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這篇文章主要為大家展示了“Oracle 12CR2查詢(xún)轉(zhuǎn)換之星型轉(zhuǎn)換的方法”，內(nèi)容簡(jiǎn)而易懂，條理清晰，希望能夠幫助大家解決疑惑，下面讓小編帶領(lǐng)大家一起研究并學(xué)習(xí)一下“Oracle 12CR2查詢(xún)轉(zhuǎn)換之星型轉(zhuǎn)換的方法”這篇文章吧。
星型轉(zhuǎn)換是一種優(yōu)化轉(zhuǎn)換它用來(lái)避免對(duì)星型方案中的事實(shí)表進(jìn)行全表掃描。一個(gè)星型方案將數(shù)據(jù)分成事實(shí)與維度表。事實(shí)是對(duì)一個(gè)事件比如銷(xiāo)售的測(cè)量通常是數(shù)字。維度是標(biāo)識(shí)事實(shí)的分類(lèi)，比如日期，位置與產(chǎn)品。一個(gè)事實(shí)表有一個(gè)由方案中維度表主鍵所組成的復(fù)合鍵。維度表實(shí)際上充當(dāng)查找或引用表能讓你選擇你查詢(xún)所要請(qǐng)求的值。
星型轉(zhuǎn)換的目的
在連接事實(shí)表與維度表時(shí)，星型轉(zhuǎn)換可能避免對(duì)事實(shí)表執(zhí)行完全掃描。星型轉(zhuǎn)換通過(guò)只獲取連接到約束維度行記錄的相關(guān)事實(shí)行記錄來(lái)提高性能。在有些情況下，查詢(xún)已經(jīng)在維度表的其它列上有限制性過(guò)濾了。過(guò)濾組合可以大大減少數(shù)據(jù)庫(kù)從事實(shí)表中要處理的數(shù)據(jù)集大小。
星型轉(zhuǎn)換的工作原理
星型轉(zhuǎn)換增加了子查詢(xún)謂詞，叫作位圖半連接謂詞，關(guān)聯(lián)到約束維度表。當(dāng)在實(shí)際連接列上存在索引時(shí)優(yōu)化器執(zhí)行轉(zhuǎn)換。通過(guò)驅(qū)動(dòng)位圖and和or來(lái)操作由子查詢(xún)所提供的鍵值，數(shù)據(jù)庫(kù)只需要從事實(shí)表中檢索相關(guān)行記錄。如果維度表上的謂詞過(guò)濾掉了大量數(shù)據(jù)，那么星型轉(zhuǎn)換比對(duì)事實(shí)表完全掃描更有效。
在數(shù)據(jù)庫(kù)從事實(shí)表中檢索相關(guān)行記錄之后，數(shù)據(jù)庫(kù)可能需要使用原始謂詞連接這些行記錄回維度表。當(dāng)以下條件滿(mǎn)足時(shí)數(shù)據(jù)庫(kù)可以消除連接回維度表:
.維度表上的所有謂詞是半連接子查詢(xún)謂詞的一部分
.從子查詢(xún)中所選擇的列具有唯一性
.維度列不在select列，group by子句中等等
控制星型轉(zhuǎn)換
star_transformation_enabled參數(shù)控制著星型轉(zhuǎn)換。這個(gè)參數(shù)有以下參數(shù)值:
.true
優(yōu)化器通過(guò)自動(dòng)識(shí)別事實(shí)與約束維度表來(lái)執(zhí)行星型轉(zhuǎn)換。只有轉(zhuǎn)換后的執(zhí)行計(jì)劃成本比原始執(zhí)行計(jì)劃成本低時(shí)優(yōu)化器才執(zhí)行星型轉(zhuǎn)換。當(dāng)物化提高性能時(shí)優(yōu)化器也會(huì)嘗試臨時(shí)表轉(zhuǎn)換。
.false(缺省值)
優(yōu)化器不執(zhí)行星型轉(zhuǎn)換
.temp_disable
這個(gè)值與true相同，只是優(yōu)化器不會(huì)嘗試臨時(shí)表轉(zhuǎn)換
星型轉(zhuǎn)換:應(yīng)用場(chǎng)景
下面的查詢(xún)找出1999年Q1和Q2季度在California的所有城市中的總的網(wǎng)絡(luò)銷(xiāo)售額:
SELECT c.cust_city,
t.calendar_quarter_desc,
SUM(s.amount_sold) sales_amount
FROM sales s,
times t,
customers c,
channels ch
WHERE s.time_id = t.time_id
AND s.cust_id = c.cust_id
AND s.channel_id = ch.channel_id
AND c.cust_state_province = 'CA'
AND ch.channel_desc = 'Internet'
AND t.calendar_quarter_desc IN ('1999-01','1999-02')
GROUP BY c.cust_city, t.calendar_quarter_desc;示例輸出如下:
SQL> show parameter star_transformation_enabled
