Databases Reference
In-Depth Information
Comments:
The effective end date of an episode is the effective end date of its latest
version.
Components:
9999, effective end date, episode.
open version
Mechanics:
a version whose effective end date is 9999.
Semantics:
a version whose effective end date is unknown.
Components:
9999, effective end date, version.
open-closed
Mechanics:
a convention for using a pair of clock ticks to designate an effective or
assertion time period, in which the earlier clock tick is the last clock tick
before the first clock tick in the time period, and in which the later clock tick
is the last clock tick in the time period.
Comments:
Using this convention, two time periods [meet] if and only if the begin
date of the later one is the same clock tick as the end date of the
earlier one, at whatever level of granularity is used to designate the clock
ticks.
Components:
assertion time period, clock tick, effective time period.
open-open
Mechanics:
a convention for using a pair of clock ticks to designate an effective or
assertion time period, in which the earlier clock tick is the last clock tick before
the first clock tick in the time period, and in which the later clock tick is the first
clock tick after the last clock tick in the time period.
Comments:
Using this convention, two time periods [meet] if and only if the begin
date of the later one is one clock tick before the end date of the
earlier one, at whatever level of granularity is used to designate the clock
ticks.
Components:
assertion time period, clock tick, effective time period.
outflow pipeline dataset
Mechanics:
a dataset whose origin is one or more production tables.
Comments:
Outflow pipeline datasets are tabular data which has been a part of the
production database; they are the persisted result sets of SQL queries
or equivalent processes. They are either end state result sets, i.e.
immediately delivered to internal business users or exported to outside
users, or are augmented as they move along an “outflow data pipeline”
leading to a final state in which they are delivered to internal business
users or outside users.
The termination points of outflow pipelines may be either internal to the
organization, or external to it; and we may think of the data that flows
along these pipelines to be the result sets of queries applied to those
production tables. (From Chapter 12.)
Components:
dataset, production table.
override
Mechanics:
to set the assertion end date of a row to the same value as its assertion
begin date.
