oracle繫結變數測試及效能對比
阿新 • • 發佈：2020-08-11
1.建立測試資料
2.檢視cursor_sharing的值
SQL> show parameter cursor_sharing; NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ cursor_sharing string EXACT
3.開啟SQL追蹤
SQL> alter session set sql_trace=true; Session altered. SQL> select value from v$diag_info where name='Default Trace File'; VALUE -------------------------------------------------------------------------------- /oracle/diag/rdbms/monkey/monkey/trace/monkey_ora_26356.trc
4.執行語句塊（使用繫結變數）
SQL> begin 2 for x in 1..10000 loop 3 executeimmediate 'select * from monkey.testtable where id=:x' using x; 4 end loop; 5 end; 6 /
5.關閉SQL追蹤
SQL> alter session set sql_trace=false; Session altered.
6.格式化trace檔案
$ cd /oracle/diag/rdbms/monkey/monkey/trace/ $ tkprof monkey_ora_26356.trc out.txt $ more out.txt
7.結果
select * from monkey.testtable whereid=:x call count cpu elapsed disk query current rows ------- ------ -------- ---------- ---------- ---------- ---------- ---------- Parse 1 0.00 0.00 0 0 0 0 Execute 10000 0.03 0.03 0 1 0 0 Fetch 0 0.00 0.00 0 0 0 0 ------- ------ -------- ---------- ---------- ---------- ---------- ---------- total 10001 0.03 0.03 0 1 0 0 Misses in library cache during parse: 1 Optimizer mode: ALL_ROWS Parsing user id: SYS (recursive depth: 1) Number of plan statistics captured: 1 OVERALL TOTALS FOR ALL NON-RECURSIVE STATEMENTS call count cpu elapsed disk query current rows ------- ------ -------- ---------- ---------- ---------- ---------- ---------- Parse 3 0.00 0.01 0 0 0 0 Execute 4 0.16 0.16 0 0 0 1 Fetch 2 0.00 0.01 0 0 0 1 ------- ------ -------- ---------- ---------- ---------- ---------- ---------- total 9 0.16 0.19 0 0 0 2 Misses in library cache during parse: 3 Misses in library cache during execute: 1 OVERALL TOTALS FOR ALL RECURSIVE STATEMENTS call count cpu elapsed disk query current rows ------- ------ -------- ---------- ---------- ---------- ---------- ---------- Parse 2 0.00 0.00 0 0 0 0 Execute 10001 0.03 0.03 0 1 0 0 Fetch 1 0.00 0.00 0 75 0 1 ------- ------ -------- ---------- ---------- ---------- ---------- ---------- total 10004 0.03 0.03 0 76 0 1
從最後的整體統計可以看到，包括執行產生的遞迴和非遞迴類SQL，總共解析了5次，花費了0.22秒
8.執行語句塊（不適用繫結變數）
SQL> begin 2 for x in 1..10000 loop 3 execute immediate 'select * from monkey.testtable where id ='||x; 4 end loop; 5 end; 6 /
9.結果
select * from monkey.testtable where id =1 call count cpu elapsed disk query current rows ------- ------ -------- ---------- ---------- ---------- ---------- ---------- Parse 1 0.00 0.00 0 1 0 0 Execute 1 0.00 0.00 0 0 0 0 Fetch 0 0.00 0.00 0 0 0 0 ------- ------ -------- ---------- ---------- ---------- ---------- ---------- total 2 0.00 0.00 0 1 0 0 Misses in library cache during parse: 1 Optimizer mode: ALL_ROWS Parsing user id: SYS (recursive depth: 1) Number of plan statistics captured: 1 SQL ID: 2q3s22f8bw5wx Plan Hash: 2994338341 SELECT /* OPT_DYN_SAMP */ /*+ ALL_ROWS IGNORE_WHERE_CLAUSE NO_PARALLEL(SAMPLESUB) opt_param('parallel_execution_enabled', 'false') NO_PARALLEL_INDEX(SAMPLESUB) NO_SQL_TUNE */ NVL(SUM(C1),0), NVL(SUM(C2),0) FROM (SELECT /*+ IGNORE_WHERE_CLAUSE NO_PARALLEL("TESTTABLE") FULL("TESTTABLE") NO_PARALLEL_INDEX("TESTTABLE") */ 1 AS C1, CASE WHEN "TESTTABLE"."ID"=2 THEN 1 ELSE 0 END AS C2 FROM "monkey"."TESTTABLE" SAMPLE BLOCK (1.065089 , 1) SEED (1) "TESTTABLE") SAMPLESUB call count cpu elapsed disk query current rows ------- ------ -------- ---------- ---------- ---------- ---------- ---------- Parse 1 0.00 0.00 0 0 0 0 Execute 1 0.00 0.00 0 0 0 0 Fetch 1 0.00 0.00 0 75 0 1 ------- ------ -------- ---------- ---------- ---------- ---------- ---------- total 3 0.00 0.00 0 75 0 1 select * from monkey.testtable where id =2 call count cpu elapsed disk query current rows ------- ------ -------- ---------- ---------- ---------- ---------- ---------- Parse 1 0.00 0.00 0 1 0 0 Execute 1 0.00 0.00 0 0 0 0 Fetch 0 0.00 0.00 0 0 0 0 ------- ------ -------- ---------- ---------- ---------- ---------- ---------- total 2 0.00 0.00 0 1 0 0 Misses in library cache during parse: 1 Optimizer mode: ALL_ROWS Parsing user id: SYS (recursive depth: 1) Number of plan statistics captured: 1 select * from monkey.testtable where id =3 call count cpu elapsed disk query current rows ------- ------ -------- ---------- ---------- ---------- ---------- ---------- Parse 1 0.00 0.00 0 1 0 0 Execute 1 0.00 0.00 0 0 0 0 Fetch 0 0.00 0.00 0 0 0 0 ------- ------ -------- ---------- ---------- ---------- ---------- ---------- total 2 0.00 0.00 0 1 0 0 Misses in library cache during parse: 1 Optimizer mode: ALL_ROWS Parsing user id: SYS (recursive depth: 1) Number of plan statistics captured: 1 總這裡可以看到，每一個值都解析了一遍，並且每一個值都要對表進行取樣 .............................................. select * from monkey.testtable where id =10000 call count cpu elapsed disk query current rows ------- ------ -------- ---------- ---------- ---------- ---------- ---------- Parse 1 0.00 0.00 0 1 0 0 Execute 1 0.00 0.00 0 0 0 0 Fetch 0 0.00 0.00 0 0 0 0 ------- ------ -------- ---------- ---------- ---------- ---------- ---------- total 2 0.00 0.00 0 1 0 0 Misses in library cache during parse: 1 Optimizer mode: ALL_ROWS Parsing user id: SYS (recursive depth: 1) Number of plan statistics captured: 1 OVERALL TOTALS FOR ALL NON-RECURSIVE STATEMENTS call count cpu elapsed disk query current rows ------- ------ -------- ---------- ---------- ---------- ---------- ---------- Parse 2 0.00 0.00 0 0 0 0 Execute 3 0.69 0.70 0 0 0 1 Fetch 2 0.00 0.02 0 0 0 1 ------- ------ -------- ---------- ---------- ---------- ---------- ---------- total 7 0.69 0.72 0 0 0 2 Misses in library cache during parse: 1 Misses in library cache during execute: 1 OVERALL TOTALS FOR ALL RECURSIVE STATEMENTS call count cpu elapsed disk query current rows ------- ------ -------- ---------- ---------- ---------- ---------- ---------- Parse 20000 9.86 9.91 0 10000 0 0 Execute 20000 0.19 0.16 0 0 0 0 Fetch 10000 10.60 10.60 0 750000 0 10000 ------- ------ -------- ---------- ---------- ---------- ---------- ---------- total 50000 20.65 20.68 0 760000 0 10000
從最後的整體統計可以看到，包括執行產生的遞迴和非遞迴類SQL，總共解析了20002次，花費了21.4秒