8:33 a.m.
[
https://issues.jboss.org/browse/TEIID-4880?page=com.atlassian.jira.plugin...
]
Madou Coulibaly updated TEIID-4880:
-----------------------------------
Description:
Suppose we have the following star schema :
* Fact_Sales (Fact table)
* Dim_Date, Dim_Store and Dim_Product (Dimension tables)
Each table has a PK (id field)
Fact_Sales has a foreign key for each dimension (date_id, store_id, product_id) in order
to link them.
Then, suppose we create an aggregate view of the fact table and its dimensions:
_SELECT
*
FROM Fact_Sales F
INNER JOIN Dim_Date D ON (F.Date_Id = D.Id)
INNER JOIN Dim_Store S ON (F.Store_Id = S.Id)
INNER JOIN Dim_Product P ON (F.Product_Id = P.Id)_
Suppose now we only project fields from the fact table (Fact_Sales) and just one of its
dimension (Dim_Product) in a query:
_SELECT
Fact_Sales.<fields>, Dim_Product.<fields>
FROM aggregate_view_
During the Query Optimization, Teiid should be able to use the PK_FK constraints which
link the fact table with its dimension in order to deduct that no fields from the other
dimensions (Dim_Date, Dim_Store) are projected so the joins with these tables can be
removed for the Query Plan.
was:
Suppose we have the following star schema :
* Fact_Sales (Fact table)
* Dim_Date, Dim_Store and Dim_Product (Dimension tables)
Each table has a PK (id field)
Fact_Sales has a foreign key for each dimension (date_id, store_id, product_id) in order
to link them.
Then, suppose we create an aggregate view of the fact table and its dimensions:
SELECT
*
FROM Fact_Sales F
INNER JOIN Dim_Date D ON (F.Date_Id = D.Id)
INNER JOIN Dim_Store S ON (F.Store_Id = S.Id)
INNER JOIN Dim_Product P ON (F.Product_Id = P.Id)
Suppose now we only project fields from the fact table (Fact_Sales) and just one of its
dimension (Dim_Product) in a query:
SELECT
Fact_Sales.<fields>, Dim_Product.<fields>
FROM aggregate_view
During the Query Optimization, Teiid should be able to use the PK_FK constraints which
link the fact table with its dimension in order to deduct that no fields from the other
dimensions (Dim_Date, Dim_Store) are projected so the joins with these tables can be
removed for the Query Plan.
Join Elimination in Star Schema
-------------------------------
Key: TEIID-4880
URL: https://issues.jboss.org/browse/TEIID-4880
Project: Teiid
Issue Type: Feature Request
Components: Query Engine
Affects Versions: 8.7.11.6_2
Reporter: Madou Coulibaly
Assignee: Steven Hawkins
Suppose we have the following star schema :
* Fact_Sales (Fact table)
* Dim_Date, Dim_Store and Dim_Product (Dimension tables)
Each table has a PK (id field)
Fact_Sales has a foreign key for each dimension (date_id, store_id, product_id) in order
to link them.
Then, suppose we create an aggregate view of the fact table and its dimensions:
_SELECT
*
FROM Fact_Sales F
INNER JOIN Dim_Date D ON (F.Date_Id = D.Id)
INNER JOIN Dim_Store S ON (F.Store_Id = S.Id)
INNER JOIN Dim_Product P ON (F.Product_Id = P.Id)_
Suppose now we only project fields from the fact table (Fact_Sales) and just one of its
dimension (Dim_Product) in a query:
_SELECT
Fact_Sales.<fields>, Dim_Product.<fields>
FROM aggregate_view_
During the Query Optimization, Teiid should be able to use the PK_FK constraints which
link the fact table with its dimension in order to deduct that no fields from the other
dimensions (Dim_Date, Dim_Store) are projected so the joins with these tables can be
removed for the Query Plan.
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