Searchable columns have several restrictions.
You cannot specify text, unitext, image, or Java rawobject or rawobject in row columns as searchable columns.
Columns included in the searchable columns clause cannot have null values.
To perform bitmap comparison using the where clause in the subscription, you must include any columns that use the rs_address datatype in the replication definition’s searchable columns clause.
The more searchable columns in the searchable columns list of a replication definition, the slower Replication Server processes subscriptions; that is, the fewer searchable columns, the more efficiently Replication Server evaluates rows against subscriptions for the table.