A transaction profile question - block growth always groups of 5?

I've been doing some transaction profiles of a custom app. I use the monitoring facility which is turned on before the transaction. Also, before this the entire database is analyzed with compute option.

So, after this one transaction.. I go this on a particular table from the monitoring..

20 inserts on oneofmytables.

Also, comparing the statistics on this table before and after (re-calculated after transaction)..

I get this:

Row count change : +20 (makes sense)
Block count change: +5 (seems a little high.. I'll explain) Total bytes for table: 1,520 increase
Avg size of row: 76 .. unchanged.

Block size is 4K
Pct Free and Pct Used are Oracle defaults.. even so..
Under what cirumstances would an increase of 1,520 bytes ask for 5 blocks?

Now, I've heard that things are often increased in groups of 5 blocks.. So is this true? 5 block boundaries?
(this is 8.1.5 on AIX 4.3.3)

If that's the case.. how about example B: monitoring results: 1101 inserts 8 updates... Different table:
Row count change : +1101
block count change: +39 (not a multiple of 5) Total bytes for table: 132,120 increase
Avg size of row: 120 .. unchanged.

So in this case, did it get 40 blocks for the inserts and put one back on the freelist after the updates which probably shrunk some of the rows?

Thanks in advance,
D Received on Wed May 02 2001 - 23:55:50 CDT