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
star_transformation_enabled string FALSE
SQL> SELECT c.cust_city,
2 t.calendar_quarter_desc,
3 SUM(s.amount_sold) sales_amount
4 FROM sales s,
5 times t,
6 customers c,
7 channels ch
8 WHERE s.time_id = t.time_id
9 AND s.cust_id = c.cust_id
10 AND s.channel_id = ch.channel_id
11 AND c.cust_state_province = 'CA'
12 AND ch.channel_desc = 'Internet'
13 AND t.calendar_quarter_desc IN ('1999-01','1999-02')
14 GROUP BY c.cust_city, t.calendar_quarter_desc;
CUST_CITY CALENDA SALES_AMOUNT
------------------------------ ------- ------------
Montara 1999-02 1618.01
Pala 1999-01 3263.93
Cloverdale 1999-01 52.64
Cloverdale 1999-02 266.28
San Francisco 1999-01 3058.27
San Mateo 1999-01 8754.59
Los Angeles 1999-01 1886.19
San Mateo 1999-02 21399.42
Pala 1999-02 936.62
El Sobrante 1999-02 3744.03
El Sobrante 1999-01 5392.34
Quartzhill 1999-01 987.3
Legrand 1999-01 26.32
Pescadero 1999-01 26.32
Arbuckle 1999-02 241.2
Quartzhill 1999-02 412.83
Montara 1999-01 289.07
Arbuckle 1999-01 270.08
San Francisco 1999-02 11257
Los Angeles 1999-02 2128.59
Pescadero 1999-02 298.44
Legrand 1999-02 18.66
22 rows selected.
SQL> select * from table(dbms_xplan.display_cursor(null,null,'advanced allstats last runstats_last peeked_binds'));
SQL_ID a069wzk60bbqd, child number 1
-------------------------------------
SELECT c.cust_city, t.calendar_quarter_desc, SUM(s.amount_sold)
sales_amount FROM sales s, times t, customers c, channels ch WHERE
s.time_id = t.time_id AND s.cust_id = c.cust_id AND s.channel_id =
ch.channel_id AND c.cust_state_province = 'CA' AND ch.channel_desc =
'Internet' AND t.calendar_quarter_desc IN ('1999-01','1999-02') GROUP
BY c.cust_city, t.calendar_quarter_desc
Plan hash value: 1865285285
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Starts | E-Rows |E-Bytes| Cost (%CPU)| E-Time | Pstart| Pstop | A-Rows | A-Time | Buffers | OMem | 1Mem | Used-Mem |
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | | | 957 (100)| | | | 22 |00:00:00.18 | 1812 | | | |
| 1 | HASH GROUP BY | | 1 | 22 | 1672 | 957 (2)| 00:00:01 | | | 22 |00:00:00.18 | 1812 | 1022K| 1022K| 1382K (0)|
