I asked ChatGPT:
in a union in denodo, what does this association mean? (bv_slate_tuv_person.slatepersonrefid = bv_slate_tuh_person.slatepersonrefid AND bv_slate_tuv_person.slatepersonrefid = bv_slate_tuf_person.slatepersonrefid AND bv_slate_tuv_person.slatepersonrefid = bv_slate_tup_person.slatepersonrefid)
ChatGPT said:
In Denodo, the expression you've provided appears to be part of a union operation where multiple base views are combined, and specific associations between fields are being established. Let's break down what this association means: Components of the Expression:
bv_slate_tuv_person: A base view in Denodo.
slatepersonrefid: A field (likely a unique identifier or a key) in the bv_slate_tuv_person view.
Other Views:
bv_slate_tuh_person
bv_slate_tuf_person
bv_slate_tup_person
Each of these views also has a slatepersonrefid field. Meaning of the Association:
Equality Conditions: The expression is asserting that the slatepersonrefid field in the bv_slate_tuv_person view must be equal to the slatepersonrefid fields in each of the other views (bv_slate_tuh_person, bv_slate_tuf_person, bv_slate_tup_person). This could be part of: Union Operation: Ensuring that records being combined across these views are related by the same slatepersonrefid.
Data Integrity: Making sure that the slatepersonrefid is consistent across these views, which might be necessary for joining or combining the data meaningfully.
Implications:
Data Consistency: This ensures that all the views are aligned based on the slatepersonrefid, likely representing the same entity (e.g., a person) across different datasets.
Union Specificity: The union will only combine rows where the slatepersonrefid matches across all the views, which is important for maintaining data integrity and correctness.
Example Use Case:
You might have different views representing different aspects of a person's data (like address, job, etc.). By associating them through the slatepersonrefid, you ensure that all information combined in the union corresponds to the same individual.
In summary, this association is used to ensure that the slatepersonrefid field consistently matches across the views involved in the union, thereby maintaining the integrity of the combined dataset. You said:
if the denodo association contains the following expressions: (bv_slate_tuv_person.slatepersonrefid = bv_slate_tuh_person.slatepersonrefid AND bv_slate_tuv_person.slatepersonrefid = bv_slate_tuf_person.slatepersonrefid AND bv_slate_tuv_person.slatepersonrefid = bv_slate_tup_person.slatepersonrefid)
(bv_slate_tuv_person.createddate = bv_slate_tuh_person.createddate AND bv_slate_tuv_person.createddate = bv_slate_tuf_person.createddate AND bv_slate_tuv_person.createddate = bv_slate_tup_person.createddate) , does that mean only rows that have identical values across both slatepersonrefid and createddate?
ChatGPT said:
Yes, the expressions provided indicate that only rows with identical values across both slatepersonrefid and createddate fields will be considered in the association. Here's a breakdown of how this works: Expressions Recap:
Slatepersonrefid Matching:
bv_slate_tuv_person.slatepersonrefid = bv_slate_tuh_person.slatepersonrefid
AND bv_slate_tuv_person.slatepersonrefid = bv_slate_tuf_person.slatepersonrefid
AND bv_slate_tuv_person.slatepersonrefid = bv_slate_tup_person.slatepersonrefid Createddate Matching:
bv_slate_tuv_person.createddate = bv_slate_tuh_person.createddate
AND bv_slate_tuv_person.createddate = bv_slate_tuf_person.createddate
AND bv_slate_tuv_person.createddate = bv_slate_tup_person.createddate
Interpretation:
slatepersonrefid Matching: Ensures that the slatepersonrefid field (likely a unique identifier) in bv_slate_tuv_person matches the slatepersonrefid field in all other views (bv_slate_tuh_person, bv_slate_tuf_person, bv_slate_tup_person). createddate Matching: Ensures that the createddate field (likely a timestamp or date of creation) in bv_slate_tuv_person matches the createddate field in all the other views. Combined Effect:
Both Conditions Must Be True: For any row to be included in the result set, both the slatepersonrefid and createddate fields must match across all the views. This means:
If any of these fields have differing values in any of the views, those rows will be excluded from the result.
Only rows with matching slatepersonrefid and createddate across all views will be included.
Result:
In summary, yes, the provided association expressions ensure that only rows with identical values in both slatepersonrefid and createddate across all specified views will be included in the result. With Matt in Teams: (bv_slate_tuv_person.slatepersonrefid = bv_slate_tuh_person.slatepersonrefid AND bv_slate_tuv_person.slatepersonrefid = bv_slate_tuf_person.slatepersonrefid AND bv_slate_tuv_person.slatepersonrefid = bv_slate_tup_person.slatepersonrefid) This is the first association in the u_slate_person union. I understand that the union is a combination of the base view tables for tuv, tuh, tuf, and tup, returning one row for each distinct slatepersonrefid. We expect that to return one row for each person in each database, and will be very sad if there are ever any duplicates. Is this expression saying that the only condition under which any records in these four databases would be combined in the union is if there is a single record in all four databases with the exact same slatepersonrefid? If I have got that correct, since there are associations like that for each field, that the only way any merging records can happen is that if literally every single field was the same across all four base views? No. The union being done in Denodo is a UNION ALL, which just joins the views together row-rise, there’s no special logic. If you have 6 views, 500 rows each, you end up with 3000 rows. I think that join you see is an abitrary column that Denodo picks that all views had in common to syntactically “join” the views together in VQL. But the contents of that column have no bearing on the output. ohhh, so that wasn't something you built Sort of. When you build things graphically Denodo generates VQL for you to represent what you built. |