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select count(*) from mytable; |
Select * from mytables where myid>=1; 和 Select * from mytables where myid>=400000 |
SQL> select * from mytables where myid>=1; |
Execution Plan ---------------------------------------------------------- 0 SELECT STATEMENT Optimizer=CHOOSE (Cost=3132 Card=318474 Byt es=141402456) 1 0 TABLE ACCESS (FULL) OF 'MYTABLES' (Cost=3132 Card=318474 Byt es=141402456) Statistics ---------------------------------------------------------- 7 recursive calls 89 db block gets 41473 consistent gets 19828 physical reads 0 redo size 131489563 bytes sent via SQL*Net to client 1760245 bytes received via SQL*Net from client 21729 SQL*Net roundtrips to/from client 1 sorts (memory) 0 sorts (disk) 325917 rows processed |
Execution Plan ---------------------------------------------------------- 0 SELECT STATEMENT Optimizer=CHOOSE (Cost=346 Card=663 Bytes=2 94372) 1 0 TABLE ACCESS (BY INDEX ROWID) OF 'MYTABLES' (Cost=346 Card=663 Bytes=294372) 2 1 INDEX (RANGE SCAN) OF 'PK_MYTABLES' (UNIQUE) (Cost=5 Card=663) Statistics ---------------------------------------------------------- 1278 recursive calls 0 db block gets 6647 consistent gets 292 physical reads 0 redo size 3544898 bytes sent via SQL*Net to client 42640 bytes received via SQL*Net from client 524 SQL*Net roundtrips to/from client 1 sorts (memory) 0 sorts (disk) 7838 rows processed |
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