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https://issues.apache.org/jira/browse/IMPALA-14869?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jason Fehr updated IMPALA-14869:
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Description:
When predicates exist that do case insensitive text comparison by calling
functions such as `UPPER()` or `LOWER()`, those predicates must allocate
additional memory for the result string.
Identify all places where functions that allocate memory can be replaced with
`ILIKE` or `IREGEXP`. Performance test to determine If replacing these
functions will improve performance.
Re-write these types of predicates to use the [ILIKE or IREGEXP
operator|https://impala.apache.org/docs/build/html/topics/impala_string_functions.html#string_functions__lower:~:text=Usage%20notes%3A-,In%20Impala%202.5%20and%20higher%2C%20you%20can%20simplify%20queries%20that%20use%20many%20UPPER()%20and%20LOWER()%20calls%20to%20do%20case%2Dinsensitive%20comparisons%2C%20by%20using%20the%20ILIKE%20or%20IREGEXP%20operators%20instead.%20See%20ILIKE%20Operator%20and%20IREGEXP%20Operator%20for%20details.,-LPAD(STRING%20str]
was:
When predicates exist that do case insensitive text comparison by calling
functions such as `UPPER()` or `LOWER()`, those predicates must allocate
additional memory for the result string.
Identify all places where functions that allocate memory can be replaced with
`ILIKE` or `IREGEXP`. Performance test to determine If replacing these
functions will improve performance.
Re-write these types of predicates to use the [ILIKE or IREGEXP
operator](https://impala.apache.org/docs/build/html/topics/impala_string_functions.html#string_functions__lower:~:text=Usage%20notes%3A-,In%20Impala%202.5%20and%20higher%2C%20you%20can%20simplify%20queries%20that%20use%20many%20UPPER()%20and%20LOWER()%20calls%20to%20do%20case%2Dinsensitive%20comparisons%2C%20by%20using%20the%20ILIKE%20or%20IREGEXP%20operators%20instead.%20See%20ILIKE%20Operator%20and%20IREGEXP%20Operator%20for%20details.,-LPAD(STRING%20str)
> Rewrite Case Insensitive Predicates
> -----------------------------------
>
> Key: IMPALA-14869
> URL: https://issues.apache.org/jira/browse/IMPALA-14869
> Project: IMPALA
> Issue Type: Improvement
> Affects Versions: Impala 4.5.0
> Reporter: Jason Fehr
> Priority: Critical
>
> When predicates exist that do case insensitive text comparison by calling
> functions such as `UPPER()` or `LOWER()`, those predicates must allocate
> additional memory for the result string.
> Identify all places where functions that allocate memory can be replaced with
> `ILIKE` or `IREGEXP`. Performance test to determine If replacing these
> functions will improve performance.
> Re-write these types of predicates to use the [ILIKE or IREGEXP
> operator|https://impala.apache.org/docs/build/html/topics/impala_string_functions.html#string_functions__lower:~:text=Usage%20notes%3A-,In%20Impala%202.5%20and%20higher%2C%20you%20can%20simplify%20queries%20that%20use%20many%20UPPER()%20and%20LOWER()%20calls%20to%20do%20case%2Dinsensitive%20comparisons%2C%20by%20using%20the%20ILIKE%20or%20IREGEXP%20operators%20instead.%20See%20ILIKE%20Operator%20and%20IREGEXP%20Operator%20for%20details.,-LPAD(STRING%20str]
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