mark wrote:
> Guys,
> I am get confused with number of blocks read in FTS. The HWM is 58 blocks,
> but the FTS reads much, much more blocks.
> Why is that?
>
> The sqlplus output:
>
> SQL> analyze table klient compute statistics for table;
> SQL> select blocks from user_tables where table_name='KLIENT';
>
> BLOCKS
> ----------
> 58
>
> SQL> set autotr on exp stat
> SQL> select * from klient;
> ...
>
> Plan wykonywania
> ----------------------------------------------------------
> 0 SELECT STATEMENT Optimizer=ALL_ROWS (Cost=14 Card=16384 Byte
> s=344064)
>
> 1 0 TABLE ACCESS (FULL) OF 'KLIENT' (TABLE) (Cost=14 Card=1638
> 4 Bytes=344064)
>
> Statystyki
> ----------------------------------------------------------
> 158 recursive calls
> 0 db block gets
> 1171 consistent gets
> 0 physical reads
> 0 redo size
> 514940 bytes sent via SQL*Net to client
> 12524 bytes received via SQL*Net from client
> 1094 SQL*Net roundtrips to/from client
> 4 sorts (memory)
> 0 sorts (disk)
> 16384 rows processed
>
>
The consistent gets are due to the recursive calls which are the work oracle has
to do to parse the query. Run the query twice and the consistent gets should drop
significantly.
Received on Wed Feb 16 2005 - 11:17:10 CST
