I have a laravel app running and a master slave implementation. the master is used for writing and the slave is used for reading. However how do we work with sessions if we write to session table and grab from sessions table right after user is logged in? Is there anyway we can make certain read requests to the master instead?
If I inderstood the question right, you could use the DB::on method described in: Specifying The Query Connection
Related
I want to use dynamic databases on runtime without effecting config/database.php because of concurrent users.
I have a main db with a table that contains reference to several other dbs. Now at runtime I need to not only connect to those dbs but also may want to run migrations on them.
I am aware that this is possible by having a second connection entry in config.database.connections but I have a feeling that if two users hit the server at the same time, the physical config file changes may create a conflict.
I also read (and also experimented) that you can edit the second connection using below code at runtime:
\Config::set('database.connections.mysql2.database', 'somedynamicdb');
DB::purge('mysql2');
But I fear that if it persists changes for different users, then it may conflict for concurrent users. And if it does not persist changes, then it wont work for migrations.
I want to understand/know two things specifically:
What is the scope of this above code (i.e. Config::set() call)? Does it persist over different user calls to the server?
If I call migrations using Artisan::call('migrate') with a --database=connectionname clause, right after I change the db name in connectionname, will that use the dynamically set database or the physical config value?
UPDATE
Also worth noting that a call to Artisan::call('migrate') with a --database=connectionname, will make the new connection persist for the rest of your app call.
See here for details:
https://github.com/laravel/framework/issues/28253
Config::set will only apply for the request for which it was set, won't apply to any other requests, and will not persist beyond the request. If you're not processing a request (e.g. a CLI command) then it won't affect anything beyond the current PHP process.
As for Item #2, if you're invoking from the command line, you can just do DB_CONNECTION=connectionname php artisan migrate. If you need to invoke the artisan command from code, using Config::set is still the right way to go.
We use connection created on the fly here all time and works very well. We setup this on Middleware that we included after authentication and is only valid on the user current user request based on login information.
How can I get job details from its ID, ex: 866FvqTxVVvi4PmCo7kHmD7u7bHaxCdn
got that id from queue:listen, thanks
There isn't a built in way of doing this through Laravel. It entirely depends upon which queue driver you are using.
For example, if you are using Redis then you would need to use the Redis CLI to search through the database for the appropriate task.
I'm seeing an error with some Laravel code that uses an AWS RDS database. The code writes a record to the database and then immediately does a search to load that record using the primary key and gets no results.
If I try it manually afterwards I find the record. If I insert a 1-second sleep in the code it works correctly.
I've tried this using Laravel's separate settings for read and write hosts. I've also tried setting them to the same host and only using one host. The result is always the same. However other environments with the same configuration do not have the error.
Is there an option in RDS that needs to be changed to have the record available immediately after it's written.
The error is due to the mySQL master-slave replication lag.
A common mistake is to use a mySQL cluster and then perform a read
immediately after a write.
Since the read occurs on one of the slave/read hosts and the write occurs on the master, the data would not be replicated at the time of the read.
There are a couple of ways to rectify the error:
The read immediately after must be performed on the master (not the slave). Even though you've mentioned that you changed it to a single host, often people make a mistake while switching the connection. Refer this SO post to properly switch connections in Laravel
An easier way may be to use the sticky database option in Laravel. Beware: this may cause performance issues if not used carefully for only the use case you desire. From the docs:
The sticky option is an optional value that can be used to allow the
immediate reading of records that have been written to the database
during the current request cycle.
If the sticky option is enabled and a "write" operation has been
performed against the database during the current request cycle, any
further "read" operations will use the "write" connection.
The most "non-obvious" way is to NOT perform a read immediately after a write. Think about whether this can be avoided depending on your use case.
Other methods: refer this SO post
I have a web service that calls some stored procedure on a AS400 via JTOpen.
What I would like to do is that the connections used to call the stored procedures was opened in a specific subsystem with a specific user, instead of qusrwrk/quser as now (default).
I think I can be able to clone the qusrwrk subsystem to make it start with a specific user, but what I cannot figure out is the mechanism to open the connection in the specific subsystem.
I guess there should be a property at connection level to say subsystem=MySubsystem.
But unfortunatly I haven't found that property.
Any hint would be appreciated.
Flavio
Let the system take care of the subsystem the job database server job is started in.
You should just focus on the application (which is what IBM i excels in).
If need be, you can tweak subsystem parameters for QUSRWRK to improve performance by allocating memory, etc.
The system uses a pool of prestarted jobs as described in the FAQ: When I do WRKACTJOB, why is the host server job running under QUSER instead of the profile specified on the AS400 object?
To improve performance, the host server jobs are prestarted jobs running under QUSER. When the Toolbox connects to a host server job in order to perform an API call, run a command, etc, a request is sent from the Toolbox to an available prestarted job. This request includes the user profile specified on the AS400 object that represents the connection. The host server job receives the request and swaps to the specified user profile before it runs the request. The host server itself originally runs under the QUSER profile, so output from the WRKACTJOB command will show the job as being owned by QUSER. However, the job is in fact running under the profile specified on the request. To determine what profile is being used for any given host server job, you can do one of three things:
1. Display the job log for that job and find the message indicating which user profile is used as a result of the swap.
2. Work with the job and display job status attributes to view the current user profile.
3. Use Navigator for i to view all of the server jobs, which will list the current user of each job. You can also use Navigator for i to look at the server jobs being used by a particular user.
In a workflow there are sessions connected in parallel and in sequence. Suppose some sessions which are in parallel and in sequential mode are failed, How do I restart the workflow with only failed sessions. How can I design this in Informatica?
Turn 'suspend on error' for workflow
Turn 'restart on recovery' for each session in workflow
Now if any session fail workflow will be suspended until you fix the problem and hit recover on workflow in monitor. When you do so it cause to restart only failed sessions.
A large publishing client asked us to implement something similar to what you asked. We crated a database table to keep track of successful sessions within a workflow. Each session will have a mapping at the end that adds an entry to database which says I passed or failed. When we try to run in a recovery mode we query the database at the beginning of each session to find out if we need to run this session or not.
We also provided a web interface to this table where business users can manually choose which session to run or escape based on their needs.
Recovery option will work only if you have "workflow recovery" turned on in repository. If you dont, then you can check option "fail workflow if task fails" at individual session level and create condition on link that connect workflow to each other. Disadvantage of this method is that your workflow will appear failed and wont execute next sessions until failed one are fixed.
thanks.