[teiid-issues] [JBoss JIRA] (TEIID-4452) Pushdown SQL/XML
Tom Arnold (JIRA)
issues at jboss.org
Mon Sep 19 10:55:01 EDT 2016
Tom Arnold created TEIID-4452:
---------------------------------
Summary: Pushdown SQL/XML
Key: TEIID-4452
URL: https://issues.jboss.org/browse/TEIID-4452
Project: Teiid
Issue Type: Enhancement
Components: JDBC Connector
Affects Versions: 9.x
Reporter: Tom Arnold
Assignee: Steven Hawkins
It would be helpful to pushdown SQL/XML functions for JDBC databases that support them.
Databases:
- Oracle
- Postgres
Functions:
- XMLELEMENT
- XMLATTRIBUTES
- XMLAGG
- XMLCONCAT
We have an application that uses these functions and we support Oracle, Postgres, and Teiid (to integrate external data sources). Here's an example query generated by this application:
{code:xml}
select
"ITEMS"."ITEM_ID" "ITEM_ID",
(
select xmlelement (
name "attributes",
xmlagg(
xmlelement(
name "attribute",
xmlattributes(
"ITEM_ATTRIBUTES"."ATTR_NAME" as "name",
"ITEM_ATTRIBUTES"."ATTR_VALUE" as "value"
)
)
)
)
from "ITEM_ATTRIBUTES" "ITEM_ATTRIBUTES"
where (
"ITEMS"."ITEM_ID" = "ITEM_ATTRIBUTES"."ITEM_ID"
)
) "ITEM_ATTRIBUTES"
{code}
{code}
ITEM_ID ITEM_ATTRIBUTES
3 <attributes><attribute name="foo" value="bar"></attribute><attribute name="baz" value="blah"></attribute></attributes>
4 <attributes><attribute name="foo" value="123"></attribute><attribute name="baz" value="456"></attribute></attributes>
{code}
When we are using Teiid queries like this do not work well because they cannot be pushed down, so we get N-many queries (one per row) and the query ends up taking much longer than if performed directly against Oracle/Postgres.
Since SQL/XML is standard and supported by both Oracle/Postgres it would be good if queries like this could be pushed in their entirety so that there would be no performance difference between going through Teiid and native.
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