User quotas on tablespace

Question

Hi,
I created a tablespace and made it default to a user. immediateley i issued a command to apply a quota 0m for that user to that tablespace.Now when i am trying to create a table by logging on that newley created user and inserting the table on that tablespace i am able to do that no error. can any one say why it is happening? if i repeated the inserting operation after some time i get the error message of quota full.remember that i have already inserted arround 10000 of rows on that table which has only 2 columns on it.
thx
pradeep

Answer 1

This is entirely expected behaviour. Setting a quota of zero means 'you may not consume space... and if you already have consumed space before, you may not consume any extra space'. It does not mean 'you cannot insert data into objects which already have space assigned to them'.
In other words, creating a table causes an extent to be allocated. The table thus acquires some space (say, 1MB). You can think of that as your user 'consuming' or using up 1MB of space in the tablespace. You THEN set quota to zero. That means that table still exists; it's still allowed to be its (say) 1MB; but it can never acquire any **extra** space.
So now you start inserting rows into that table -of course you're not going to get any errors, because you aren't asking the table to grow. You're simply filling up the 1MB that your table had already acquired when it was legal for it to do so. Eventually, however, you will fill up the initial extent and your next insert will cause the table to want to acquire a new extent -which it is not allowed to do because of the Quota 0 setting. At that point, you'll get the error.
I see you've had some not-very-helpful replies in this thread already. Well, Daljit of course won't be able to replicate the behaviour you see, because in his example, he is trying to create a new table: that immediately seeks to acquire an initial extent; it's thus immediately trying to consume fresh space in the tablespace; it therefore immediately fails. The thing he didn't test properly was doing INSERTs when quota is zero: those will work fine, until one insert causes the table to want to extend.
Similarly, since nothing is going wrong, it's pointless you worrying about whether it's a role or privilege thing. It's doubly pointless because quota enforcement has never had anything whatsoever to do with roles or privileges, with the sole exception of having unlimited quota via a grant of a particular system privilege (which we know can't be an issue here, since eventually the quota is being enforced).
And, just for once, the repeated calls from others for your Oracle version are irrelevant: quotas have behaved this way since at least version 8.0, and quite possibly version 7 before that (but I have trouble remembering that far back with any certainty).
I think we see in some of the replies to this thread that you are not alone in not knowing properly how quotas actually work!