Hello Madhan,
I am working my way through the open metadata model and working out how to
stitch it to the existing structures. I wanted to be sure I am
understanding the JSON properly
I am looking in addons/models/0030-hive_model.json at the relationships
between hive_table and hive_column, hive_db. All of these are entities.
Firstly, hive_table declares an attribute called db of type hive_db: There
is no ownedRef entry nor a matching entry in the hive_db definition so I
am assuming that db is just a complex atribute and there is no navigation
from hive_db to hive_table? What is the difference between defining
hive_db as an entity rather than a struct?
{
"name": "hive_table",
"superTypes": [
"DataSet"
],
"typeVersion": "1.0",
"attributeDefs": [
{
"name": "db",
"typeName": "hive_db",
"cardinality": "SINGLE",
"isIndexable": false,
"isOptional": false,
"isUnique": false
},
:
}
Next, hive_table seems to have a 2 way composition relationships between
itself and hive_column called columns<->table. These are definitions for
the relationship in these entities:
{
"name": "hive_table",
"superTypes": [
"DataSet"
],
"typeVersion": "1.0",
"attributeDefs": [
:
{
"name": "columns",
"typeName": "array<hive_column>",
"cardinality": "SINGLE",
"constraints": [
{
"type": "ownedRef"
}
],
"isIndexable": false,
"isOptional": true,
"isUnique": false
},
:
:
]
},
{
"name": "hive_column",
"superTypes": [
"DataSet"
],
"typeVersion": "1.0",
"attributeDefs": [
:
{
"name": "table",
"typeName": "hive_table",
"cardinality": "SINGLE",
"constraints": [
{
"type": "inverseRef",
"params": {
"attribute": "columns"
}
}
],
"isIndexable": false,
"isOptional": true,
"isUnique": false
}
]
},
However, a similar definition in hive_table for partitionKeys does not
have an inverseRef entry in hive_column - does that make it one way? What
does the "OwnedRef" declaration do in this case?
{
"name": "hive_table",
"superTypes": [
"DataSet"
],
"typeVersion": "1.0",
"attributeDefs": [
:
:
{
"name": "partitionKeys",
"typeName": "array<hive_column>",
"cardinality": "SINGLE",
"constraints": [
{
"type": "ownedRef"
}
],
"isIndexable": false,
"isOptional": true,
"isUnique": false
},
:
:
]
},
Is there any difference in the behaviour of the relationship called db (to
hive_db) and the one called partitionKeys?
This is the UML I have derived
Also, do you have example JSON structures for classifications?
Many thanks for your help
All the best
Mandy
___________________________________________
Mandy Chessell CBE FREng CEng FBCS
IBM Distinguished Engineer
Master Inventor
Member of the IBM Academy of Technology
Visiting Professor, Department of Computer Science, University of
Sheffield
Email: mandy_chess...@uk.ibm.com
LinkedIn: http://www.linkedin.com/pub/mandy-chessell/22/897/a49
Assistant: Janet Brooks - jsbrook...@uk.ibm.com
