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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>
49 lines
2.2 KiB
Python
49 lines
2.2 KiB
Python
# Licensed to the Apache Software Foundation (ASF) under one
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# or more contributor license agreements. See the NOTICE file
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# distributed with this work for additional information
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# regarding copyright ownership. The ASF licenses this file
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# to you under the Apache License, Version 2.0 (the
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# "License"); you may not use this file except in compliance
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# with the License. You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing,
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# software distributed under the License is distributed on an
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# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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# KIND, either express or implied. See the License for the
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# specific language governing permissions and limitations
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# under the License.
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# The purpose of this module is to unify a place to settle DB differences in addition to
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# differences based on DB API2 libraries (like Impyla vs. psycopg2). Putting the
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# handling in a single place will make it easier to track what workarounds exist.
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from tests.comparison import db_connection
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def setup_ref_database(ref_conn):
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"""Set up reference database at query generator runtime.
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Because data_generator.py runs are expensive operations, and reference databases tend
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to persist across runs, this method should support lightweight options to configure
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reference databases as needed, regardless of whether the data is loaded or not. A good
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example is loading optional PostgreSQL modules to support comparison with functions
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added to Impala.
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ref_conn: Open db_connection.DbConnection object. Method assumes no open cursors on
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open connection object. Method will close any cursors opened, and leave connection
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open.
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"""
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if ref_conn.db_type == db_connection.POSTGRESQL:
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# IMPALA-7759: The Levenshtein function needs the fuzzystrmatch extension.
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# References:
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# https://www.postgresql.org/docs/9.5/fuzzystrmatch.html
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# https://www.postgresql.org/docs/9.5/sql-createextension.html
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# On Ubuntu 16, postgresql-contrib-9.5 provides fuzzystrmatch and is installed as
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# part of Impala's bin/bootstrap_system.sh.
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with ref_conn.cursor() as cursor:
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cursor.execute('CREATE EXTENSION IF NOT EXISTS fuzzystrmatch')
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