これらのテーブルのフィールドは20未満で、プロパティの行数は約900万行、リストの行数は300万行ですが、これは問題にはなりません。これがデータベースの目的です...
Listing_idsのタイプはNumberです。これまでのところ、プロパティテーブルには実際にはリストを指していないlistingidを持つ行が600万行あるため、Oracleは存在しないリストを探すのに多くの時間を費やしていると推測されます。それも意味がありますか？
Select count(*)
from listings.rfs_listings listings
join listings.rfs_properties properties
on listings.listing_id= properties.listing_id
where listings.display = 1
and properties.city= 'New York'
and rownum <= 10;
クエリに対してExplainPlanを実行し、次の情報を取得しました。
PLAN_TABLE_OUTPUT
Plan hash value: 772088252
-------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
-------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 10 | 4110 | 283 (0)| 00:00:04 |
|* 1 | COUNT STOPKEY | | | | | |
| 2 | NESTED LOOPS | | | | | |
| 3 | NESTED LOOPS | | 10 | 4110 | 283 (0)| 00:00:04 |
|* 4 | TABLE ACCESS FULL | RFS_LISTINGS | 140 | 2940 | 3 (0)| 00:00:01 |
|* 5 | INDEX UNIQUE SCAN | RFS_PROPERTIES_LD730_UNIQUE | 1 | | 1 (0)| 00:00:01 |
|* 6 | TABLE ACCESS BY INDEX ROWID| RFS_PROPERTIES | 1 | 390 | 2 (0)| 00:00:01 |
-------------------------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter(ROWNUM<=10)
4 - filter("LISTINGS"."DISPLAY"=1)
5 - access("LISTINGS"."LISTING_ID"="PROPERTIES"."LISTING_ID")
6 - filter(NLSSORT("PROPERTIES"."CITY",'nls_sort=''BINARY_CI''')=HEXTORAW('6E657720796F726
B00') )
編集：テーブルスキーマ：
rfs.rfs_listings:
Name Null? Type
------------------------------- -------- ------------------
DETAIL_ID NOT NULL NUMBER
LISTING_ID NOT NULL NUMBER
DETAIL_CHECKSUM NOT NULL VARCHAR2(32 CHAR)
PRICE NUMBER
IN_CONTRACT NOT NULL NUMBER
CREATED NOT NULL DATE
PROPERTY_WEB_ID NOT NULL VARCHAR2(100)
SOURCE_ID NOT NULL NUMBER
LISTING_CREATED NOT NULL DATE
ARCHIVE_NAME VARCHAR2(100)
DUPLICATES_GROUP_ID NUMBER
FILENAME VARCHAR2(80)
DISPLAY NUMBER
rfs.rfs_properties:
Name Null? Type
------------------------------- -------- -----------------
PROPERTY_ID NOT NULL NUMBER
LISTING_ID NOT NULL NUMBER
BLDG_PROPKEY NUMBER
UNIT_PROPKEY NUMBER
ADDRESSKEY NUMBER
HOUSE_NUMBER VARCHAR2(32)
STREET_ADDRESS VARCHAR2(200)
UNIT_NUMBER VARCHAR2(32)
UNIT_NUMBER_PARSED VARCHAR2(16 CHAR)
PARSED_ADDRESS VARCHAR2(255)
DISPLAY_ADDRESS VARCHAR2(150)
CROSS_STREET VARCHAR2(200)
NEIGHBORHOOD VARCHAR2(150)
NEIGHBORHOOD_CODE NUMBER
NEIGHBORHOOD_REG_CODE NUMBER
SCHOOL_DISTRICT VARCHAR2(100)
BOROUGH_CITY VARCHAR2(100 CHAR)
METRO_AREA VARCHAR2(100 CHAR)
ZIP_CODE NUMBER
COUNTY NUMBER
STATE VARCHAR2(4 CHAR)
ROOMS NUMBER
BEDROOMS NUMBER
BATHROOMS NUMBER
SQFT NUMBER
LOT_SIZE NUMBER
STUDIO NUMBER
LOFT NUMBER
MAINT_CC NUMBER
RE_TAX NUMBER
PROPERTY_TYPE_ID NUMBER
PROPERTY_TYPE VARCHAR2(255)
BLDG_NAME VARCHAR2(255)
BLDG_TYPE VARCHAR2(32 CHAR)
BLDG_NEW_DEVEL NUMBER
BLDG_FEATURES VARCHAR2(256)
MANUALLY_BLDG_FEAT VARCHAR2(255)
APT_FEATURES VARCHAR2(256)
OUTDOOR_SPACE VARCHAR2(32 CHAR)
YEAR_BUILT NUMBER
LISTING_RANK NOT NULL NUMBER
LOCATION_CHECKED NUMBER
PROPKEY_SOURCE VARCHAR2(15)
WEB_BUG_URL VARCHAR2(255)
EMAIL_LEAD_GENERATION VARCHAR2(100)
LISTING_URL VARCHAR2(255)
BROKER_NAME VARCHAR2(100)
BROKER_URL VARCHAR2(256)
LISTING_TEXT CLOB
IS_UPDATED NUMBER
CENTROID_X NUMBER(20,10)
CENTROID_Y NUMBER(20,10)
CENTROID MDSYS.SDO_GEOMETRY
COUNTY_GEO_ID NUMBER
CX NUMBER
CY NUMBER
oracle統計を更新した後に更新された統計：
統計学
31 recursive calls
2 db block gets
63053 consistent gets
15474 physical reads
0 redo size
2890 bytes sent via SQL*Net to client
524 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
10 rows processed
統計を更新した後の新しい実行プラン：
Execution Plan
----------------------------------------------------------
Plan hash value: 3213592672
--------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 10 | 4110 | 236 (0)| 00:00:03 |
|* 1 | COUNT STOPKEY | | | | | |
| 2 | NESTED LOOPS | | | | | |
| 3 | NESTED LOOPS | | 10 | 4110 | 236 (0)| 00:00:03 |
| 4 | TABLE ACCESS BY INDEX ROWID| RFS_LISTINGS | 224 | 4704 | 11 (0)| 00:00:01 |
|* 5 | INDEX RANGE SCAN | RFS_LISTINGS_DISPLAY | | | 3 (0)| 00:00:01 |
|* 6 | INDEX UNIQUE SCAN | RFS_PROPERTIES_LD730_UNIQUE | 1 | | 1 (0)| 00:00:01 |
|* 7 | TABLE ACCESS BY INDEX ROWID | RFS_PROPERTIES | 1 | 390 | 2 (0)| 00:00:01 |
--------------------------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter(ROWNUM<=10)
5 - access("LISTINGS"."DISPLAY"=1)
6 - access("LISTINGS"."LISTING_ID"="PROPERTIES"."LISTING_ID")
7 - filter(NLSSORT("PROPERTIES"."BOROUGH_CITY",'nls_sort=''BINARY_CI''')=HEXTORAW('6E657720796F726B
00') )