Document the deprecation of wcf1_tag_to_object.languageID (#128)

Resolves #127

Co-authored-by: Matthias Schmidt <gravatronics@live.com>

diff --git a/docs/migration/wsc53/php.md b/docs/migration/wsc53/php.md
index 98bb62d7d0d99ffb06f81e95fedbf40ae70a29d7..85cbf2cf8ef17b172502b2d1555b2996a70c992f 100644 (file)
--- a/docs/migration/wsc53/php.md
+++ b/docs/migration/wsc53/php.md
@@ -88,3 +88,13 @@ The internal SCSS compiler object being stored in the `$compiler` property was a
 As the removal of the `$compiler` property effectively broke compatibility within the `StyleCompiler` and as the `StyleCompiler` never was meant to be extended, it was marked final.
 
 See [WoltLab/WCF#3929](https://github.com/WoltLab/WCF/pull/3929) for details.
+
+## Tags
+
+Use of the `wcf1_tag_to_object.languageID` column is deprecated.
+The `languageID` column is redundant, because its value can be derived from the `tagID`.
+With WoltLab Suite 5.4, it will no longer be part of any indices, allowing more efficient index usage in the general case.
+
+If you need to filter the contents of `wcf1_tag_to_object` by language, you should perform an `INNER JOIN wcf1_tag tag ON tag.tagID = tag_to_object.tagID` and filter on `wcf1_tag.languageID`.
+
+See [WoltLab/WCF#3904](https://github.com/WoltLab/WCF/pull/3904) for details.