I am using Kendo gantt widget to display Tasks for a project, unlike the simple task module that is in Telerik documentation where a task has a title, start, end date.
My tasks are rather heavy and include many other fields, so I want to optimize the process of retrieving these task in a way that if the database has not been updated, then I get the same tasks from the session, and if the database has been updated, then
I make a query and call latest from the database.
Looking at the following code:
privatestaticboolUpdateDatabase=false;
and
publicvirtualIList<TaskViewModel>GetAll(){var result =HttpContext.Current.Session["GanttTasks"]asIList<TaskViewModel>;if(result ==null||UpdateDatabase){
result = db.GanttTasks.ToList().Select(task =>newTaskViewModel{TaskID= task.ID,Title= task.Title,Start=DateTime.SpecifyKind(task.Start,DateTimeKind.Utc),End=DateTime.SpecifyKind(task.End,DateTimeKind.Utc),ParentID= task.ParentID,PercentComplete= task.PercentComplete,OrderId= task.OrderID,Expanded= task.Expanded,Summary= task.Summary}).ToList();HttpContext.Current.Session["GanttTasks"]= result;}return result;
The issue I am facing is that my application is multi-tenant meaning different user some might belong to the same tenant and others could belong to different tenants will be using application simultaneously, there for the static variable is out of question.
my question is what is the best way to optimize in such case, should I save the update database in a session and use it instead of the static variable, therefore it be user aware of that particular user activity if he update or not the db, how this will perform
if say 200 users are logged at the same time, is there another way you might know or suggest for such case.
should I save the update database in a session and use it instead of the static variable, therefore it be user aware of that particular user activity if he update or not the db, how this will perform if say 200 users are logged at the same time, is there another
way you might know or suggest for such case.
The database is the system of record. Storing data in Session creates a greater chance of concurrency issues and stale data. Whether caching data in Session poses an issue in your design is unknown. The community cannot see your design but most importantly
the Kendo Gantt chart is a Telerik control. You need Telerik support.
Lets imagine same scenario without Telerik widget , it is just an example of a single get call to the database that gathers complex data. if the session stores user specific data, can you explain how the risk of concurrency in this case will occur.?
I understand that i shared a limited code example, i am not asking for a full evaluation of the problem. rather than someone to share a link or point out an example of best practices to cache or optimize in a multi-tenant architecture similar to this scenario.
Lets imagine same scenario without Telerik widget , it is just an example of a single get call to the database that gathers complex data. if the session stores user specific data, can you explain how the risk of concurrency in this case will occur.?
If the data only belongs to the user and no other uses can change the data then caching the data in Session is fine. The code becomes a bit more complex due to syncing between Session and the data store.
If other users can affect the data then the problem becomes more complex as you'll to handle concurrency. A distributed cache might be a better approach.
You could include the tenant id in a "key" so that you have a dedicated cache for each tenant (if this is your question). Caching is harder for frequently updated data (at worst you need to reload often which kind of defeat keeping data in cache). My first
move here would be likely to make sure there is no optimization possible (all users in a tenant are seeing all tasks right away ?).
When caching it's likely best to start by frequently used read only data if possible.
session is a per user cache, but it sounds like you need a per tenant cache. The issue with caches is when to invalidate. You can use a cache with a database dependency notification.
Or you could add a cache table to the database keyed by tenant (and whatever else is required). the cache table can just have a json column with the data. you can use database triggers to update the cache (or just delete it).
Thanks for your response, the tasks are accessed by different users under one tenant, as you suggested I need to cache by tenant, which makes it a bit more complected, as such any user could alter / edit the data. so maybe not a good idea to cache data if
not read only.
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Retrieving data from session instead of a database query
Jul 28, 2020 10:50 AM|tree123|LINK
I am using Kendo gantt widget to display Tasks for a project, unlike the simple task module that is in Telerik documentation where a task has a title, start, end date.
My tasks are rather heavy and include many other fields, so I want to optimize the process of retrieving these task in a way that if the database has not been updated, then I get the same tasks from the session, and if the database has been updated, then I make a query and call latest from the database.
Looking at the following code:
and
The issue I am facing is that my application is multi-tenant meaning different user some might belong to the same tenant and others could belong to different tenants will be using application simultaneously, there for the static variable is out of question. my question is what is the best way to optimize in such case, should I save the update database in a session and use it instead of the static variable, therefore it be user aware of that particular user activity if he update or not the db, how this will perform if say 200 users are logged at the same time, is there another way you might know or suggest for such case.
Thanks
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Re: Retrieving data from session instead of a database query
Jul 28, 2020 11:09 AM|mgebhard|LINK
The database is the system of record. Storing data in Session creates a greater chance of concurrency issues and stale data. Whether caching data in Session poses an issue in your design is unknown. The community cannot see your design but most importantly the Kendo Gantt chart is a Telerik control. You need Telerik support.
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0 Points
4 Posts
Re: Retrieving data from session instead of a database query
Jul 28, 2020 11:36 AM|tree123|LINK
thanks mgebhard for your response,
Lets imagine same scenario without Telerik widget , it is just an example of a single get call to the database that gathers complex data. if the session stores user specific data, can you explain how the risk of concurrency in this case will occur.?
I understand that i shared a limited code example, i am not asking for a full evaluation of the problem. rather than someone to share a link or point out an example of best practices to cache or optimize in a multi-tenant architecture similar to this scenario.
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49171 Points
21755 Posts
Re: Retrieving data from session instead of a database query
Jul 28, 2020 12:17 PM|mgebhard|LINK
If the data only belongs to the user and no other uses can change the data then caching the data in Session is fine. The code becomes a bit more complex due to syncing between Session and the data store.
If other users can affect the data then the problem becomes more complex as you'll to handle concurrency. A distributed cache might be a better approach.
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Re: Retrieving data from session instead of a database query
Jul 28, 2020 01:06 PM|PatriceSc|LINK
You could include the tenant id in a "key" so that you have a dedicated cache for each tenant (if this is your question). Caching is harder for frequently updated data (at worst you need to reload often which kind of defeat keeping data in cache). My first move here would be likely to make sure there is no optimization possible (all users in a tenant are seeing all tasks right away ?).
When caching it's likely best to start by frequently used read only data if possible.
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Re: Retrieving data from session instead of a database query
Jul 28, 2020 03:41 PM|bruce (sqlwork.com)|LINK
session is a per user cache, but it sounds like you need a per tenant cache. The issue with caches is when to invalidate. You can use a cache with a database dependency notification.
https://docs.microsoft.com/en-us/aspnet/web-forms/overview/data-access/caching-data/using-sql-cache-dependencies-cs
Or you could add a cache table to the database keyed by tenant (and whatever else is required). the cache table can just have a json column with the data. you can use database triggers to update the cache (or just delete it).
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Re: Retrieving data from session instead of a database query
Aug 08, 2020 01:25 PM|tree123|LINK
Thanks for your response, the tasks are accessed by different users under one tenant, as you suggested I need to cache by tenant, which makes it a bit more complected, as such any user could alter / edit the data. so maybe not a good idea to cache data if not read only.