• Share
  • Email
  • Embed
  • Like
  • Save
  • Private Content
Dw design fact_tables_types_6
 

Dw design fact_tables_types_6

on

  • 474 views

Tipos de tablas de hechos

Tipos de tablas de hechos

Statistics

Views

Total Views
474
Views on SlideShare
474
Embed Views
0

Actions

Likes
0
Downloads
9
Comments
0

0 Embeds 0

No embeds

Accessibility

Categories

Upload Details

Uploaded via as Adobe PDF

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

    Dw design fact_tables_types_6 Dw design fact_tables_types_6 Presentation Transcript

    • DATA WAREHOUSINGMulti DimensionalData Modeling.Fact Table Types
    • 2
    •  Transaction  Track processes at discrete points in time when they occur  Periodic snapshot  is a fact table that records activity during a repeating predictable time period, like the monthly summary of a bank account  Accumulating snapshot  A snapshot of the most recent state of something and therefore the dimensional foreign keys and the facts are, in general, over-written as time progresses3
    •  Transaction-grained fact tables are often richly dimensional and usually have only a single fact (the amount of the transaction).4
    •  Periodic snapshot records are generally repeated each reporting period as long as the thing being measured (like the account) is in existence.5
    •  Periodic snapshots are appropriate for long running processes that extend over many reporting periods.6
    •  Accumulating snapshots, are used for short processes that have a definite beginning and end, such as an order being filled.7
    •  For an order, we would usually make a record for each line on the order, and we would revisit the record making updates as the order progressed through the pipeline8
    •  The simplest implementation of an accumulating snapshot does not give you intermediate points in the history of, for example, an order.9
    •  Accumulating snapshots typically have multiple dates in the fact table representing the major milestones of the process. However, just because a fact table has several dates doesn’t dictate that it is an accumulating snapshot.  The primary differentiator of an accumulating snapshot is that we typically revisit the fact rows as activity takes place.10
    •  The Data Warehouse Toolkit.Second Edition.The Complete Guide to Dimensional Modeling.Ralph Kimball.Margy Ross