|* 2 | HASH JOIN | | 1 | 138 | 10488 | 956 (2)| 00:00:01 | | | 964 |00:00:00.14 | 1812 | 1538K| 1538K| 1588K (0)|
| 3 | PART JOIN FILTER CREATE | :BF0000 | 1 | 183 | 2928 | 18 (0)| 00:00:01 | | | 181 |00:00:00.01 | 65 | | | |
|* 4 | TABLE ACCESS FULL | TIMES | 1 | 183 | 2928 | 18 (0)| 00:00:01 | | | 181 |00:00:00.01 | 65 | | | |
|* 5 | HASH JOIN | | 1 | 964 | 57840 | 938 (2)| 00:00:01 | | | 964 |00:00:00.11 | 1747 | 1448K| 1448K| 1521K (0)|
| 6 | MERGE JOIN CARTESIAN | | 1 | 3341 | 127K| 426 (1)| 00:00:01 | | | 3341 |00:00:00.02 | 1531 | | | |
|* 7 | TABLE ACCESS FULL | CHANNELS | 1 | 1 | 13 | 3 (0)| 00:00:01 | | | 1 |00:00:00.01 | 9 | | | |
| 8 | BUFFER SORT | | 1 | 3341 | 86866 | 423 (1)| 00:00:01 | | | 3341 |00:00:00.02 | 1522 | 178K| 178K| 158K (0)|
|* 9 | TABLE ACCESS FULL | CUSTOMERS | 1 | 3341 | 86866 | 423 (1)| 00:00:01 | | | 3341 |00:00:00.01 | 1522 | | | |
| 10 | PARTITION RANGE JOIN-FILTER| | 1 | 819K| 16M| 510 (2)| 00:00:01 |:BF0000|:BF0000| 118K|00:00:00.02 | 216 | | | |
| 11 | TABLE ACCESS FULL | SALES | 2 | 819K| 16M| 510 (2)| 00:00:01 |:BF0000|:BF0000| 118K|00:00:00.02 | 216 | | | |
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------從上面的執(zhí)行中可以看到，在沒(méi)有使用星型轉(zhuǎn)換時(shí)id=11，對(duì)表sales執(zhí)行的是全表掃描。在這個(gè)例子中，sales表是事實(shí)表，并且其它的表是維度表。sales表對(duì)于每一個(gè)銷(xiāo)售的產(chǎn)品都有一行記錄，因此它可以包含上十億行銷(xiāo)售記錄。然而，只有少量產(chǎn)品在指定的季度通過(guò)網(wǎng)絡(luò)銷(xiāo)售到了California的客戶(hù)手中。
使用星形轉(zhuǎn)換
SQL> alter session set star_transformation_enabled='true';
Session altered.
SQL> SELECT c.cust_city,
2 t.calendar_quarter_desc,
3 SUM(s.amount_sold) sales_amount
4 FROM sales s,
5 times t,
6 customers c,
7 channels ch
8 WHERE s.time_id = t.time_id
9 AND s.cust_id = c.cust_id
10 AND s.channel_id = ch.channel_id
11 AND c.cust_state_province = 'CA'
12 AND ch.channel_desc = 'Internet'
13 AND t.calendar_quarter_desc IN ('1999-01','1999-02')
14 GROUP BY c.cust_city, t.calendar_quarter_desc;
Montara 1999-02 1618.01
Pala 1999-01 3263.93
Cloverdale 1999-01 52.64
Cloverdale 1999-02 266.28
San Francisco 1999-01 3058.27
San Mateo 1999-01 8754.59
Los Angeles 1999-01 1886.19
San Mateo 1999-02 21399.42
Pala 1999-02 936.62
El Sobrante 1999-02 3744.03
El Sobrante 1999-01 5392.34
Quartzhill 1999-01 987.3
