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Alex Rodoni commented on IMPALA-7739: ------------------------------------- https://gerrit.cloudera.org/#/c/11758/ > Errata in documentation of decode() method > ------------------------------------------ > > Key: IMPALA-7739 > URL: https://issues.apache.org/jira/browse/IMPALA-7739 > Project: IMPALA > Issue Type: Improvement > Components: Docs > Affects Versions: Impala 3.0 > Reporter: Paul Rogers > Assignee: Alex Rodoni > Priority: Minor > > Consider the description of {{decode()}} in [the > docs|https://impala.apache.org/docs/build3x/html/topics/impala_conditional_functions.html]. > Original text: > {quote} > decode(type expression, type search1, type result1 [, type search2, type > result2 ...] [, type default] ) > Purpose: Compares an expression to one or more possible values, and returns a > corresponding result when a match is found. > Return type: same as the initial argument value, except that integer values > are promoted to BIGINT and floating-point values are promoted to DOUBLE; use > CAST() when inserting into a smaller numeric column > Usage notes: > * Can be used as shorthand for a CASE expression. > * The original expression and the search expressions must of the same type or > convertible types. * The result expression can be a different type, but all > result expressions must be of the same type. > * Returns a successful match If the original expression is NULL and a search > expression is also NULL. the > * Returns NULL if the final default value is omitted and none of the search > expressions match the original expression. > {quote} > Revise: > * Remove “type” prefix for arguments (here and in all functions), it really > adds no value and is actually confusing because the argument is not a type, > it is a value. > * Usage notes: Comparison is done using the IS NOT DISTINCT (<=>) operator: > this NULL can be used as a search condition. > * Since this is a list, great between the two items in the second item in > usage. > * The third item has a dangling “the” at the end. > * Reword the fourth item: “If none of the search expressions match the > expression, then returns the default (if given) or NULL (if no default is > given.)” > Suggested revised text: > Purpose: Compares an expression to one or more possible values using the IS > NOT DISTINCT operator, and returns a corresponding result when a match is > found. > Usage notes: > * Can be used as shorthand for a CASE expression. > * The expression and the search expressions must of the same type or > convertible types. > * The result expression can be a different type, but all result expressions > must be of the same type. > * Returns a successful match If the original expression is NULL and a search > expression is also NULL. (Uses IS NOT DISTINCT to do the comparison.) > * NULL can be used as a search expression. > * Returns NULL if the final default value is omitted and none of the search > expressions match the original expression. -- This message was sent by Atlassian JIRA (v7.6.3#76005) --------------------------------------------------------------------- To unsubscribe, e-mail: issues-all-unsubscr...@impala.apache.org For additional commands, e-mail: issues-all-h...@impala.apache.org