oracle绑定变量测试及性能对比

1.创建测试数据

2.查看cursor_sharing的值

SQL> show parameter cursor_sharing;

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
cursor_sharing                       string      EXACT

3.打开SQL追踪

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.执行语句块（使用绑定变量）

SQL> begin
  2  for x in 1..10000 loop
  3  execute immediate 'select * from monkey.testtable where id=:x' using x;
  4  end loop;
  5  end;
  6  /

5.关闭SQL追踪

SQL> alter session set sql_trace=false;

Session altered.

6.格式化trace文件

$ cd /oracle/diag/rdbms/monkey/monkey/trace/
$ tkprof monkey_ora_26356.trc out.txt
$ more out.txt

7.结果

select *
from
 monkey.testtable where id=: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，包括執行產生的遞歸和非遞歸類SQL，總共解析了5次，花費了0.22秒

8.执行语句块（不适用绑定变量）

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.结果

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採樣
..............................................
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，包括執行產生的遞歸和非遞歸類SQL，總共解析了20002次，花費了21.4秒