Dandandan commented on a change in pull request #422:
URL: https://github.com/apache/arrow-datafusion/pull/422#discussion_r638981442
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File path: docs/rfcs/output-field-name-semantic.md
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+# Datafusion output field name semantic
+
+Start Date: 2020-05-24
+
+## Summary
+
+Formally specify how Datafusion should construct its output field names based
on
+provided user query.
+
+## Motivation
+
+By formalizing the output field name semantic, users will be able to access
+query output using consistent field names.
+
+## Detailed design
+
+The proposed semantic is chosen for the following reasons:
+
+* Ease of implementation, field names can be derived from physical expression
+without having to add extra logic to pass along arbitrary user provided input.
+Users are encouraged to use ALIAS expressions for full field name control.
+* Mostly compatible with Spark’s behavior except literal string handling.
+* Mostly backward compatible with current Datafusion’s behavior other than
+function name cases and parenthesis around operator expressions.
+
+### Field name rules
+
+* All field names MUST not contain relation qualifier.
+ * Both `SELECT t1.id` and `SELECT id` SHOULD result in field name: `id`
+* Function names MUST be converted to lowercase.
+ * `SELECT AVG(c1)` SHOULD result in field name: `avg(c1)`
Review comment:
MariaDB:
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