This will be a short blog post but I hope still interesting one as I will provide example how to set per table retention in Log Analytics. Several weeks ago the Azure Monitor team has provided option to set retention period per table instead of just having retention period for the whole workspace.
Update 17.10.2019: If you set per table retention you will not be able to delete the workspace. You will get web request error 500 when you try that in the portal. To delete the workspace you will have to reset the value for every table with tool like ARM client. Example with Perf table below:
ARMClient.exe put "/subscriptions/22391568-8971-4320-b4be-08beb4919e9a/resourcegroups/loganalytics/providers/microsoft.operationalinsights/workspaces/ws000001/tables/Perf?api-version=2015-03-20" "{'properties':{'retentionInDays':null}}"
Update 17.10.2019: Just a few hours later Azure Monitor team fixed the issue. That is what I call fast support. Kudos to Azure Monitor team for being such proactive.