Legrand 1999-01 26.32
Pescadero 1999-01 26.32
Arbuckle 1999-02 241.2
Quartzhill 1999-02 412.83
Montara 1999-01 289.07
Arbuckle 1999-01 270.08
San Francisco 1999-02 11257
Los Angeles 1999-02 2128.59
Pescadero 1999-02 298.44
Legrand 1999-02 18.66
22 rows selected.從10053跟蹤文件中找到的星型轉(zhuǎn)換后的語(yǔ)句如下:
ST: Query after star xformation:******* UNPARSED QUERY IS ******* SELECT /*+ CACHE (T1) */ T1.C1 CUST_CITY, T.CALENDAR_QUARTER_DESC CALENDAR_QUARTER_DESC, SUM(S.AMOUNT_SOLD) SALES_AMOUNT FROM SH.SALES S, SH.TIMES T, SYS.SYS_TEMP_0FD9D6684_63D6F82 T1 WHERE S.CUST_ID = ANY (SELECT /*+ SEMIJOIN_DRIVER CACHE (T1) */ T1.C0 C0 FROM SYS.SYS_TEMP_0FD9D6684_63D6F82 T1) AND S.CHANNEL_ID = ANY (SELECT /*+ SEMIJOIN_DRIVER */ CH.CHANNEL_ID ITEM_1 FROM SH.CHANNELS CH WHERE CH.CHANNEL_DESC = 'Internet') AND S.TIME_ID = ANY (SELECT /*+ SEMIJOIN_DRIVER */ T.TIME_ID ITEM_1 FROM SH.TIMES T WHERE T.CALENDAR_QUARTER_DESC = '1999-01' OR T.CALENDAR_QUARTER_DESC = '1999-02') AND S.TIME_ID = T.TIME_ID AND S.CUST_ID = T1.C0 AND (T.CALENDAR_QUARTER_DESC = '1999-01' OR T.CALENDAR_QUARTER_DESC = '1999-02') GROUP BY T1.C1, T.CALENDAR_QUARTER_DESC
其執(zhí)行計(jì)劃如下:
SQL> select * from table(dbms_xplan.display_cursor(null,null,'advanced allstats last runstats_last peeked_binds'));
SQL_ID a069wzk60bbqd, child number 3
-------------------------------------
SELECT c.cust_city, t.calendar_quarter_desc, SUM(s.amount_sold)
sales_amount FROM sales s, times t, customers c, channels ch WHERE
s.time_id = t.time_id AND s.cust_id = c.cust_id AND s.channel_id =
ch.channel_id AND c.cust_state_province = 'CA' AND ch.channel_desc =
'Internet' AND t.calendar_quarter_desc IN ('1999-01','1999-02') GROUP
BY c.cust_city, t.calendar_quarter_desc
Plan hash value: 2164696140
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Starts | E-Rows |E-Bytes| Cost (%CPU)| E-Time | Pstart| Pstop | A-Rows | A-Time | Buffers | Reads | Writes | OMem | 1Mem | Used-Mem |
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | | | 573 (100)| | | | 22 |00:00:01.41 | 9083 | 96 | 10 | | | |
| 1 | TEMP TABLE TRANSFORMATION | | 1 | | | | | | | 22 |00:00:01.41 | 9083 | 96 | 10 | | | |
