There is a limit on the VARCHAR size of about 800 characters, and I am uncertain how these are counted as we have UTF-8 encoding. 200 characters should be enough for identities.

niclash · niclash · commit 42bc67f2c2f3 · 2018-05-03T08:34:46.000+08:00
diff --git a/extensions/entitystore-sql/src/main/java/org/apache/polygene/entitystore/sql/SqlType.java b/extensions/entitystore-sql/src/main/java/org/apache/polygene/entitystore/sql/SqlType.java
@@ -181,7 +181,7 @@ private static DataType<String> varCharType( SQLDialect dialect, boolean referen
         {
             if( reference )
             {
-                return SQLDataType.VARCHAR.length(1000).nullable(false);
+                return SQLDataType.VARCHAR.length(200).nullable(false);
             }
             else
             {

Original file line number	Diff line number	Diff line change
`@@ -181,7 +181,7 @@ private static DataType<String> varCharType( SQLDialect dialect, boolean referen`
`181`	`181`	`{`
`182`	`182`	`if( reference )`
`183`	`183`	`{`
`184`		`- return SQLDataType.VARCHAR.length(1000).nullable(false);`
	`184`	`+ return SQLDataType.VARCHAR.length(200).nullable(false);`
`185`	`185`	`}`
`186`	`186`	`else`
`187`	`187`	`{`