Puas indexes qeeb hloov tshiab?
Puas indexes qeeb hloov tshiab?

Video: Puas indexes qeeb hloov tshiab?

Video: Puas indexes qeeb hloov tshiab?
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Anonim

1 Teb. Database indexes ua database hloov tshiab qeeb thiab sai dua tib lub sijhawm. Qhov no nyob ntawm tus hloov tshiab nqe lus: Thaum koj muaj hloov tshiab ntawm txhua kab zoo li hloov tshiab mytable set mycolumn = 4711 ces qhov ntsuas creation yuav qeeb tus hloov tshiab , vim nws yog ib co haujlwm ntxiv uas xav tau sijhawm.

Raws li, ua indexes ceev hloov tshiab?

Index muaj nuj nqis rau inserts, tshiab , thiab deletes. Derby yuav tsum ua ua hauj lwm tswj indexes . Yog koj hloov tshiab ib lub rooj, lub system yuav tsum tswj cov indexes uas yog nyob rau kab kho tshiab . Yog li muaj ntau indexes ua tau ceev ceev xaiv cov nqe lus, tab sis maj mam ntxig ntxig, tshiab , thiab deletes.

Yuav ua li cas indexes cuam tshuam qhov hloov tshiab thiab tshem tawm kev ua haujlwm? Ib txoj cai ntawm tus ntiv tes xoo yog qhov ntau indexes koj muaj nyob rau ntawm lub rooj, qhov qeeb INSERT , UPDATE, thiab DELETE kev ua haujlwm yuav yog. Qhov no yog vim li cas ntxiv indexes rau kev ua tau zoo yog kev lag luam tawm, thiab yuav tsum sib npaug kom zoo. Yog, nws kiag li cuam tshuam kev ua haujlwm rau INSERTUPDATEDELETE kev ua haujlwm.

Ib yam li ntawd ib tug yuav nug, puas indexes slow down inserts?

1 Teb. Index thiab kev txwv yuav qeeb inserts vim tias tus nqi kuaj xyuas thiab tswj cov no tsis pub dawb. Cov nyiaj siv ua haujlwm tsuas tuaj yeem txiav txim siab nrog kev ntsuas kev ua tau zoo.

Yuav ua li cas indexes cuam tshuam rau database kev ua tau zoo?

Index yog cov qauv ntaub ntawv uas tso cai rau koj xaiv sai thiab txheeb cov kab hauv a database rooj. Piv txwv li, yog tias koj cov ntxhuav feem ntau cuam tshuam los ntawm INSERT, Hloov Kho, lossis DELETE cov lus, ces koj tag nrho kev ua tau zoo poob vim indexes yuav tsum tau hloov kho tom qab cov haujlwm ntawd.

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