8. Data Management Advanced

This section shows how the File Catalog can be used as a Metadata Catalog. The exercises are performed using the File Catalog CLI interface. You can start the CLI with the command:


8.1 User metadata

Metadata is the information describing the user data in order to easily select the data sets of interest for user applications. In the DIRAC File Catalog metadata can be associated with any directory. It is important that subdirectories are inheriting the metadata of their parents, this allows to reduce the number of the stored metadata values. Some metadata variables can be declared as indices. Only indexed metadata can be used in data selections.

  • Adding metadata to a directory:

    meta set  <directory> <metaname> <metavalue>

    For example:

    FC:/vo.formation.idgrilles.fr/user/a/atsareg>meta set . ATMetaStr Test
    FC:/vo.formation.idgrilles.fr/user/a/atsareg>mkdir testDir
    Successfully created directory: /vo.formation.idgrilles.fr/user/a/atsareg/testDir
    FC:/vo.formation.idgrilles.fr/user/a/atsareg>meta set testDir AnotherMeta AnotherTest
  • Getting directory metadata:

    meta get <directory>

    For example:

    FC:/vo.formation.idgrilles.fr/user/a/atsareg>meta get testDir
            AnotherMeta : AnotherTest
              ATMetaStr : Test
  • Creating metadata index:

    meta index <metaname> <metatype>

    For example:

    FC:/vo.formation.idgrilles.fr/user/a/atsareg>meta index NewMetaInt int
    Added metadata field NewMetaInt of type int

    Possible metadata types: int,float,string,date

  • Showing existing metadata indices:

    meta show

    For example:

    FC:/vo.formation.idgrilles.fr/user/a/atsareg>meta show
            ATMetaStr : VARCHAR(128)
            ATMetaInt : INT
           ATMetaDate : DATETIME
            ATMetaSet : MetaSet
           ATMetaInt1 : INT
           NewMetaInt : INT
            ATMetaFlt : float
  • Finding files with selection by metadata:

    find <meta selection>

    For example:

    FC:/vo.formation.idgrilles.fr/user/a/atsareg> find ATMetaInt=10,11 ATMetaInt1<15
    Query: {'ATMetaInt': {'in': [10, 11]}, 'ATMetaInt1': {'<': 15}}

8.2 File Provenance Metadata

In the File Catalog you can declare ancestor files for a given file. This is often needed in order to keep track of the derived data provenance path. The ancestor declaration is done as following:

ancestorset <descendent> <ancestor>

For example:

FC:/vo.formation.idgrilles.fr/user/a/atsareg> ancestorset file2 file1
FC:/vo.formation.idgrilles.fr/user/a/atsareg> ancestorset file3 file2

Once the chain of ancestors/descendents is created it can be interrogated with the following commands:

ancestor <file> <depth>
descendent <file> <depth>

For example:

FC:/vo.formation.idgrilles.fr/user/a/atsareg> ancestor file3 2
1      /vo.formation.idgrilles.fr/user/a/atsareg/file2
2              /vo.formation.idgrilles.fr/user/a/atsareg/file1

FC:/vo.formation.idgrilles.fr/user/a/atsareg> descendent file1 2
1      /vo.formation.idgrilles.fr/user/a/atsareg/file2
2              /vo.formation.idgrilles.fr/user/a/atsareg/file3