Improve guide about creation of migration scripts

diff --git a/sonar-server/src/main/webapp/WEB-INF/db/migrate/README.txt b/sonar-server/src/main/webapp/WEB-INF/db/migrate/README.txt
index 15688e3dade2c51fe8c5ff51727760bd002a033d..52ae0b9f36b36ca3ab60b5acc2d15cd0ebe00ea5 100644 (file)
--- a/sonar-server/src/main/webapp/WEB-INF/db/migrate/README.txt
+++ b/sonar-server/src/main/webapp/WEB-INF/db/migrate/README.txt
@@ -1 +1,5 @@
+Don't forget that index name limited to 30 characters in Oracle DB.
+
+Prefer to add nullable columns to avoid problems during migration.
+
 After adding migration script - don't forget to update sonar-core/src/main/java/org/sonar/jpa/entity/SchemaMigration.java