[GitHub] [iceberg] emkornfield commented on a diff in pull request #7504: docs: Clarify some view issues

["emkornfield (via GitHub)" <gi...@apache.org>]

emkornfield commented on code in PR #7504:
URL: https://github.com/apache/iceberg/pull/7504#discussion_r1184094948


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format/view-spec.md:
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@@ -111,12 +111,13 @@ The SQL representation stores the view definition as a SQL SELECT, with metadata
 |-------------|---------------------|----------------|-------------|
 | _required_  | `type`              | `string`       | Must be `sql` |
 | _required_  | `sql`               | `string`       | A SQL SELECT statement |
-| _required_  | `dialect`           | `string`       | The dialect of the `sql` SELECT statement (e.g., "trino" or "spark") |
+| _required_  | `dialect`           | `string`       | The dialect of the `sql` SELECT statement (e.g., "trino" or "spark"). Unless a version is provided only one view definition for each `type` and `dialect` should be present in a view definition.  |

Review Comment:
   SQL is generally compatible across versions but not always.  For example from the Athena [engine versioning docs](https://docs.aws.amazon.com/athena/latest/ug/engine-versions.html):
   
   > When you start using a new engine version, a small subset of queries may break due to incompatibilities. You can use workgroups to test your queries in advance of the upgrade by creating a test workgroup that uses the new engine or by test upgrading an existing workgroup. For more information, see [Testing queries in advance of an engine version upgrade](https://docs.aws.amazon.com/athena/latest/ug/engine-versions-changing.html#engine-versions-testing).



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