Shadowing Practice: what is a database index? - Learn English Speaking with Video
Les maken...
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we really need to talk about what do we mean by
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an index very quick we added this concept of indexes
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because of a problem
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that we have in database systems you see we have regardless
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of the way you store your data whether it's a relational table of columns and rows or documents or blob storage
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this data is huge in your table you're going to have millions
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and millions of rows in your documents you're going to have thousands
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and thousands of documents in your blob stores you're going to
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have these content these blob pictures videos whatever contiguous one of the other
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but searching becomes interesting
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because how do you find something in this pile of stuff you get a scan one by one
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these million rows or thousands of document or tens
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and thousands of these blob images which is obviously not ideal
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because you have to loop one by one
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and you have to visit apparently work with millions of rows to find what you're looking for
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so so smart people found a way to eliminate working with millions of millions of rows
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and instead work with as few
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or rows as possible to find exactly what we're looking for
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the the best solution to search billions of rows is to
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avoid searching billions of rows right that's that's the best solution
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so the trick here is to take shortcuts so indexes was well born
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and there are many many types of indexes
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that helps you you know find exactly what you're looking for
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or at least narrow the search not exactly gives you one io or one cost bigger of one not necessarily
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but it helps you you know narrow
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that search that's the goal of an index
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so regardless of the type of it is a b3 b
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plus tree you know uh jest tree generalized search tree
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or brand the goal is just let me work with as let me eliminate things
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that is absolutely doesn't contain my results right just like concept of a bloom filter
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so that's an index so i have an index
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and you search this index so you still need to search
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but it's a much much much smaller data structure compared to the millions of rows
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that you have on your actual data blob store documents right
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usually you keep we call this area the heap right the heap is a data structure where you just dump everything
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ram it's just a dumping ground index is an optimized data structure
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that helps you pick what column in your document
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or on your row on your table and exactly index
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that column and the goal is to give you give you a row sets right a sets of rows
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that are candidate
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that may give you the results after you search the index
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you get a list of candidate results right could be one
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or could be more you still in most situations you still
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need to go to jump to the heap to the big table
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which contains actual data and fetch the content
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because the index will only have one column
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or two right the heap will have everything in it
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so you jump back but the index tells you exactly where to jump
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and that is the trick here the index tells you hey jump to page 179
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and pull row 73 in that page it tells you exactly
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that right now it depends on the database the database is
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sometimes does an additional filtering upon fetching the row itself
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because there are situations where the row might have been deleted
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but the index wasn't updated and and we need to see
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if i'm supposed to see this row or not
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so whether whether you're in a multi-version currency control or not so this is an index Cool.
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Sounds like a good data structure, right?
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Beautiful.
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Let's always add an index.
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Why not?
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But careful with that.
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What did we say?
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We said that the index gives you a candidate rows so
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that you go to the table and fetch exactly what you want.
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Right?
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Cool.
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Keep that in mind.
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Okay.
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Woordenschat en spreektips bij deze les
Deze video bevat 68 zinnen en 696 woorden om na te spreken. Het gesproken deel duurt 5:12. De spreker praat in een gelijkmatig tempo van ongeveer 134 woorden per minuut, prettig om te shadowen. 87% van de woorden hoort bij de 3.000 meest gebruikte Engelse woorden, dus de woordenschat is goed te volgen.
Belangrijke woorden in deze video
15 minder gangbare woorden uit de video, met uitspraak en betekenis:
- column /ˈkɒləm/ (zelfstandig naamwoord) — zuil, kolom. A solid upright structure designed usually to support a larger structure above it, such as a roof or horizontal beam, but sometimes for decoration.
- database /ˈdeɪtəˌbeɪs/ (zelfstandig naamwoord) — database, databank. A collection of (usually) organized information in a regular structure, usually but not necessarily in a machine-readable format accessible by a computer.
- fetch /fɛt͡ʃ/ (werkwoord) — halen. To retrieve; to bear towards; to go and get.
- regardless /ɹɪˈɡɑɹd.lɪs/ (bijwoord) — desondanks, niettemin. Without attention to warnings or indications of bad consequences.
- narrow /ˈnæɹəʊ/ (bijvoeglijk naamwoord) — nauw, smal. Having a small width; not wide; having opposite edges or sides that are close, especially by comparison to length or depth.
- filter /ˈfɪltɚ/ (zelfstandig naamwoord) — filter. A device which separates a suspended, dissolved, or particulate matter from a fluid, solution, or other substance; any device that separates one substance from…
- eliminate /ɪˈlɪm.ɪ.neɪt/ (werkwoord) — elimineren. To completely remove, get rid of, put an end to.
- dump /dʌmp/ (werkwoord) — dumpen. To release, especially in large quantities and chaotic manner.
- necessarily /ˌnɛs.əˈsɛɹ.ə.li/ (bijwoord) — nodig, noodzakelijk. Inevitably; of necessity.
- compare /kəmˈpɛɚ/ (werkwoord) — vergelijken. To assess the similarities and differences between two or more things [“to compare X with Y”]. Having made the comparison of X with Y, one might have found it…
- ideal /aɪˈdi(ə)l/ (bijvoeglijk naamwoord) — ideaal, optimaal. Pertaining to ideas, or to a given idea.
- currency /ˈkʌɹ.ən.si/ (zelfstandig naamwoord) — munteenheid, valuta. Money or other items used to facilitate transactions.
- loop /luːp/ (zelfstandig naamwoord) — lus, strop. A length of thread, line or rope that is doubled over to make an opening.
- delete /dɪˈliːt/ (werkwoord) — verwijderen. To remove, get rid of or erase, especially written or printed material, or data on a computer or other device.
- depend /dɪˈpɛnd/ (werkwoord) — afhangen. To be contingent or conditioned; to have something as a necessary condition
Phrasal verbs die je zult horen
- look for (werkwoord) — zoeken. To seek.
Uitspraak om op te letten
De spreker gebruikt 10 samentrekkingen en verkorte vormen, zoals you're, doesn't, I'm. Spreek ze kort uit, zoals je ze hoort.
- Lange woorden — let op de klemtoon: eliminate /ɪˈlɪm.ɪ.neɪt/, necessarily /ˌnɛs.əˈsɛɹ.ə.li/, contiguous /kənˈtɪɡ.ju.əs/, generalize /ˈd͡ʒɛn.(ə.)ɹə.laɪz/
Zo oefen je met deze video
- Luister de hele video één keer zonder te spreken en noteer de woorden die je niet kent.
- Spreek zin voor zin na op normale snelheid en herhaal elke zin tot je ritme gelijk is aan dat van de spreker.
- Neem jezelf op en vergelijk met het origineel; let daarbij op woorden als column, database, fetch.
Wat is de Shadowing-techniek?
Shadowing is een wetenschappelijk onderbouwde taalleermethode die oorspronkelijk is ontwikkeld voor professionele tolkentraining en gepopulariseerd door polyglot Dr. Alexander Arguelles. De methode is eenvoudig maar krachtig: je luistert naar native Engelse audio en herhaalt het onmiddellijk hardop — als een schaduw die de spreker volgt met slechts 1–2 seconden vertraging. In tegenstelling tot passief luisteren of grammaticadrills, dwingt shadowing je hersenen en mondspieren om echte spraakpatronen tegelijkertijd te verwerken en te reproduceren. Onderzoek toont aan dat het de uitspraaknauwkeurigheid, intonatie, ritme, verbonden spraak, luisterbegrip en spreekvaardigheid aanzienlijk verbetert — waardoor het een van de meest effectieve methoden is voor IELTS Speaking-voorbereiding en echte Engelse communicatie.