Fix contrib/pg_trgm's similarity() function for trigram-free strings.
Cases such as similarity('', '') produced a NaN result due to computing
0/0. Per discussion, make it return zero instead.
This appears to be the basic cause of bug #7867 from Michele Baravalle,
although it remains unclear why her installation doesn't think Cyrillic
letters are letters.
Back-patch to all active branches.
Branch
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REL9_2_STABLE
Details
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http://git.postgresql.org/pg/commitdiff/7b058a2dc8fd5889cd443fd6ee40f51068357245
Modified Files
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contrib/pg_trgm/expected/pg_trgm.out | 6 ++++++
contrib/pg_trgm/sql/pg_trgm.sql | 2 ++
contrib/pg_trgm/trgm_op.c | 8 ++++++--
3 files changed, 14 insertions(+), 2 deletions(-)