Amazon restrict access to the SYS user within AWS instances for safety and security reasons – the safety aspect being that users cannot be trusted to not cause self-harm!
Wishing to increase or add a datafile to a tablespace is not allowed directly and you have to use the API “rdsadmin.rdsadmin_util” to manage this and other functions.
These functions are listed in here and a further page provides some good examples
One little workaround which I found useful and have used in the past on ‘on-premise’ databases is to use the ‘alter tablespace TS1 resize 50G;’ format which is quite useful if it is a bigfile tablespace and therefore only has one datafile. In that way you do not have to specify a file name or use the ‘ALTER DATAFILE’ format which is restricted by AWS.
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