I would like to know what really happens when deletes and updates occur
inside of a data block. I have a table with a single extent and 2555
rows( Initrans 5, Pctused 10, Pctfree 1 - the reason being that the
rows will be inserted and subsequently deleted - no updates ).
When the rows are inserted for the first time, 180 rows can be packed
into each block( avg rowlen 20,db_block_size 4096, block_overhead 302).
Every subsequent delete( deletes all 2555 rows - not truncate )and
insert( inserts 2555 rows ) causes lesser number of rows(176) to be
placed in each block. This keeps decreasing to 170 and remains stable
henceforth.
1. I would like to know why this data space decreases and if so where
does the data space go - Does the block overhead increase? If so why?
2. Also, does an increase in the Initrans( and hence the itl slots in
the row directory in the Row header )affect the data space? I think it
does.
I would still like to confirm it.
(And byw I know what initrans and maxtrans are - I know that an itl slot
takes up 23 bytes - but that does not answer my question.)
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Received on Fri Jun 18 1999 - 11:03:18 CDT
