Transcript transparencies

TAG DataBase
What it is ?
Why we need it ?
Size, content, access…
24 Feb 2004
TAG DataBase K.Safarik
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Event Model

RAW Data; written once, read (not too) many times
 size: 1 – 50 MB per event, exist only one per event

ESD; written (not too) many times, read many times
 size: ~ 1/10 of raw per event, exist only one per event

AOD; written many times, read many times
 size: ~ 1/10 of ESD per event, exist many (~10) per event
…
 TAG; written (not too) many times, read many times
 size: 100 B – 1 kB per event, exist many per event
 this is done for fast event data selection
 it’s not directly for analysis, histogram production etc.
 even (by chance) if the information is there you may do it
 for discussion
 global experiment TAGs
 physics working group TAGs
 user defined TAGs
24/2/2005 TAG DataBase K.Safarik
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TAG structure

Event building information
 allows to find all the information about the event
 event ESD and all the AODs
 maybe also RAW Data (hopefully will not be used often)
 … (this is not my job)

Physics information
 query-able (that’s on what you select data)
 information about trigger, quality etc.
 usually same global physics variable
 but also one may have there which may not too much
physical sense but is good for selection
24/2/2005 TAG DataBase K.Safarik
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TAG size

Has to be reasonable to be able to query in reasonable
time
 somewhere around disk size --- O(100GB)

Typical yearly number of events
 107 for heavy ion
 109 for pp

However
 TAG size (in principle) is independent on multiplicity
 but it is collision-system dependent, trigger dependent…
 for heavy-ion: few kB gives few 10 GB
 for pp: 100 B gives 100 GB
 STAR: 500 physics tag fields in 0.5 kB (in average 1 par B)
24/2/2005 TAG DataBase K.Safarik
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TAG content
(only physics information)
 technical part – the same for every TAG database
 run number, event number, bunch crossing number, time
stamp
 trigger flags (an event may be trigger by more than one
trigger class), information from trigger detectors
 quality information: which detectors were actually on,
what was their configuration, quality of reconstruction
 physics part – partly standard, partly trigger/physics/user
dependent
 charged particle multiplicity
 maximum pt
 sum of the pt
 maximum el-mag energy
 sum of el-mag energy
 number of kaons
…
24/2/2005 TAG DataBase K.Safarik
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
TAG construction
Basic (experiment wide) TAG database
 written during reconstruction – ESD production
 but it has also to navigate to (all ?) AOD (produced later) ?
 there is part which is untouchable (nobody is allowed to
modify)
 there is part which maybe modified, as result of further
analysis

From this one all other TAG databases start
 the real content of definite instant of TAG database
 trigger dependent
 detector configuration dependent
 physics analysis dependent
 define the physics group TAG databases
 derived from experiment wide database
 maybe allow for user TAG databases
 derived from physics group database

Useful tag fields are then pushed up in this hierarchy
24/2/2005 TAG DataBase K.Safarik
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TAG conclusion
 we have to define prototype of experiment-wide TAG
database
 implement this in reconstruction program
 physics working group – to define physic group
databases
 test the mechanism of inheritance from experiment-wide TAG
database
 decide if the ‘event building’ information has to allow to
navigate
to all the AODs
or just to those created within that working group
 when ?, who ?
24/2/2005 TAG DataBase K.Safarik
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