Quick way to set background color of cells in DayPilotScheduler

The BeforeCellRender event is fired for every cell and it needs to be kept as efficient as possible. It is not possible to run a new database query in every invocation.

I recommend running a single query (e.g. in Page_Load) to get all the necessary data and storing the result in a special property of the WebForm page. In BeforeCellRender, only perform a simple in-memory lookup (within the data).

HI Dan. Thanks for getting back to me. What I did was to create a simple datatable with three columns (resource ID, date and 1 or 0 to denote working day) and store that in memory, then in the BeforeCellRender event I run a select query on the datatable for resourceID and date, but that is still incredibly slow as there's tens of thousands of cells to populate. I just wondered if it possible at all to approach this in a more efficient way.

You can try to measure where the time is spent:

1. Database query and datatable creation.
2. Lookup. Instead of a datatable, it would be faster to use a hashtable with something like "resource_date" as a key. Searching an in-memory datatable with 70,000 rows can still take some time, especially if you repeat it 70,000 times.
3. Sending the data to the client. The data for 70,000 cells also need to be sent to the client side. The Scheduler tries to compress this data but the compression is based on finding rows/columns with same values which may not be your case. It will take some time to send this data to the client. You can try enabling gzip HTTP compression to make the transport faster.