The data model

The ALICE O2 data model is a collection of tables. This includes tables which are read from the input files AO2D files and also such which are created by tasks. To produce some tables with commonly used quantities there exist a set of predefined helper tasks which can be included in user analysis work flows to produce tables with commonly used information

The data model also provides a bunch of pre-defined joins and iterators.

Table relations

Information contained in different tables can be related. E.g. a track belongs to a given collision, or signals in the FIT or Zdc detectors belong to a bunch crossing.

Hence the dependent tables need to hold an index which points to a specific row of the master table. For this the dependent table (e.g. table Tracks) has an index column [master]Id (in this case CollisionsId) which points to the related information in table master. See also e.g. master=BCs and dependent=CaloTriggers and many more.

Note

Be aware that tables can be joined and be extended with extra colums.

In the table listings on the following pages, the letter in brackets behind the table name indicates the type of table:

  • E: extended table
  • I: index table
  • else: normal table

And similar for the columns:

  • D: dynamic column
  • E: expression column
  • GI: global index
  • I: index column
  • else: normal column