clintropolis commented on a change in pull request #9638: URL: https://github.com/apache/druid/pull/9638#discussion_r472821403
########## File path: core/src/main/java/org/apache/druid/segment/column/ValueType.java ########## @@ -0,0 +1,68 @@ +/* + * 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. + */ + +package org.apache.druid.segment.column; + +import com.fasterxml.jackson.annotation.JsonCreator; +import org.apache.druid.java.util.common.StringUtils; + +import javax.annotation.Nullable; + +public enum ValueType +{ + DOUBLE, + FLOAT, + LONG, + STRING, + COMPLEX, + DOUBLE_ARRAY, + LONG_ARRAY, + STRING_ARRAY; Review comment: Not sure yet, I'm still thinking on the best way to live in a world with the current `STRING` that can have single or multi values, communicated through `ColumnCapabilities.hasMultipleValues`, and `STRING_ARRAY` which is explicitly always multi-valued but can currently only be produced via expressions. I think it depends on how we want to encode this information for `RowSignature` to make available to the broker and higher layers of the query engines. There might be room for a new `ValueType` to use explicitly for `STRING` which are multi-valued if we want to keep `RowSignature` light (and effectively coerce it back to `STRING` when translating the signature back into `ColumnCapabilities` for things like the row selectors the broker uses), though between the changes in #10219 which also adds a want to be able to encode in the `RowSignature` which columns can have null values, making a richer `RowSignature` is probably the right way forward, which could potentially make a separate `ValueType` for multi-value strings not necessary. I don't think we want to treat the multi-value strings as `STRING_ARRAY` because I think we probably want to reserve it for if/when we add true array typed columns, so that engines like group by and top-n can process them separately than the funny way we handle existing multi-value strings (which aggregate on individual values, basically equivalent to `UNNEST` in SQL) and instead do it in a way that is compatible with SQL array types. ---------------------------------------------------------------- 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. For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
