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proposal: prefix function - Mailing list pgsql-hackers

From Pavel Stehule
Subject proposal: prefix function
Date
Msg-id CAFj8pRDj04axPu2GgR8fDouDHLfxzyzcdqS0c+NOSfxJkYbRFQ@mail.gmail.com
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Responses Re: proposal: prefix function  (Chris Travers <chris.travers@adjust.com>)
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Hi

can we implement prefix function for fast test if substr is prefix of some string?

create or replace function prefix(str text, substr text)
returns boolean as $$
  select substr(str, 1, length(substr)) = substr
$$ language sql;

This function can be very effective in C language. Now it should be implemented with like or regexp, what is significantly more expensive.

Regards

Pavel

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