シャドーイング練習: what is a database index? - 動画で英語スピーキングを学ぶ
レッスンを作成中...
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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.
このビデオでスピーキングを練習する理由
このビデオでは、データベースのインデックスという概念について説明されています。英語での説明は専門的ですが、特定のテーマに沿った会話を持つことができるため、英語スピーキング練習に非常に適しています。このビデオを使って、リアルな文脈で英語を話すことができるため、学んだ内容を自分の言葉で再現する練習に最適です。実際のビジネスやテクノロジーに関連したトピックを扱うことで、より実践的な表現力が身につき、英語のスキル向上につながるでしょう。YouTubeで英語学習をしながら、効果的に英語を話す力をつけましょう。
文脈における文法と表現
- 短縮形の使用 - スピーカーは「we've」や「it's」などの短縮形を使用して、より自然な会話のリズムを保っています。このような表現をマスターすることで、流暢さを向上させることができます。
- 疑問文の構造 - スピーカーが情報を引き出すために使う疑問文は、質問の仕方を学ぶのに役立ちます。「How do you find something in this pile of stuff?」のような配置を真似することで、質問力が向上します。
- 比較表現 - 「the best solution to search billions of rows is to avoid searching billions of rows」というように、比較かつ反復する表現方法は、説得力を持たせるために有効です。
一般的な発音の罠
スピーカーの発音で注意が必要な部分はいくつかあります。特に「index」や「documents」といった単語は、発音が似ていますが、微細な声のトーンや強調が異なります。これらの単語を正確に発音するためには、音声を何度も聞き、繰り返し練習することが効果的です。また、速いスピードでの会話に慣れるためにも、shadow speechの練習を行うことが推奨されます。自分の発音とスピーカーの発音を合わせて繰り返すことで、より自然な英語が話せるようになります。
シャドーイングとは？英語上達に効果的な理由
シャドーイング（Shadowing）は、もともとプロの通訳者養成プログラムで開発された言語学習法で、多言語習得者として知られるDr. Alexander Arguelles によって広く普及されました。方法はシンプルですが非常に効果的：ネイティブスピーカーの英語を聞きながら、1〜2秒の遅延で声に出してすぐに繰り返す——まるで「影（shadow）」のように話者を追いかけます。文法ドリルや受動的なリスニングと異なり、シャドーイングは脳と口の筋肉が同時にリアルタイムで英語を処理・再現することを強制します。研究により、発音精度、抑揚、リズム、連音、リスニング力、そして会話の流暢さが大幅に向上することが確認されています。IELTSスピーキング対策や自然な英語コミュニケーションを目指す方に特におすすめです。