How does flyway decide order of execution for sql scripts.
I have attached a screenshot of scripts I have in my project in various directories; but it executed it in different order than I expected. Also, the execution order varies if I ran the scripts in incremental manner or all at the same time.
Here's the order I expected them to execute in.
Here's the order they got executed in.
I am using flyway-core 4.0.3 with sprint boot. I have set flyway.out-of-order=true.
Flyway ignores leading zeroes between dots and that's why the order was different than what I expected. Once I removed leading zeroes; the scripts were executed in order I expected.
Related
I use flyway 8.5.0 and I want that my beforeMigrate or my afterMigrate sql is reported in the history table. Is this feaseable? or is there any config to setup this?
Then an other question: my repetable only runs when they change (checksum) but for my understanding the repetible sql should run every time. not so?
The beforeMigrate and afterMigrate SQL wont appear in your history table. If you look at the tutorial example for callbacks you can see that beforeMigrate can be called before the schema history table is created which would cause issues if it was trying to add itself to it. Additionally, I'm assuming these will be mostly static executions and would not really be part of the version history.
https://flywaydb.org/documentation/tutorials/callbacks
For repeatable, no they are only applied when the checksum has changed.
Repeatable migrations are very useful for managing database objects whose definition can then simply be maintained in a single file in version control. Instead of being run just once, they are (re-)applied every time their checksum changes.
https://flywaydb.org/documentation/tutorials/repeatable
Some teams in our company are currently "upgrading" some legacy projects to use Flyway. One problem is that there exists multiple installations with already available database objects (baseline).
We currently have (and definitely will have more in the future as well) a use case, where we have to create some new migration scripts, but they only should run when certain conditions about the current state of the database are met.
For example: run this script, but only if table X in the database contains data Y
I have already seend Flyway conditional db migration, but to me this doesn't seem like the right solution, since the condition isn't just some static environment. The condition if a migration should be executed or not should be dependent on the current live state of the database.
I myself have not much experience with Flyway, but more with Liquibase. There I would implement it like this:
<preConditions onFail="WARN">
<sqlCheck expectedResult="0">select count(*) from oldtable</sqlCheck>
</preConditions>
Is there an equivalent in Flyway?
To my knowledge, no, Flyway itself can't do this kind of conditional statement. However, since flyway just runs the scripts in order, put the conditional command within the deployment script and that will work. Flyway simply executes the scripts, so they can be customized as you need them to be.
I have installed Flyway Software and trying to deploy code. I have a Scenario
I created a file V1_01_CREATE_TABLE.SQL to create a table.
Created a file V1_01_CREATE_PACKAGE.SQL - This package will hold code to insert a row into one of the columns in table created in step 1.
Created a file V1_01_02_ALTER_TABLE.SQL - This SQL will rename the column which was being referred in step2.
This will invalidate the package if I run 1, 2 & 3. How does FLYWAY handle such a situation? Does it understand object dependency?
As explained in the manual, Flyway simply passes your SQL scripts to the database to be executed, and records the success or failure of their execution.
Flyway has no interest or understanding of the content of your scripts. Flyway never looks at the content of those scripts. In that sense, there is no “intelligence” in Flyway.
Flyway is like the postal worker delivering your letters without opening the envelope. You are the author, and you take full responsibility for the logic and correctness of the SQL scripts. You are responsible for following the naming conventions so your scripts run in the correct order.
After initially creating its metadata table, Flyway makes very limited use of JDBC and SQL. Flyway does little more than make a connection to the database server, determine which of the scripts have yet to be run, and say to the database “Here, run this script, and this script, and then run this script.” while recording the success or failure of each run.
You should name your scripts in order they needs to be executed
V1.0.0_CREATE_TABLE.SQL
V1.0.1_CREATE_PACKAGE.SQL
V1.0.2_ALTER_TABLE.SQL
This will execute scripts in migrated
I am currently using the Flyway Command Line tool to manage our scripts which will be invoked via our release process triggered from our CI Build server.
The issue is I have 274 repeatable migrations covering package specs, package bodies, functions, procedures, views and materialised views.
When I run migrate everything works as expected with migrations executing followed by any changed repeatable migrations but lets say in the next release we want to delete a object which one of the repeatable migrations maintains. For example, we want to remove the repeatable script that defined ProcedureOne (ie R__ProcedureOne.sql).
To do this I would have a new migration script (V3.1.5.1.01__DropProcedureOne.sql) but I would also remove the repeatable migration script so the object isn't created again and maintained.
However, executing flyway info shows the R__ProcedureOne.sql script with the status of MISSING.
While I agree it is missing it is a deliberate action to have it deleted as it is no longer required opposed to being misplaced.
I am aware of the migrate option ignoreMissingMigrations but i think using this introduces risk and could mask genuine missing files.
What is the general guidance on how best to remove a repeatable scripts?
I suggest that you simply keep the file but make it empty (ie zero bytes). Alternatively have a comment in the file that explains that the object it represents has been removed.
As for actually removing it, another option from what you suggested could be to update the repeatable migration to remove itself then update again to zero length. This has the advantage of being able to be replayed into an empty database; since repeatable migrations are applied after versioned the procedure in your example won't exist to be dropped. The disadvantage is running two migrations.
I am trying flyway for first time, evaluating how it will fit into our project.
Trying to understand how a Failed Scenario will work
Naturally, what i did next was, modified the sql script, and re tried running, but got checksum error
Have three Ques here
So I guess the only way out is ... need to make a 1.2 with correct format or manually modify 'schema_version' table. Right , or am i missing something?
Wondering how will such a scenario work in case if this script is called from continuous integration tools (Jenkins or Bamboo). Manual Intervention will be needed.
Not sure if some other tool like Liquibase will behave in a different (better) manner
In that situation I think you should use "flyway repair" rather the "flyway migrate"
https://flywaydb.org/documentation/command/repair
One thing from your post that is not clear is was the script you ran a single DDL statement or a number of statements, of which one or more failed?. The reason for asking is that flyway records the results of a migration, but does not itself clean up 'script errors'. Depending on the database you are using this could be done by running the DDL statements within a transaction.
Liquibased operates with a much tighter connection to the database as it directly interacts with the DDL that can be expressed in a range of different formats. As such it has a much tighter control over the management of DDL deployment.
Upstream insists on manual rolling back of failed migration and re-applying it again. There is no "skip" command.
But you can manually fix and complete failed migration and manually change "schema_version"."success" to 1.