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ba9b78c103
This patch adds new built-in functions to calculate Levenshtein edit distance. Implemented as levenshtein() to match PostgreSQL in both functionality and name and also added le_dst() alias for Netezza, compatibility, but note that levenshtein() differs in functionality in that if either value is NULL or both values are NULL, levenshtein() returns NULL, where Netezza's le_dst() returns the length of the not NULL value or 0 if both values are NULL. Testing: - Added unit tests to expr-test.cc - Manual test on 966289 string pairs and results match PostgreSQL - Added changes to qgen tests for PostgreSQL comparison Change-Id: I549d33ab7cebfa10db2934461c8ec91e2cc1cdcb Reviewed-on: http://gerrit.cloudera.org:8080/11793 Reviewed-by: Tim Armstrong <tarmstrong@cloudera.com> Tested-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>