Summary
samenvatting theorie Relational Databases & Datawarehousing
- Course
- Institution
samenvatting theorie Relational Databases & Datawarehousing
[Show more]
Seller
Follow
easyIT
Reviews received
Content preview
1Samenvatting RDDW (theorie)
Hoofstuk 5: indexen...............................................................................................................................3
Hoofdstuk 6: Basics of Transaction Management................................................................................12
Hoofdstuk 7: Datawarehousing + BI (zie ook oefeningen!)..................................................................22
Hoofdstuk 8: NoSQL – Not only SQL.....................................................................................................31
,2
, 3
Hoofstuk 5: indexen
Intro
Wat?
o Een geordende structuur v/d tabel
o B-tree = balanced tree
Waarom?
o Veel snellere query uitvoering
o Kan unieke rijen forceren
Waarom niet?
o Veel storage (overhead)
o Kan updates, deletes en inserts vertragen, omdat indexen ook veranderd moeten worden
Table Scan
Normaal is de db een heap: data wordt gewoon toegevoegd waar er plaats is
Table scan: een query moet dus heel de tabel overlopen om alle waarden te vinden.
Table Seek
Zoekt naar de index key value ig in de boomstructuur (dus niet heel de tabel moet overlopen
worden, cuz ge navigeert in de boom)
, 4
Clustered index
Is de tabel, waarbij een paar index pagina’s gemaakt zijn zodat queries hier zo kunnen door
navigeren. het wordt een boomstructuur.
o Clustered: direct op de data
o Er kan dus maar 1 clustered index zijn per tabel
Bv telefoonboek: geordend op naam en bovenaan de pagina zieje dan van welke en tot welke
naam er op die pagina staat.
Voorbeeld
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller easyIT. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $5.35. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
55628 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now