**：hlu
test:本次實驗的環境是10.101.50.35開啟兩個session，乙個sid為138，乙個為135
connected to oracle database 10g enterprise edition release 10.2.0.4.0
connected as bsderp
sql>
sql> alter system flush shared_pool;
system altered
sql> set erveroutput on;
cannot set erveroutput
sql> set timing on;
sql> declare
2 type rc is ref cursor;
3 l_rc rc;
4 l_dummy all_objects.object_name%type;
5 l_start number default dbms_utility.get_time;
6 begin
7 for i in 1 .. 1000 loop
8 open l_rc for 'select object_name from all_objects where object_id = '||i;
通常寫法
9 fetch l_rc into l_dummy;
10 close l_rc;
11 end loop;
12 dbms_output.put_line(round((dbms_utility.get_time-l_start)/100,2)|| 'seconds ...');
13 end;
14 /
pl/sql procedure successfully completed
executed in 24.547 seconds
執行時間
sql>
sql>
sql>
sql>
sql> declare
2 type rc is ref cursor;
3 l_rc rc;
4 l_dummy all_objects.object_name%type;
5 l_start number default dbms_utility.get_time;
6 begin
7 for i in 1 .. 1000 loop
8 open l_rc for 'select object_name from all_objects where object_id = :x' using i;
繫結變數
9 fetch l_rc into l_dummy;
10 close l_rc;
11 end loop;
12 dbms_output.put_line(round((dbms_utility.get_time-l_start)/100,2)|| 'seconds ...');
13 end;
14 /
pl/sql procedure successfully completed
executed in 0.25 seconds
執行時間
可以和普通的寫法比較下，看看差別是多少倍
參考：上面同樣目的的兩條sql執行後對於軟硬解析的影響：
/**解釋一下v$sesstat中相關取值的重要概念
1 > opened cursors current (當前單個session開啟的cursors數量)
2 > parse count (hard) (當前session硬解析次數)
3 > parse count (total) (當前session解析總次數)
4 > session cursor cache count (設定session_cached_cursors引數後,"相同"sql被解析3次後被cache在session cursor cache中的數量
5 > session cursor cache hits (軟軟解析的次數 a "softer" soft parse )
6 > 手工計算一下軟解析次數parse count (total) - session cursor cache hits - parse count (hard) = parse count(soft)
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