Sybase 12.5.1, User Manual

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Designing playback views
162
Historical Server
Designing playback views
This section describes the following topics:
• Rules for specifying input sessions
• Relationship of input views to playback views
• Rules for defining raw playback views
• Rules for defining non-raw playback views
Rules for specifying input sessions
When you are using multiple input sessions to create a playback session to a
file, no time gaps are allowed in input sessions. That is, when target is
file
, no
gaps can exist between an input session’s end time and the next input session’s
start time.
For example, if you collected data from 9 a.m. to 5 p.m. every day from
Monday through Friday, you could not play back those five recording sessions
to create a new, summarized, weekly session. However, if you eliminate the
time gaps by collecting data from 9 a.m. to 9 a.m. every day from Monday
through Friday, you could use the playback feature to create a new, summarized
weekly session. Another way to eliminate the time gaps is to keep the 9 a.m. to
5 p.m. recording session, but add another set of recording sessions scheduled
from 5 p.m. to 9 a.m. Use a longer sample interval for the off hours to reduce
the volume of data collected.
Relationship of input views to playback views
Use the
hs_create_playback_session
command to create a playback session.
Then use one or more
hs_create_playback_view
commands to add views to the
playback session. A playback session must contain at least one view. It can
contain more than one view.
In the
hs_create_playback_session
command, you specify the input session IDs
that you want to include in the playback. The input views are the views that
were defined for the input recording sessions. A playback view defines which
data items in the corresponding input view you want to play back.