Do we need to take any kind of backup when changing database recovery model from SIMPLE-->BULK LOGGED-->SIMPLE
My first question would be why you're changing the recovery model to bulk-logged for a short period.
If you want to initialise the log chain so that you can take log backups, you need to take a full or diff backup after switching to bulk-logged, but the fact that you're switching back to simple suggests you don't want log backups, so I fail to see the point of changing to bulk logged.
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: Discussions on DB performance with occasional diversions into recoverability
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