techdocsmith commented on code in PR #16704: URL: https://github.com/apache/druid/pull/16704#discussion_r1681910026
########## docs/release-info/migr-ansi-sql-null.md: ########## @@ -0,0 +1,266 @@ +--- +id: migr-ansi-sql-null +title: "Migration guide: SQL compliant mode" +sidebar_label: SQL compliant mode +--- + +<!-- + ~ 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. +--> +import Tabs from '@theme/Tabs'; +import TabItem from '@theme/TabItem'; + +In Apache Druid 28.0.0, the default [null handling](../querying/sql-data-types.md#null-values) mode changed to be compliant with the SQL standard: + +The SQL standard defines any comparison to null to be unknown. +Therefore, according to this three-value logic, `x <> 'some value'` only returns non-null values. + +Now, Druid stores segments in a SQL compatible null handling mode by default. + +The default Druid configurations for SQL compatible null handling mode is as follows: + +* `druid.generic.useDefaultValueForNull=false` +* `druid.expressions.useStrictBooleans=true` +* `druid.generic.useThreeValueLogicForNativeFilters=true` + +Note Druid has always applied three-value logic by default to expressions. +Therefore, queries such as `(x+y) <> ‘some value’` exclude null values even prior to Druid 28.0.0. Review Comment: I removed this. It seems like it is not necessary for this topic. -- 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]
