Horton

Handle empty-string edge cases correctly in strpos().

Tom Lane <tgl@sss.pgh.pa.us>

View on postgr.es
Commit: 43e43771bc4b03a9e33be7261cc84dc7f65ae9ef
Author: Tom Lane <tgl@sss.pgh.pa.us>
Date: 2019-10-28T16:21:13Z
Releases: 12.1 
Handle empty-string edge cases correctly in strpos().

Commit 9556aa01c rearranged the innards of text_position() in a way
that would make it not work for empty search strings.  Which is fine,
because all callers of that code special-case an empty pattern in
some way.  However, the primary use-case (text_position itself) got
special-cased incorrectly: historically it's returned 1 not 0 for
an empty search string.  Restore the historical behavior.

Per complaint from Austin Drenski (via Shay Rojansky).
Back-patch to v12 where it got broken.

Discussion: https://postgr.es/m/CADT4RqAz7oN4vkPir86Kg1_mQBmBxCp-L_=9vRpgSNPJf0KRkw@mail.gmail.com

Files

PathChange+/−
src/backend/utils/adt/varlena.c modified +9 −1
src/test/regress/expected/strings.out modified +18 −0
src/test/regress/sql/strings.sql modified +6 −0

Discussion