oracle培訓講義(存儲版)
【正文】 212 physical reads 0 redo size 219216 bytes sent via SQL*Net to client 767 bytes received via SQL*Net from client 26 SQL*Net roundtrips to/from client 0 sorts (memory) 1 sorts (disk) 6219 rows processedSQL alter session set sort_area_size=1024。已選擇6219行。已選擇6219行。alter session set skip_unusable_indexes=true。SQL select from v$process a,v$session b 2 where = 3 and =userenv(39。Current：current reads。Disk：phisical reads(gets)。SQL conn sys/oracle as sysdbaSQL startup forceSQL grant dba to scoott。非歸檔模式，不需要把表設置為nologging，只要加上append提示，也會降低redo size的大小。會話已更改。會話已更改。已選擇6219行。第一種物理I/O，我們不能避免，如果在第一次查詢后，同樣的查詢還需要物理I/O,，則可能是因為data buffer cache太小，在物理內存足夠的情況下，可以把data buffer cache增大。已選擇6219行。表已丟棄。我們關注的是這兩個數(shù)量之和，即邏輯I/O的數(shù)量，邏輯I/O也代表了對緩存加上latch的數(shù)量，邏輯I/O越少，越好。EMP39。ENAME TEST SMITH 6ALLEN 6WARD 6JONES 6MARTIN 6BLAKE 6CLARK 6KING 6TURNER 6JAMES 6FORD 6MILLER 6已選擇12行。可以通過兩次同樣的查詢，驗證上述結論。set autotrace on statistics：只顯示統(tǒng)計信息。授權成功。授權成功。SQL create public synonym plan_table for plan_table。授權成功。SQL grant select on v_$session to plustrace。ENAME SAL SMITH 800ALLEN 1600WARD 1250JONES 2975MARTIN 1250BLAKE 2850CLARK 2450KING 5000TURNER 1500JAMES 950FORD 3000MILLER 1300已選擇12行。set autotrace traceonly explain：只顯示執(zhí)行計劃。 4 begin 5 select count(*) into l_t from dept。Statistics 284 recursive calls 0 db block gets 144 consistent gets 6 physical reads 136 redo size 579 bytes sent via SQL*Net to client 503 bytes received via SQL*Net from client 2 SQL*Net roundtrips to/from client 9 sorts (memory) 0 sorts (disk) 12 rows processedSQL /ENAME TEST SMITH 6ALLEN 6WARD 6JONES 6MARTIN 6BLAKE 6CLARK 6KING 6TURNER 6JAMES 6FORD 6MILLER 6已選擇12行。216。Array size：SQL conn system/oraclecatalog已連接。SQL select count(*) from t。Statistics 0 recursive calls 0 db block gets 853 consistent gets 0 physical reads 0 redo size 401094 bytes sent via SQL*Net to client 9050 bytes received via SQL*Net from client 779 SQL*Net roundtrips to/from client 0 sorts (memory) 0 sorts (disk) 6219 rows processedSQL set arraysize 16SQL /已選擇6219行。SQL show parameter workNAME TYPE VALUE
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