我们的程序员抱怨一段执行很慢的程序，我把代码执行分析执行计划，
后果如下：
这是最初的执行效果及执行计划
SQL> SELECT "SP_TRANS"."TRANS_NO",
2 "SP_TRANS_SUB"."ITEM_CODE",
3 "SP_ITEM"."ITEM_NAME",
4 "SP_ITEM"."CHART_ID",
5 "SP_ITEM"."SPECIFICATION",
6 "SP_TRANS_SUB"."COUNTRY",
7 "SP_TRANS_SUB"."QTY",
8 "SP_TRANS_SUB"."PRICE",
9 "SP_TRANS"."VENDOR_CODE",
10 "SP_TRANS"."PAY_MODE",
11 NVL("SP_TRANS_SUB"."PAY_QTY",0),
12 0 as PAY_THIS
13 FROM "SP_ITEM",
14 "SP_TRANS_SUB",
15 "SP_TRANS"
16 WHERE ( "SP_TRANS_SUB"."TRANS_NO" = "SP_TRANS"."TRANS_NO" ) and
17 ( "SP_ITEM"."ITEM_CODE" = "SP_TRANS_SUB"."ITEM_CODE" ) and
18 ( ( "SP_TRANS"."VENDOR_CODE" = '20011021023') )
19 /
8 rows selected.
Elapsed: 00: 00: 00.51
Execution Plan
----------------------------------------------------------
0 SELECT STATEMENT Optimizer=CHOOSE
1 0 NESTED LOOPS
2 1 NESTED LOOPS
3 2 TABLE access (FULL) OF 'SP_TRANS'
4 2 TABLE ACCESS (BY INDEX ROWID) OF 'SP_TRANS_SUB'
5 4 INDEX (RANGE SCAN) OF 'PK_SP_TRANS_SUB' (UNIQUE)
6 1 TABLE ACCESS (BY INDEX ROWID) OF 'SP_ITEM'
7 6 INDEX (UNIQUE SCAN) OF 'PK_SP_ITEM' (UNIQUE)
Statistics
----------------------------------------------------------
0 recursive calls
4 db block gets
323 consistent gets
0 physical reads
0 redo size
1809 bytes sent via SQL*Net to client
425 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
8 rows processed
此前这几个表都没有分析过。
然后我analyze相关表
SQL> analyze table sp_trans_sub compute statistics;
Table analyzed.
Elapsed: 00: 00: 30.64
SQL> SELECT "SP_TRANS"."TRANS_NO",
2 "SP_TRANS_SUB"."ITEM_CODE",
3 "SP_ITEM"."ITEM_NAME",
4 "SP_ITEM"."CHART_ID",
5 "SP_ITEM"."SPECIFICATION",
6 "SP_TRANS_SUB"."COUNTRY",
7 "SP_TRANS_SUB"."QTY",
8 "SP_TRANS_SUB"."PRICE",
9 "SP_TRANS"."VENDOR_CODE",
10 "SP_TRANS"."PAY_MODE",
11 NVL("SP_TRANS_SUB"."PAY_QTY",0),
12 0 as PAY_THIS
13 FROM "SP_ITEM",
14 "SP_TRANS_SUB",
15 "SP_TRANS"
16 WHERE ( "SP_TRANS_SUB"."TRANS_NO" = "SP_TRANS"."TRANS_NO" ) and
17 ( "SP_ITEM"."ITEM_CODE" = "SP_TRANS_SUB"."ITEM_CODE" ) and
18 ( ( "SP_TRANS"."VENDOR_CODE" = '20011021023') )
19 /
8 rows selected.
Elapsed: 00: 00: 06.49
Execution Plan
----------------------------------------------------------
0 SELECT STATEMENT Optimizer=CHOOSE (Cost=18577 Card=126726520
Bytes=30034185240)
1 0 MERGE JOIN (Cost=18577 Card=126726520 Bytes=30034185240)
2 1 SORT (JOIN) (Cost=14722 Card=310300 Bytes=20790100)
3 2 HASH JOIN (Cost=358 Card=310300 Bytes=20790100)
4 3 TABLE ACCESS (FULL) OF 'SP_TRANS' (Cost=43 Card=229
Bytes=8473)
5 3 TABLE ACCESS (FULL) OF 'SP_TRANS_SUB' (Cost=158 Card
=135502 Bytes=4065060)
6 1 SORT (JOIN) (Cost=3855 Card=40840 Bytes=6942800)
7 6 TABLE ACCESS (FULL) OF 'SP_ITEM' (Cost=77 Card=40840 B
ytes=6942800)
Statistics
----------------------------------------------------------
150 recursive calls
89 db block gets
1837 consistent gets
755 physical reads
60 redo size
1732 bytes sent via SQL*Net to client
425 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
4 sorts (memory)
1 sorts (disk)
8 rows processed
SQL>
SQL> analyze table sp_trans compute statistics;
Table analyzed.
