Star%20Database%20Tutorial

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Star Database Tutorial

• Package Design Objectivity Discussion
• Interface Questions
• What do you want? -gt making requests
• What do you get? -gt data container
• How to add a new object type? -gt definition
  protocols
• How do you update? -gt db input protocols

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Objectivity OODB w/ C API

• Is a Database
• Persistency Mechanism
• Concurrency Locking Mechanisms
• Access by Query on predefined fields
• Fast search over large data samples

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Objectivity OODB w/ C API

• Is an OO Database
• Provides Direct Navigation tools to data
• Gives OO methodology to persistent data
• But
• Direct Navigation was attractive for Event-Store
• Persistent-to-Transient copy allows adding OO
  methodology at copy level

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Conditions DB Description

• Database of the experimental conditions.
• Database Access
• Updates are predominantly done from Online
• Storage retrieval by timestamp
• Update Frequency
• pre-determined updates (e.g. hourly snap-shot)
• alarm-activated updates (at level of individual
  object)
• Data Volume
• moderate per update (Mbyte)
• moderately large in aggregate (gtGbytes)

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Star-BaBar Conditions DB

• Is applied to each Subsystem (e.g. tpc, svt, ..)
• conditions/subsystem/UniqueObjects
• conditions/subsystem/Index-to-Objects
• e.g.
• TPCVoltages Sector_01Voltages represent
• unique ( uniquely named) object types stored
• in the conditions/tpc/databases
• accessed via conditions/tpc/IndexDB

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Conditions-like Star DBs

• Access by time-stamp subsystem
• conditions/subsystem
• configurations/subsystem
• calibrations/subsystem
• geometry/subsystem

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Interface Questions

• What do you want? - making requests
• What do you get? - data container
• How to add new object type? - definition
  protocols
• How do you update? - db input protocols

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1) What do you want?

• Offline data is organized in Tree-Structure
• good idea - Online likes this too.
• Database-API Tree is shallow (2-levels)
• map to Tree structure at data access
• Database access is request retrieve process
• BdbDatabase-gtfetch(ObjH,indexContainer,theTime)
• Codes need to know what to request at object level

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Current Offline Model

• Objects are files in Tree-like file-system
• file-system catalog of available objects
• STAR/StDb/params/tpc/trspar/Trs.C
• A time-stamp in the filename for each instance
• myobject.time.C or myobject.time.xdf
• Upon request, all valid data in Tree is loaded
• other Makers get data from memory resident Tree

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Offline Interface Model

• St_DataSet ds GetDataBase(subtree-name)
• loads Tree-structure under subtree-name into db
  memory
• mdbds ds-gtFind(specific-name)
• gives St_A_Maker pointer to specific db data

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DB Interface Model

• StdbPtr mdbo factoryI-gtgetdbObject(name, time,
  version)

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DB Interface Model issue

• How does St_db_Maker know what to load?
• 1) StdbCatalogI mycat factoryI-gtgetCatalog()
• Catalog is Tree-Structured container of
• all available objects for this dbType.
• 2) StdbCatalogI mycat new StdbCatalog(file)
• file contains Tree-Structured container of
• objects as filtered for a specific Chain.

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DB Catalog Structure

• ltNodegt Geometry
• ltNodegt tpc
• ltobjectgt TPCPadPlanes lt/objectgt
• ltNodegt Sector_01
• ltobjectgt sectorPosition
• lt/objectgt lt/Nodegt
• ltNodegt Sector_02
• ltobjectgt sectorPositions ltversiongt V02
• lt/versiongt lt/objectgt lt/Nodegt lt/Nodegt
• lt/Nodegt
• ObjyObjectName tpcSector_01sectorPositions

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A Related Interface Issue

• How does St_db_Maker know to load my
• private test version of DB-data?
• factoryI-gtprependSearchPath(pathname)
• 1) Factory will use your path 1st to access
  db-data.
• 2) Data must be in the standard format Tree
• 3) St_db_Maker needs to call this function Not
  You.

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2) What do you get?
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DB Return-type StdbPtr

• Transient DB objects inherit from StdbPtr.
• StdbPtr contains a (list of) pointer to
  StdbObjectI.
• StdbObjectI defines methods
• getName(), getVersion(), getEndTime(), ...
• StdbPtr uses StdbObjectI to provide method
• bool isValid(time,version)
• St_DbSet (like St_ObjectSet) inherits from
  St_DataSet contains StdbPtr.

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What does this mean to you?

• Remember, we had
• St_DataSet ds GetDataBase(subtree-name)
• loads Tree-structure under subtree-name into db
  memory
• mdbds ds-gtFind(specific-name)
• mdb_table (my_table) mdbds-gtGetTable()
• gives St_A_Maker pointer to specific db data
• Now we have,
• St_DataSet ds GetDataBase(subtree-name)
• loads Tree-structure under subtree-name into db
  memory
• mdbds ds-gtFind(specific-name)
• mdbObj (DataObject )mdbds-gtGetdbObject()
• gives St_A_Maker pointer to specific db data

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Transient-Persistent Mismatch

• Efficient data storage suggests grouping
• data by function update frequency.
• This organization can be different than what
• user codes want.
• Who does copying from persistent structure
• to desirable transient structure?
• If Offline persistent -gt transient -gt better
  transient
• If DBInterface persistent -gt better transient

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Basic Model

• DB returns data Offl repacks into trans-DS
• Case UI-Object gtdbStuctA dbStructB
• StdbPtr mdbA factoryI-gtgetdbObject(A, time,
  version)
• StdbPtr mdbB factoryI-gtgetdbObject(B, time,
  version) .
• StDataObject mUI new StDataObject(mdbA, mdbB,
  .)
• mDataSet-gtAddObject(mUI)
• if(mdbA) delete mdbA if(mdbB) delete mdbB .
• St_db_Maker has to know about Data Objects
• DB does not.

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Alternative Model (in use)

• DB returns filled UI-Object as requested
• StdbPtr mUI factoryI-gtgetdbObject(name,
  time,version)
• mDataSet-gtAddObject(mUI)
• DB ( Catalog) has to know about Data Objects
• St_db_Maker does not.
• In the end, it should be done somewhere AND
• it shouldnt matter to user codes.

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3) How to add a new data type?

• Join starcalib-l meetings
• The process is not Templated yet.
• Also look at some current examples
• STAR_DB/DataBases/preStDb/Calib/...
• STAR/StDb/params/
• (STAR_DB is not on AFS but on rcf )

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in particular ...

• Work with calib/database group to add to
  Database.
• Define the data members needed
• typically one or more c-structs
• Define the UI object that is needed
• may be a simple table may be more complex
• Define a class that implements UI contains the
  data.

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4) How to update db-data?

• Protocols havent been defined. There
• will be some access restrictions on updates
• like Online authorization modes or CVS
• Private output via ROOT or XDF files
• migration step into the Database is a
• likely general solution.