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https://issues.jboss.org/browse/TEIID-2858?page=com.atlassian.jira.plugin...
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Tom Johnston commented on TEIID-2858:
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As a general rule any function will negate the use of any index on the field. Though there
are "function-based-indexes" these are not options with COTS products. Some
consideration must be made when a potential fix has ramifications that would diminish the
performance. "Middleware" already has something to prove when it comes to NOT
heavily impacting performance so let's not purposely do something that can impact
performance.
Database use of char[>1] cause using Convert(x,x) and negates
using an index
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Key: TEIID-2858
URL:
https://issues.jboss.org/browse/TEIID-2858
Project: Teiid
Issue Type: Bug
Components: Misc. Connectors
Affects Versions: 8.4.1
Reporter: Van Halbert
Assignee: Steven Hawkins
When a database defines a char of length greater than 1, a convert(x,x) is being used in
the criteria, and thereby, negating the use of an index and causing table scans.
Note: There is no option to change the database schemas, because they are from a COTS
product.
I would think there needs to be a solution in the translator such that if it can be
detected that its for a char column and that it does not do the convert.
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