| 2 | LOAD AS SELECT | SYS_TEMP_0FD9D667F_63D6F82 | 1 | | | | | | | 0 |00:00:01.07 | 1539 | 2 | 10 | 1042K| 1042K| |
|* 3 | TABLE ACCESS FULL | CUSTOMERS | 1 | 383 | 9958 | 423 (1)| 00:00:01 | | | 3341 |00:00:00.01 | 1522 | 0 | 0 | | | |
| 4 | HASH GROUP BY | | 1 | 542 | 30894 | 150 (1)| 00:00:01 | | | 22 |00:00:00.33 | 7538 | 93 | 0 | 1022K| 1022K| 1346K (0)|
|* 5 | HASH JOIN | | 1 | 1681 | 95817 | 149 (0)| 00:00:01 | | | 964 |00:00:00.31 | 7538 | 93 | 0 | 1572K| 1572K| 1677K (0)|
| 6 | TABLE ACCESS FULL | SYS_TEMP_0FD9D667F_63D6F82 | 1 | 383 | 5745 | 2 (0)| 00:00:01 | | | 3341 |00:00:00.01 | 18 | 10 | 0 | | | |
|* 7 | HASH JOIN | | 1 | 1681 | 70602 | 147 (0)| 00:00:01 | | | 964 |00:00:00.29 | 7520 | 83 | 0 | 1538K| 1538K| 1686K (0)|
|* 8 | TABLE ACCESS FULL | TIMES | 1 | 183 | 2928 | 18 (0)| 00:00:01 | | | 181 |00:00:00.01 | 65 | 0 | 0 | | | |
| 9 | VIEW | VW_ST_A3F94988 | 1 | 1685 | 43810 | 129 (0)| 00:00:01 | | | 964 |00:00:00.23 | 7455 | 83 | 0 | | | |
| 10 | NESTED LOOPS | | 1 | 1685 | 96045 | 106 (0)| 00:00:01 | | | 964 |00:00:00.23 | 7455 | 83 | 0 | | | |
| 11 | PARTITION RANGE SUBQUERY | | 1 | 1684 | 47167 | 52 (0)| 00:00:01 |KEY(SQ)|KEY(SQ)| 964 |00:00:00.22 | 7271 | 83 | 0 | | | |
| 12 | BITMAP CONVERSION TO ROWIDS| | 2 | 1684 | 47167 | 52 (0)| 00:00:01 | | | 964 |00:00:00.21 | 7204 | 83 | 0 | | | |
| 13 | BITMAP AND | | 2 | | | | | | | 2 |00:00:00.21 | 7204 | 83 | 0 | | | |
| 14 | BITMAP MERGE | | 2 | | | | | | | 2 |00:00:00.05 | 15 | 10 | 0 | 1024K| 512K| 4096 (0)|
| 15 | BITMAP KEY ITERATION | | 2 | | | | | | | 2 |00:00:00.04 | 15 | 10 | 0 | | | |
| 16 | BUFFER SORT | | 2 | | | | | | | 2 |00:00:00.01 | 9 | 0 | 0 | 73728 | 73728 | |
|* 17 | TABLE ACCESS FULL | CHANNELS | 1 | 1 | 13 | 3 (0)| 00:00:01 | | | 1 |00:00:00.01 | 9 | 0 | 0 | | | |
|* 18 | BITMAP INDEX RANGE SCAN| SALES_CHANNEL_BIX | 2 | | | | |KEY(SQ)|KEY(SQ)| 2 |00:00:00.04 | 6 | 10 | 0 | | | |
| 19 | BITMAP MERGE | | 2 | | | | | | | 2 |00:00:00.03 | 445 | 10 | 0 | 1024K| 512K|39936 (0)|
| 20 | BITMAP KEY ITERATION | | 2 | | | | | | | 181 |00:00:00.02 | 445 | 10 | 0 | | | |
| 21 | BUFFER SORT | | 2 | | | | | | | 362 |00:00:00.01 | 65 | 0 | 0 | 73728 | 73728 | |
|* 22 | TABLE ACCESS FULL | TIMES | 1 | 183 | 2928 | 18 (0)| 00:00:01 | | | 181 |00:00:00.01 | 65 | 0 | 0 | | | |