Elapsed: 00: 00: 13.00
SQL>
SQL> SELECT "SP_TRANS"."TRANS_NO",
2 "SP_TRANS_SUB"."ITEM_CODE",
3 "SP_ITEM"."ITEM_NAME",
4 "SP_ITEM"."CHART_ID",
5 "SP_ITEM"."SPECIFICATION",
6 "SP_TRANS_SUB"."COUNTRY",
7 "SP_TRANS_SUB"."QTY",
8 "SP_TRANS_SUB"."PRICE",
9 "SP_TRANS"."VENDOR_CODE",
10 "SP_TRANS"."PAY_MODE",
11 NVL("SP_TRANS_SUB"."PAY_QTY",0),
12 0 as PAY_THIS
13 FROM "SP_ITEM",
14 "SP_TRANS_SUB",
15 "SP_TRANS"
16 WHERE ( "SP_TRANS_SUB"."TRANS_NO" = "SP_TRANS"."TRANS_NO" ) and
17 ( "SP_ITEM"."ITEM_CODE" = "SP_TRANS_SUB"."ITEM_CODE" ) and
18 ( ( "SP_TRANS"."VENDOR_CODE" = '20011021023') )
19 /
8 rows selected.
Elapsed: 00: 00: 01.62
Execution Plan
----------------------------------------------------------
0 SELECT STATEMENT Optimizer=CHOOSE (Cost=1453 Card=447198 Byt
es=101066748)
1 0 NESTED LOOPS (Cost=1453 Card=447198 Bytes=101066748)
2 1 HASH JOIN (Cost=358 Card=1095 Bytes=61320)
3 2 TABLE ACCESS (FULL) OF 'SP_TRANS' (Cost=43 Card=273 By
tes=7098)
4 2 TABLE ACCESS (FULL) OF 'SP_TRANS_SUB' (Cost=158 Card=1
35502 Bytes=4065060)
5 1 TABLE ACCESS (BY INDEX ROWID) OF 'SP_ITEM' (Cost=1 Card=
40840 Bytes=6942800)
6 5 INDEX (UNIQUE SCAN) OF 'PK_SP_ITEM' (UNIQUE)
Statistics
----------------------------------------------------------
0 recursive calls
8 db block gets
1344 consistent gets
0 physical reads
0 redo size
1824 bytes sent via SQL*Net to client
425 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
3 sorts (memory)
0 sorts (disk)
8 rows processed
SQL>
SQL> analyze table sp_item compute statistics
2 /
Table analyzed.
Elapsed: 00: 00: 11.67
SQL> SELECT "SP_TRANS"."TRANS_NO",
2 "SP_TRANS_SUB"."ITEM_CODE",
3 "SP_ITEM"."ITEM_NAME",
4 "SP_ITEM"."CHART_ID",
5 "SP_ITEM"."SPECIFICATION",
6 "SP_TRANS_SUB"."COUNTRY",
7 "SP_TRANS_SUB"."QTY",
8 "SP_TRANS_SUB"."PRICE",
9 "SP_TRANS"."VENDOR_CODE",
10 "SP_TRANS"."PAY_MODE",
11 NVL("SP_TRANS_SUB"."PAY_QTY",0),
12 0 as PAY_THIS
13 FROM "SP_ITEM",
14 "SP_TRANS_SUB",
15 "SP_TRANS"
16 WHERE ( "SP_TRANS_SUB"."TRANS_NO" = "SP_TRANS"."TRANS_NO" ) and
17 ( "SP_ITEM"."ITEM_CODE" = "SP_TRANS_SUB"."ITEM_CODE" ) and
18 ( ( "SP_TRANS"."VENDOR_CODE" = '20011021023') )
19 /
8 rows selected.
Elapsed: 00: 00: 01.43
Execution Plan
----------------------------------------------------------
0 SELECT STATEMENT Optimizer=CHOOSE (Cost=687 Card=1362 Bytes=
128028)
1 0 HASH JOIN (Cost=687 Card=1362 Bytes=128028)
2 1 HASH JOIN (Cost=358 Card=1362 Bytes=76272)
3 2 TABLE ACCESS (FULL) OF 'SP_TRANS' (Cost=43 Card=273 By
tes=7098)
4 2 TABLE ACCESS (FULL) OF 'SP_TRANS_SUB' (Cost=158 Card=1
35502 Bytes=4065060)
5 1 TABLE ACCESS (FULL) OF 'SP_ITEM' (Cost=77 Card=29547 Byt
es=1122786)
Statistics
----------------------------------------------------------
0 recursive calls
12 db block gets
1820 consistent gets
0 physical reads
0 redo size
1732 bytes sent via SQL*Net to client
425 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
3 sorts (memory) right">（出处：清风软件下载学院）
