[GitHub] [iceberg] kbendick commented on a change in pull request #2761: Add an implemention of STARTS_WITH for Python API.

[GitBox <gi...@apache.org>]

kbendick commented on a change in pull request #2761:
URL: https://github.com/apache/iceberg/pull/2761#discussion_r678890318



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File path: python/iceberg/api/expressions/expression_parser.py
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@@ -44,7 +44,7 @@
 ident = Word(alphas, alphanums + "_$").setName("identifier")
 columnName = delimitedList(ident, ".", combine=True).setName("column name")
 
-binop = oneOf("= == != < > >= <= eq ne lt le gt ge <>", caseless=False)
+binop = oneOf("= == != < > >= <= eq ne lt le gt ge <> startsWith", caseless=False)

Review comment:
       Would it make sense to allow for `starts_with` in the expression parser too? The SQL wouldn't exactly be portable outside of PySpark etc, but users might want to use the language natural `starts_with` and we already have `lt` `le` and their counterparts `<` `<=` etc.

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File path: python/iceberg/api/expressions/inclusive_manifest_evaluator.py
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@@ -159,3 +159,7 @@ def in_(self, ref, lit):
 
     def not_in(self, ref, lit):
         return ROWS_MIGHT_MATCH
+
+    def starts_with(self, ref, lit):
+        # if it's all null then we can't match :)
+        return self.not_null(ref)

Review comment:
       Most of the functions seem to explicitly return the constants `ROWS_MIGHT_MATCH` and `ROWS_CANNOT_MATCH`. Would this fit in more as `return ROWS_CANNOT_MATCH if self.not_null(ref) else ROWS_MIGHT_MATCH` or similar?




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