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TAG DataBase

TAG DataBase. What it is ? Why we need it ? Size, content, access…. 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

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TAG DataBase

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  1. TAG DataBase What it is ? Why we need it ? Size, content, access… TAG DataBase K.Safarik

  2. 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

  3. 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

  4. 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)

  5. 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 • …

  6. 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

  7. 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 ?

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