Cov txheej txheem:

Dab tsi yog cov kauj ruam yooj yim ntawm kev nug optimizer?
Dab tsi yog cov kauj ruam yooj yim ntawm kev nug optimizer?

Video: Dab tsi yog cov kauj ruam yooj yim ntawm kev nug optimizer?

Video: Dab tsi yog cov kauj ruam yooj yim ntawm kev nug optimizer?
Video: Koj Hais Dab Tsi?/Suabci Kwm & Ab Meej Ham/Official MV 2023 2024, Hlis ntuj nqeg
Anonim

Cov kauj ruam rau Query Optimization

Lus nug optimization koom nrog peb cov kauj ruam , yog nug tsob ntoo tiam, npaj tiam, thiab nug phiaj xwm txheej txheej. A nug tsob ntoo yog tsob ntoo cov ntaub ntawv qauv sawv cev rau kev sib raug zoo algebra qhia. Cov rooj ntawm cov nug yog sawv cev raws li nplooj nodes

Tib neeg kuj nug, dab tsi yog cov lus nug optimization txheej txheem?

Lus nug optimization yog ib feem ntawm kev nug nyob rau hauv uas lub database system sib piv sib txawv nug cov tswv yim thiab xaiv ib qho nrog tus nqi tsawg kawg nkaus. Lub optimizer kwv yees tus nqi ntawm txhua tus ua txoj kev ntawm nug thiab xaiv qhov uas muaj qhov kwv yees qis tshaj plaws. Tam sim no, feem ntau cov tshuab siv qhov no.

Ib tug kuj yuav nug, dab tsi yog lub ntsiab heuristic rau optimizing lus nug? Ib tug ntawm lub ntsiab heuristic cov kev cai yog siv SELECT thiab PROJECT cov haujlwm ua ntej thov JOIN lossis lwm yam haujlwm binary, vim tias qhov loj ntawm cov ntaub ntawv uas tshwm sim los ntawm kev ua haujlwm binary-xws li JOIN-feem ntau yog qhov ua haujlwm ntau ntawm qhov ntau thiab tsawg ntawm cov ntaub ntawv nkag.

Ntxiv rau qhov no, cov lus nug ua cov hauv paus ntsiab lus thiab kev ua kom zoo yog dab tsi?

Cov lus nug ua thiab kev ua kom zoo (hloov tshiab) The nug optimization Cov txheej txheem yog siv los xaiv txoj kev npaj ua kom tau zoo uas yuav txo qis lub sijhawm ua haujlwm nrog rau ntau yam kev pabcuam xws li tus lej disk I / O, CPU sijhawm thiab lwm yam.

Cov lus nug optimization nrog piv txwv yog dab tsi?

Lus nug optimization yog ib tug feature ntawm ntau relational database tswj systems. Cov nug optimizer sim txiav txim siab txoj kev ua tau zoo tshaj plaws los ua kom tiav qhov muab nug los ntawm kev xav txog qhov ua tau nug kev npaj.

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