Video: Hom ntaub ntawv yog dab tsi?
2024 Tus sau: Lynn Donovan | [email protected]. Kawg hloov kho: 2023-12-15 23:47
Tuav cov chaw nyob uas xa mus khoom . Koj tuaj yeem muab txhua qhov kev siv hom (txoj hlua, array, chav kawm, orinterface) rau ib Cov khoom sib txawv . Ib Cov khoom sib txawv tuaj yeem xa mus rau cov ntaub ntawv ntawm tej yam muaj nqis hom (tus lej, Boolean, Char, Hnub tim, qauv, lossis kev suav).
Ib yam li ntawd, Dtype object yog dab tsi?
luam tawm (" dtype ua yog: ", a. dtype ua ) chevron_right. Cov zis: hom yog: dtype ua yog:32. Cov ntaub ntawv hom Khoom nrog Structured Arrays: Cov ntaub ntawv hom ntawv muaj txiaj ntsig zoo rau kev tsim cov qauv arrays. Ib tug structuredarray yog ib qho uas muaj ntau hom ntaub ntawv.
Kuj Paub, dab tsi yog hom ntaub ntawv hauv Java? Nws yog ib tug template los yog blueprint los ntawm qhov tshwj xeeb khoom yog tsim. Ib khoom yog ib qho piv txwv tshwj xeeb ntawm chav kawm nrog nws tus kheej lub xeev. A Java Cov ntawv tshaj tawm hauv chav kawm piav txog cov ntsiab lus tseem ceeb ntawm ib qho twg khoom ntawm chav kawm: Cov ntaub ntawv cov tswv cuab: Cov hloov pauv uas sawv cev rau lub xeev ntawmthe khoom.
Cov lus nug tseem yog, cov ntaub ntawv piv txwv yog dab tsi?
Ib khoom hom yog lub hauv paus tswvyim lossis lub tswv yim ntawm ib qho khoom ; rau piv txwv , lub tswvyim ntawm lub rooj los yog index. An khoom instance yog ib piv txwv ntawm ib khoom hom. Rau piv txwv , lub rooj hu ua CUSTOMER_MASTER yog ib qho piv txwv ntawm khoom hom TAB.
Cov khoom puas yog hom ntaub ntawv universal?
VARIANT yog ib hom universal uas tuaj yeem siv los khaws yuav luag txhua yam cov ntaub ntawv : tooj, hlua, hnub tim/lub sij hawm, tseeb/false, references to khoom , arrays thiab sai sai.
Pom zoo:
Cov ntaub ntawv hom thiab cov qauv ntaub ntawv yog dab tsi?
Cov qauv ntaub ntawv yog ib txoj hauv kev piav qhia txog ib txoj hauv kev los npaj cov ntaub ntawv kom ua haujlwm andalogrithms tuaj yeem siv tau yooj yim dua. Ib hom ntaub ntawv piav qhia txog cov ntaub ntawv uas txhua tus sib koom ua ke. Piv txwv li tus lej cov ntaub ntawv hom piav qhia txhua tus lej uas lub khoos phis tawj tuaj yeem ua tau
Dab tsi yog hom ntaub ntawv thiab cov ntaub ntawv sib txawv?
Qee cov ntaub ntawv muaj xws li cov lej, cov lej ntab, cov cim, cov hlua, thiab cov arrays. Lawv kuj tseem yuav yog hom tshwj xeeb, xws li hnub tim, timestamps, booleanvalues, thiab varchar (tus cwj pwm sib txawv) cov qauv
Dab tsi yog lub hom phiaj ntawm delimiters nyob rau hauv cov ntawv sau npe ob hom ntawv cov ntaub ntawv delimiters?
Cov ntaub ntawv delimited yog cov ntawv nyeem siv los khaws cov ntaub ntawv, uas txhua kab sawv cev rau ib phau ntawv, tuam txhab, lossis lwm yam, thiab txhua kab muaj cov teb sib cais los ntawm tus lej
Dab tsi yog hom ntaub ntawv thiab piav qhia nws hom?
Hom ntaub ntawv. Ib hom ntaub ntawv yog hom ntaub ntawv. Qee cov ntaub ntawv muaj xws li cov lej, cov lej ntab, cov cim, cov hlua, thiab cov arrays. Tej zaum lawv kuj yuav yog hom tshwj xeeb, xws li hnub tim, timestamps, boolean qhov tseem ceeb, thiab varchar (tus cwj pwm txawv)
Hom ntaub ntawv twg ntawm Hadoop tso cai rau columnar cov ntaub ntawv cia hom?
Columnar ntaub ntawv tawm tswv yim (Parquet, RFile) Qhov tseeb hotness nyob rau hauv cov ntaub ntawv tawm tswv yim rau Hadoop iscolumnar cov ntaub ntawv cia. Yeej qhov no txhais tau hais tias tsis yog cia li khaws cov kab ntawm cov ntaub ntawv nyob ib sab rau ib leeg koj kuj khaws cov kab ntawv nyob ib sab. Yog li datasets tau muab faib ua ob qho tib si horizontally thiab vertically