|* 23 | BITMAP INDEX RANGE SCAN| SALES_TIME_BIX | 362 | | | | |KEY(SQ)|KEY(SQ)| 181 |00:00:00.01 | 380 | 10 | 0 | | | |
| 24 | BITMAP MERGE | | 2 | | | | | | | 2 |00:00:00.14 | 6744 | 63 | 0 | 1024K| 512K|45056 (0)|
| 25 | BITMAP KEY ITERATION | | 2 | | | | | | | 403 |00:00:00.14 | 6744 | 63 | 0 | | | |
| 26 | BUFFER SORT | | 2 | | | | | | | 6682 |00:00:00.01 | 18 | 0 | 0 | 5512K| 964K| 174K (0)|
| 27 | TABLE ACCESS FULL | SYS_TEMP_0FD9D667F_63D6F82 | 1 | 383 | 1915 | 2 (0)| 00:00:01 | | | 3341 |00:00:00.01 | 18 | 0 | 0 | | | |
|* 28 | BITMAP INDEX RANGE SCAN| SALES_CUST_BIX | 6682 | | | | |KEY(SQ)|KEY(SQ)| 403 |00:00:00.10 | 6726 | 63 | 0 | | | |
| 29 | TABLE ACCESS BY USER ROWID | SALES | 964 | 1 | 29 | 77 (2)| 00:00:01 | ROWID | ROWID | 964 |00:00:00.01 | 184 | 0 | 0 | | | |
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Query Block Name / Object Alias (identified by operation id):
-------------------------------------------------------------
1 - SEL$D5EF7599
2 - SEL$F6045C7B
3 - SEL$F6045C7B / C@SEL$F6045C7B
6 - SEL$D5EF7599 / T1@SEL$9C741BEB
8 - SEL$D5EF7599 / T@SEL$1
9 - SEL$5E9A798F / VW_ST_A3F94988@SEL$D5EF7599
10 - SEL$5E9A798F
12 - SEL$5E9A798F / S@SEL$1
17 - SEL$6EE793B7 / CH@SEL$6EE793B7
22 - SEL$ACF30367 / T@SEL$ACF30367
27 - SEL$E1F9C76C / T1@SEL$E1F9C76C
29 - SEL$5E9A798F / SYS_CP_S@SEL$5E9A798F
Outline Data
-------------
/*+
BEGIN_OUTLINE_DATA
IGNORE_OPTIM_EMBEDDED_HINTS
OPTIMIZER_FEATURES_ENABLE('12.2.0.1')
DB_VERSION('12.2.0.1')
OPT_PARAM('star_transformation_enabled' 'true')
ALL_ROWS
NO_PARALLEL
OUTLINE_LEAF(@"SEL$F6045C7B")
OUTLINE_LEAF(@"SEL$ACF30367")
OUTLINE_LEAF(@"SEL$6EE793B7")
OUTLINE_LEAF(@"SEL$E1F9C76C")
OUTLINE_LEAF(@"SEL$5E9A798F")
TABLE_LOOKUP_BY_NL(@"SEL$0E028FD0" "S"@"SEL$1")
OUTLINE_LEAF(@"SEL$D5EF7599")
OUTLINE(@"SEL$1")
OUTLINE(@"SEL$0E028FD0")
OUTLINE(@"SEL$C3AF6D21")
ELIMINATE_JOIN(@"SEL$1" "CH"@"SEL$1")
OUTLINE(@"SEL$5208623C")
STAR_TRANSFORMATION(@"SEL$1" "S"@"SEL$1" SUBQUERIES(("T"@"SEL$1") ("CH"@"SEL$1") TEMP_TABLE("C"@"SEL$1")))
FULL(@"SEL$D5EF7599" "T"@"SEL$1")
NO_ACCESS(@"SEL$D5EF7599" "VW_ST_A3F94988"@"SEL$D5EF7599")
FULL(@"SEL$D5EF7599" "T1"@"SEL$9C741BEB")
