Puas yog cov yuam sij tseem ceeb indexed?
Puas yog cov yuam sij tseem ceeb indexed?

Video: Puas yog cov yuam sij tseem ceeb indexed?

Video: Puas yog cov yuam sij tseem ceeb indexed?
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Yog a thawj tus yuam sij yog ib txwm ib qhov ntsuas . Yog tias koj tsis muaj lwm pawg qhov ntsuas ntawm lub rooj, ces nws yog ib qho yooj yim: ib pawg qhov ntsuas ua kom lub rooj nrawm dua, rau txhua qhov haujlwm. Yog tias koj tsis muaj ib qho, nws pom tseeb heev DTA yuav pom zoo ib qho, thiab muab tso rau hauv Lub Ntsiab Tseem Ceeb kem(s) los ntawm lub neej ntawd.

Ib yam li ntawd, nws tau nug, yog cov yuam sij tseem ceeb indexed los ntawm lub neej ntawd?

Yog, nws tsim ib pawg qhov ntsuas ntawm thawj tus yuam sij los ntawm ua ntej . Yuav kom ncaj, SQL tsim ib qho qhov ntsuas ntawm TSEEM CEEB (PK) lo lus tseem ceeb. Qhov ntawd qhov ntsuas yog ib qho txawv, Clustered Index . Koj tsuas tuaj yeem muaj ib qho "CLUSTERED" qhov ntsuas.

Tom qab ntawd, lo lus nug yog, qhov sib txawv ntawm qhov tseem ceeb thiab qhov ntsuas qhov tseem ceeb yog dab tsi? Lub Ntsiab Tseem Ceeb : uas yog siv rau tshwj xeeb txheeb xyuas kab perticular ntawm lub rooj database. Thawj INDEX : Uas yog siv rau tau ib qhov ntsuas los ntawm lub rooj database thiab qhov ntawd indexing yog ua los ntawm tshwj xeeb raws li.

Ntawm no, yog cov yuam sij tseem ceeb indexed Postgres?

PostgreSQL cia li tsim ib qho qhov ntsuas rau txhua qhov kev txwv tshwj xeeb thiab thawj tus yuam sij kev txwv los tswj kev tsis sib haum xeeb. Yog li, nws tsis tsim nyog los tsim ib qho qhov ntsuas qhia meej rau thawj tus yuam sij kab.

Puas yog cov yuam sij txawv teb chaws indexed?

3 Teb. SQL Server yuav tsis cia li tsim ib qho qhov ntsuas ntawm a txawv teb chaws tus yuam sij. A FOREIGN KEY constraint tsis tas yuav txuas mus rau PRIMARY nkaus xwb KEY txwv nyob rau hauv lwm lub rooj; Nws kuj tseem tuaj yeem txhais tau los siv cov kab ntawm UNIQUE txwv hauv lwm lub rooj.

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