Databases Reference
In-Depth Information
[Finishes]
. If a temporal delete transaction's effective time
ends on the same clock tick as that of an episode, but begins
after that episode begins, it will withdraw all versions wholly or
partially included within its timespan. If one version is partially
within the timespan, the temporal delete will replace the part
of that withdrawn version not within its timespan. In either case,
the result is a {shorten forwards} transformation on that episode.
[Finishes
-1
]. If a temporal delete transaction's effective time
ends on the same clock tick as that of an episode, but begins
before that episode begins, it will {erase} the episode; and, in
addition, it will withdraw all other versions, for the same object,
that are wholly or partially included within its timespan.
Those other versions will exist within one or more earlier
episodes. On any of those episodes wholly included within the
transaction's timespan, there will be an {erase} transformation
on them, as well. The earliest episode within the transaction's
timespan may be wholly or partially included within that
timespan. If it is wholly contained, there will be an {erase} trans-
formation on it. Otherwise, there will be a {shorten backwards}
transformation. If the start of the transaction's timespan does
not fall on a version effective time boundary, then the temporal
delete will replace the part of that withdrawn version that is
not within its timespan.
[During]
. If a temporal delete transaction's effective time begins
after that of an episode, and ends before that episode ends, then
the transaction will withdraw all versions wholly or partially
included within its timespan. At most two versions can be par-
tially included in that timespan, those being the ones at the begin
and/or end of the timespan. This delete transaction carries out a
{split} transformation on the episode in question.
[During
-1
]. If a temporal delete transaction's effective time
begins before that of an episode, and ends after that episode ends,
then the transaction will {erase} the one or more episodes wholly
included within its timespan. In addition, as well as any number
of additional episodes wholly included within the transaction's
timespan, there may be one or two episodes only partially included
within the transaction's timespan. If there is an earlier but partially
included episode, the delete transaction will do a {shorten back-
wards} transformation on it. If there is a later but partially included
episode, the delete transaction will result in a {shorten forwards}
transformation. In either case, the partially included episode
may or may not have a partially included version; in other words,
the transaction's timespan may or may not align on version
boundaries. In either case, a partially included version is {split},
and the part outside the transaction's timespan is replaced.
