[jira] [Resolved] (ASTERIXDB-2272) Change character positions inside a string from 1-based to 0-based

["Dmitry Lychagin (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/ASTERIXDB-2272?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Dmitry Lychagin resolved ASTERIXDB-2272.
----------------------------------------
    Resolution: Fixed

> Change character positions inside a string from 1-based to 0-based
> ------------------------------------------------------------------
>
>                 Key: ASTERIXDB-2272
>                 URL: https://issues.apache.org/jira/browse/ASTERIXDB-2272
>             Project: Apache AsterixDB
>          Issue Type: Improvement
>          Components: FUN - Functions
>            Reporter: Dmitry Lychagin
>            Assignee: Dmitry Lychagin
>            Priority: Minor
>
> Change how string functions count character positions inside a string.
> Currently string functions position(), substring() and some others assume that the first character is at position 1.
> The proposal is to change the first position to 0, to better align with array element positions (which also start with 0), and other languages.
> This change will also apply to binary functions (below) and will be effective in both SQLPP and AQL.
>  
> The following functions will be affected:
> position(),
> regexp_position(),
> substring()/substr(),
> sub_binary(),
> find_binary()
>  
> This might be a disrupting change for some users so we will also introduce a cluster-wide configuration parameter (“compiler.stringoffset”) for backwards compatibility:
> compiler.stringoffset = 0   // first character position is assumed to be 0 (new default)
> compiler.stringoffset = 1   // first character position is assumed to be 1 (backwards-compatible setting)
>  
> The query migration path is straightforward, for example:
> substring(“abcdef”, 1) will need to be changed to substring(“abcdef”, 0), etc, same applies to sub_binary().
> position(), regexp_position(), and find_binary() will return one less than they used to, but would still return -1 if the value is not found.



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