findepi commented on code in PR #13706: URL: https://github.com/apache/datafusion/pull/13706#discussion_r1880215242
########## docs/source/user-guide/sql/dialect.md: ########## @@ -0,0 +1,38 @@ +<!--- + Licensed to the Apache Software Foundation (ASF) under one + or more contributor license agreements. See the NOTICE file + distributed with this work for additional information + regarding copyright ownership. The ASF licenses this file + to you under the Apache License, Version 2.0 (the + "License"); you may not use this file except in compliance + with the License. You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, + software distributed under the License is distributed on an + "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + KIND, either express or implied. See the License for the + specific language governing permissions and limitations + under the License. +--> + +# SQL Dialect + +By default, Apache DataFusion follows the [PostgreSQL SQL dialect]. +For Array/List functions and semantics, it follows the [DuckDB SQL dialect]. + +[duckdb sql dialect]: https://duckdb.org/docs/sql/functions/array +[postgresql sql dialect]: https://www.postgresql.org/docs/current/sql.html Review Comment: > Creating a new dialect that we feel is better - but now users have to learn that dialect and we have to define exactly what it means I also would prefer to avoid doing that. But in fact we're doing exactly that. It's a stretch to pretend we're not shipping "DataFusion's dialect of SQL". > I think it we could just say "do whatever DuckDB does in this case" that would be much more efficent and the PR would not get stuck Yes, that's efficient. But same efficiency you get from "do whatever PostgreSQL does" (efficiency in terms of answering on-PR design questions) And same efficiency you get from "do whatever Trino does" We're trading answer efficiency vs consistency and predictability of our of the box semantics, with both sides of the trade being desirable properties. It's likely that maximum consistency you get from "do whatever SQL spec says", but obviously this isn't very efficient (most engineers can't even read the spec). > Following an existing non ideal dialect (all existing dialects are non ideal) - which is predictable, and easier (we don't have to figure out semantics) That would be great, especially if this a reasonable dialect (some are, some are not) and is one dialect, not some form of a synergy between two different dialects that disagree with each other. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
