Video: Dab tsi yog sparse kab hauv SQL Server 2008?
2024 Tus sau: Lynn Donovan | [email protected]. Kawg hloov kho: 2023-12-15 23:47
Sparse Columns hauv SQL Server : Kev cuam tshuam rau Lub Sijhawm & Chaw. SQL Server 2008 qhia sparse kab raws li ib txoj hauv kev los txo qhov cia rau qhov tsis muaj nuj nqis thiab muab ntau qhov kev nthuav dav ntxiv. Kev lag luam tawm yog tias muaj nyiaj siv ua haujlwm ntxiv thaum koj khaws thiab khaws cov txiaj ntsig tsis yog NULL.
Nyob rau hauv txoj kev no, dab tsi yog kem sparse hauv SQL Server?
A SPARSE kab yog hom dog dig kem uas tau optimized cia rau NULL qhov tseem ceeb. Hauv lwm lo lus, a SPARSE kab zoo dua ntawm kev tswj NULL thiab ZERO qhov tseem ceeb hauv SQL Server . Nws tsis nyob ib qho chaw hauv lub database. Siv a SPARSE kab peb yuav txuag tau li 20 mus rau 40 feem pua ntawm qhov chaw.
Kuj Paub, dab tsi yog kab teeb hauv SQL Server? Cov txheej txheem rau xaiv cov ntaub ntawv los ntawm kab ke
- Conceptually, ib kem teeb yog ib hom ntawm updataable, xam XML kem uas aggregates ib pawg ntawm cov kab hauv qab kev sib raug zoo rau hauv ib qho XML sawv cev.
- Hauv SQL Server Management Studio cov lus editor, kab teeb tsa tau tshwm sim raws li qhov kho tau XML teb.
Ib yam li ntawd, koj tuaj yeem nug, hom ntaub ntawv twg tuaj yeem teev nrog sparse?
A SPARSE kab yuav tsum yog nullable thiab tsis tuaj yeem muaj ROWGUIDCOL lossis IDENTITY cov khoom. A SPARSE kab ua tsis tau hom ntaub ntawv xws li ntawv, ntext, duab, timestamp, user-defined hom ntaub ntawv , geometry, lossis geography. Nws tsis tuaj yeem muaj tus nqi tsim nyog thiab ua raws li txoj cai.
Dab tsi yog ib qho ntawm cov cwj pwm hauv qab no yuav tsum tau siv los ua kom zoo rau kev khaws cia rau qhov tsis muaj nuj nqis?
Sparse kab muaj cov raws li yam ntxwv: SQL Server Database Cav siv SPARSE lo lus tseem ceeb hauv kab lus txhais rau ua kom zoo tus khaws cia ntawm tus nqi hauv kem ntawd. Yog li ntawd, thaum kab tus nqi yog NULL rau txhua kab hauv lub rooj, lub tus nqi xav tsis muaj khaws cia.
Pom zoo:
Koj qhia li cas yog kab laum yog kab kab?
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Dab tsi yog sparse kem Dab tsi yog qhov zoo thiab qhov tsis zoo?
Koj poob 4 bytes tsis yog ib zaug ib kab; tab sis rau txhua lub cell hauv kab uas tsis yog null. Qhov zoo ntawm SPARSE kem yog: Qhov tsis zoo ntawm SPARSE kem yog: SPARSE kem tsis tuaj yeem siv rau ntawm cov ntawv, ntext, duab, timestamp, geometry, geography lossis cov neeg siv cov ntaub ntawv teev tseg
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