LEADING(@"SEL$D5EF7599" "T"@"SEL$1" "VW_ST_A3F94988"@"SEL$D5EF7599" "T1"@"SEL$9C741BEB")
USE_HASH(@"SEL$D5EF7599" "VW_ST_A3F94988"@"SEL$D5EF7599")
USE_HASH(@"SEL$D5EF7599" "T1"@"SEL$9C741BEB")
SWAP_JOIN_INPUTS(@"SEL$D5EF7599" "T1"@"SEL$9C741BEB")
USE_HASH_AGGREGATION(@"SEL$D5EF7599")
BITMAP_AND(@"SEL$5E9A798F" "S"@"SEL$1" ("SALES"."CHANNEL_ID") 1)
BITMAP_AND(@"SEL$5E9A798F" "S"@"SEL$1" ("SALES"."TIME_ID") 2)
BITMAP_AND(@"SEL$5E9A798F" "S"@"SEL$1" ("SALES"."CUST_ID") 3)
ROWID(@"SEL$5E9A798F" "SYS_CP_S"@"SEL$5E9A798F")
LEADING(@"SEL$5E9A798F" "S"@"SEL$1" "SYS_CP_S"@"SEL$5E9A798F")
SUBQUERY_PRUNING(@"SEL$5E9A798F" "S"@"SEL$1" PARTITION)
USE_NL(@"SEL$5E9A798F" "SYS_CP_S"@"SEL$5E9A798F")
FULL(@"SEL$E1F9C76C" "T1"@"SEL$E1F9C76C")
SEMIJOIN_DRIVER(@"SEL$E1F9C76C")
FULL(@"SEL$6EE793B7" "CH"@"SEL$6EE793B7")
SEMIJOIN_DRIVER(@"SEL$6EE793B7")
FULL(@"SEL$ACF30367" "T"@"SEL$ACF30367")
SEMIJOIN_DRIVER(@"SEL$ACF30367")
FULL(@"SEL$F6045C7B" "C"@"SEL$F6045C7B")
SEMIJOIN_DRIVER(@"SEL$F6045C7B")
END_OUTLINE_DATA
*/
Predicate Information (identified by operation id):
---------------------------------------------------
3 - filter("C"."CUST_STATE_PROVINCE"='CA')
5 - access("ITEM_1"="C0")
7 - access("ITEM_2"="T"."TIME_ID")
8 - filter(("T"."CALENDAR_QUARTER_DESC"='1999-01' OR "T"."CALENDAR_QUARTER_DESC"='1999-02'))
17 - filter("CH"."CHANNEL_DESC"='Internet')
18 - access("S"."CHANNEL_ID"="CH"."CHANNEL_ID")
22 - filter(("T"."CALENDAR_QUARTER_DESC"='1999-01' OR "T"."CALENDAR_QUARTER_DESC"='1999-02'))
23 - access("S"."TIME_ID"="T"."TIME_ID")
28 - access("S"."CUST_ID"="C0")
Column Projection Information (identified by operation id):
-----------------------------------------------------------
1 - "C1"[VARCHAR2,30], "T"."CALENDAR_QUARTER_DESC"[CHARACTER,7], SUM("ITEM_3")[22]
2 - SYSDEF[4], SYSDEF[0], SYSDEF[1], SYSDEF[120], SYSDEF[0]
3 - "C"."CUST_ID"[NUMBER,22], "C"."CUST_CITY"[VARCHAR2,30], "C"."CUST_STATE_PROVINCE"[VARCHAR2,40]
4 - "C1"[VARCHAR2,30], "T"."CALENDAR_QUARTER_DESC"[CHARACTER,7], SUM("ITEM_3")[22]
5 - (#keys=1; rowset=256) "C0"[NUMBER,22], "ITEM_1"[NUMBER,22], "C1"[VARCHAR2,30], "T"."TIME_ID"[DATE,7], "ITEM_2"[DATE,7], "T"."CALENDAR_QUARTER_DESC"[CHARACTER,7], "ITEM_3"[NUMBER,22]
