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Posted to dev@iceberg.apache.org by GitBox <gi...@apache.org> on 2022/04/03 22:21:09 UTC
[GitHub] [iceberg] rdblue commented on a diff in pull request #3432: Doc: add a page to explain row-level deletes
rdblue commented on code in PR #3432:
URL: https://github.com/apache/iceberg/pull/3432#discussion_r841285134
##########
site/docs/row-level-deletes.md:
##########
@@ -0,0 +1,190 @@
+<!--
+ - 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.
+ -->
+
+# Row-Level Deletes
+
+Iceberg supports metadata-based deletion through the `DeleteFiles` interface.
+It allows you to quickly delete a specific file or any file that might match a given expression without the need to read or write any data in the table.
+
+Row-level deletes target more complicated use cases such as general data protection regulation (GDPR).
+Copy-on-write and merge-on-read are two different approaches to handle row-level delete operations. Here are their definitions in Iceberg:
+
+- **copy-on-write**: a delete directly rewrites all the affected data files.
+- **merge-on-read**: delete information is encoded in the form of _delete files_. The table reader can apply all delete information at read time.
Review Comment:
It may just be me, but I strongly prefer the terms **eager** and **lazy** to describe these differences rather than copy-on-write or merge-on-read. Even if we clarify in the definitions here that we mean copy-on-write and merge-on-read, I think it would be better so that we can to the behavior with more descriptive terms.
For example:
> In the eager approach, given a user's delete requirement, the write process will search for all the affected data files and perform a rewrite operation.
I think that makes it really clear what is happening and why.
##########
site/docs/row-level-deletes.md:
##########
@@ -0,0 +1,190 @@
+<!--
+ - 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.
+ -->
+
+# Row-Level Deletes
+
+Iceberg supports metadata-based deletion through the `DeleteFiles` interface.
+It allows you to quickly delete a specific file or any file that might match a given expression without the need to read or write any data in the table.
+
+Row-level deletes target more complicated use cases such as general data protection regulation (GDPR).
+Copy-on-write and merge-on-read are two different approaches to handle row-level delete operations. Here are their definitions in Iceberg:
+
+- **copy-on-write**: a delete directly rewrites all the affected data files.
+- **merge-on-read**: delete information is encoded in the form of _delete files_. The table reader can apply all delete information at read time.
Review Comment:
It may just be me, but I strongly prefer the terms **eager** and **lazy** to describe these differences rather than copy-on-write or merge-on-read. Even if we clarify in the definitions here that we mean copy-on-write and merge-on-read, I think it would be better so that we can to the behavior with more descriptive terms.
For example:
> In the eager approach, given a user's delete requirement, the write process will search for all the affected data files and perform a rewrite operation.
I think that makes it really clear what is happening and why.
@aokolnychyi, what do you think?
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