, not to mention have comments explaining your changes. This will also make you virtually immune to MySQL upgrades.
The one downside I've seen to this is that you have to remember to manually add the SQL to your dumpfile. You can train yourself to always remember, but be careful if you work with others. Missing an update could be a pain later on.
This could be mitigated by creating some elaborate script to do it for you when submitting to subversion but it's a bit much for a one man show.
Edit: In the year that's gone by since this answer, I've had to implement a versioning scheme for MySQL for a small team. Manually adding each change was seen as a cumbersome solution, much like it was mentioned in the comments, so we went with dumping the database and adding that file to version control.
What we found was that test data was ending up in the dump and was making it quite difficult to figure out what had changed. This could be solved by dumping the schema only, but this was impossible for our projects since our applications depended on certain data in the database to function. Eventually we returned to manually adding changes to the database dump.
Not only was this the simplest solution, but it also solved certain issues that some versions of MySQL have with exporting/importing. Normally we would have to dump the development database, remove any test data, log entries, etc, remove/change certain names where applicable and only then be able to create the production database. By manually adding changes we could control exactly what would end up in production, a little at a time, so that in the end everything was ready and moving to the production environment was as painless as possible.
How about versioning file generated by doing this:
mysqldump --no-data database > database.sql
Where I work we have an install script for each new version of the app which has the sql we need to run for the upgrade. This works well enough for 6 devs with some branching for maintenance releases. We're considering moving to Auto Patch http://autopatch.sourceforge.net/ which handles working out what patches to apply to any database you are upgrading. It looks like there may be some small complication handling branching with auto Patch, but it doesn't sound like that'll be an issue for you.
i'd guess, a batch file like this should do the job (didn't try tough) ...
mysqldump --no-data -ufoo -pbar dbname > path/to/app/schema.sql
svn commit path/to/app/schema.sql
just run the batch file after changing the schema, or let a cron/scheduler do it (but i don't know ... i think, commits work if just the timestamps changed, even if the contents is the same. don't know if that would be a problem.)
The main ideea is to have a folder with this structure in your project base path
/__DB
—-/changesets
——–/1123
—-/data
—-/tables
Now who the whole thing works is that you have 3 folders:
Tables
Holds the table create query. I recommend using the naming “table_name.sql”.
Data
Holds the table insert data query. I recommend using the same naming “table_name.sql”.
Note: Not all tables need a data file, you would only add the ones that need this initial data on project install.
Changesets
This is the main folder you will work with.
This holds the change sets made to the initial structure. This holds actually folders with changesets.
For example i added a folder 1123 wich will contain the modifications made in revision 1123 ( the number is from your code source control ) and may contain one or more sql files.
I like to add them grouped into tables with the naming xx_tablename.sql - the xx is a number that tells the order they need to be runned, since sometimes you need the modification runned in a certain order.
Note:
When you modify a table, you also add those modifications to table and data files … since those are the file s that will be used to do a fresh install.
This is the main ideea.
for more details you could check this blog post
Take a look at SchemaSync. It will generate the patch and revert scripts (.sql files) needed to migrate and version your database schema over time. It's a command line utility for MySQL that is language and framework independent.
Some months ago I searched tool for versioning MySQL schema. I found many useful tools, like Doctrine migration, RoR migration, some tools writen in Java and Python.
But no one of them was satisfied my requirements.
My requirements:
No requirements , exclude PHP and MySQL
No schema configuration files, like schema.yml in Doctrine
Able to read current schema from connection and create new migration script, than represent identical schema in other installations of application.
I started to write my migration tool, and today I have beta version.
Please, try it, if you have an interest in this topic.
Please send me future requests and bugreports.
Source code: bitbucket.org/idler/mmp/src
Overview in English: bitbucket.org/idler/mmp/wiki/Home
Overview in Russian: antonoff.info/development/mysql-migration-with-php-project
Our solution is MySQL Workbench. We regularly reverse-engineer the existing Database into a Model with the appropriate version number. It is then possible to easily perform Diffs between versions as needed. Plus, we get nice EER Diagrams, etc.
At our company we did it this way:
We put all tables / db objects in their own file, like tbl_Foo.sql. The files contain several "parts" that are delimited with
-- part: create
where create is just a descriptive identification for a given part, the file looks like:
-- part: create
IF not exists ...
CREATE TABLE tbl_Foo ...
-- part: addtimestamp
IF not exists ...
BEGIN
ALTER TABLE ...
END
Then we have an xml file that references every single part that we want executed when we update database to new schema.
It looks pretty much like this:
<playlist>
<classes>
<class name="table" desc="Table creation" />
<class name="schema" desc="Table optimization" />
</classes>
<dbschema>
<steps db="a_database">
<step file="tbl_Foo.sql" part="create" class="table" />
<step file="tbl_Bar.sql" part="create" class="table" />
</steps>
<steps db="a_database">
<step file="tbl_Foo.sql" part="addtimestamp" class="schema" />
</steps>
</dbschema>
</playlist>
The <classes/> part if for GUI, and <dbschema/> with <steps/> is to partition changes. The <step/>:s are executed sequentially. We have some other entities, like sqlclr to do different things like deploy binary files, but that's pretty much it.
Of course we have a component that takes that playlist file and a resource / filesystem object that crossreferences the playlist and takes out wanted parts and then runs them as admin on database.
Since the "parts" in .sql's are written so they can be executed on any version of DB, we can run all parts on every previous/older version of DB and modify it to be current.
Of course there are some cases where SQL server parses column names "early" and we have to later modify part's to become exec_sqls, but it doesn't happen often.
I think this question deserves a modern answer so I'm going to give it myself. When I wrote the question in 2009 I don't think Phinx already existed and most definitely Laravel didn't.
Today, the answer to this question is very clear: Write incremental DB migration scripts, each with an up and a down method and run all these scripts or a delta of them when installing or updating your app. And obviously add the migration scripts to your VCS.
As mentioned in the beginning, there are excellent tools today in the PHP world which help you manage your migrations easily. Laravel has DB migrations built-in including the respective shell commands. Everyone else has a similarly powerful framework agnostic solution with Phinx.
Both Artisan migrations (Laravel) and Phinx work the same. For every change in the DB, create a new migration, use plain SQL or the built-in query builder to write the up and down methods and run artisan migrate resp. phinx migrate in the console.
I do something similar to Manos except I have a 'master' file (master.sql) that I update with some regularity (once every 2 months). Then, for each change I build a version named .sql file with the changes. This way I can start off with the master.sql and add each version named .sql file until I get up to the current version and I can update clients using the version named .sql files to make things simpler.