6 - (rowset=256) "C0"[NUMBER,22], "C1"[VARCHAR2,30]
7 - (#keys=1; rowset=256) "T"."TIME_ID"[DATE,7], "ITEM_2"[DATE,7], "T"."CALENDAR_QUARTER_DESC"[CHARACTER,7], "ITEM_1"[NUMBER,22], "ITEM_3"[NUMBER,22]
8 - (rowset=256) "T"."TIME_ID"[DATE,7], "T"."CALENDAR_QUARTER_DESC"[CHARACTER,7]
9 - "ITEM_1"[NUMBER,22], "ITEM_2"[DATE,7], "ITEM_3"[NUMBER,22]
10 - ROWID[ROWID,10], ROWID[ROWID,10], "S"."CUST_ID"[NUMBER,22], "S"."TIME_ID"[DATE,7], "S"."AMOUNT_SOLD"[NUMBER,22]
11 - ROWID[ROWID,10]
12 - ROWID[ROWID,10]
13 - STRDEF[BM VAR, 10], STRDEF[BM VAR, 10], STRDEF[BM VAR, 32496]
14 - STRDEF[BM VAR, 10], STRDEF[BM VAR, 10], STRDEF[BM VAR, 32496]
15 - STRDEF[10], STRDEF[10], STRDEF[7920], "S"."CHANNEL_ID"[NUMBER,22]
16 - (#keys=2) "CH"."CHANNEL_ID"[NUMBER,22], "CH"."CHANNEL_DESC"[VARCHAR2,20]
17 - (rowset=256) "CH"."CHANNEL_ID"[NUMBER,22], "CH"."CHANNEL_DESC"[VARCHAR2,20]
18 - STRDEF[BM VAR, 10], STRDEF[BM VAR, 10], STRDEF[BM VAR, 7920], "S"."CHANNEL_ID"[NUMBER,22]
19 - STRDEF[BM VAR, 10], STRDEF[BM VAR, 10], STRDEF[BM VAR, 32496]
20 - STRDEF[10], STRDEF[10], STRDEF[7920], "S"."TIME_ID"[DATE,7]
21 - (#keys=2) "T"."TIME_ID"[DATE,7], "T"."CALENDAR_QUARTER_DESC"[CHARACTER,7]
22 - (rowset=256) "T"."TIME_ID"[DATE,7], "T"."CALENDAR_QUARTER_DESC"[CHARACTER,7]
23 - STRDEF[BM VAR, 10], STRDEF[BM VAR, 10], STRDEF[BM VAR, 7920], "S"."TIME_ID"[DATE,7]
24 - STRDEF[BM VAR, 10], STRDEF[BM VAR, 10], STRDEF[BM VAR, 32496]
25 - STRDEF[10], STRDEF[10], STRDEF[7920], "S"."CUST_ID"[NUMBER,22]
26 - (#keys=1) "C0"[NUMBER,22]
27 - (rowset=256) "C0"[NUMBER,22]
28 - STRDEF[BM VAR, 10], STRDEF[BM VAR, 10], STRDEF[BM VAR, 7920], "S"."CUST_ID"[NUMBER,22]
29 - ROWID[ROWID,10], "S"."CUST_ID"[NUMBER,22], "S"."TIME_ID"[DATE,7], "S"."AMOUNT_SOLD"[NUMBER,22]
Note
-----
- automatic DOP: Computed Degree of Parallelism is 1 because of parallel threshold
- cbqt star transformation used for this statement
- this is an adaptive plan從Note部分的cbqt star transformation used for this statement信息可知執(zhí)行了星型轉(zhuǎn)換，從執(zhí)行計(jì)劃中的ID=29這個(gè)步驟可知對(duì)表sales使用了索引掃描而不是全表掃描。對(duì)于子查詢(xún)中的times(第22行),customers(第3行),channels（第17行）表中的每個(gè)鍵值，數(shù)據(jù)庫(kù)使用事實(shí)表sales(第23,28,18行)上索引檢索位圖。
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