[392-search-of-reservations-by-hostname] Addressed some comments

doc/sphinx/arm/admin.rst

@@ -321,6 +321,25 @@ earlier version. To perform an upgrade, issue the following command:
 
    $ kea-admin db-upgrade mysql -u database-user -p database-password -n database-name
 
+.. note::
+
+    To search host reservations by hostname it is critical the collation of
+    the hostname column in the host table to be case-insensitive. Fortunately
+    the default collation in MySQL is case-insensitive. You can verify this
+    on your MySQL installation by:
+
+    .. code-block:: mysql
+
+      mysql> SELECT COLLATION('');
+      +-----------------+
+      | COLLATION('')   |
+      +-----------------+
+      | utf8_general_ci |
+      +-----------------+
+
+    According to the naming of collations when the name finishes by ``_ci``
+    the collation is case-insensitive.
+
 .. _pgsql-database:
 
 PostgreSQL

src/lib/dhcpsrv/base_host_data_source.h

@@ -141,6 +141,10 @@ public:
     /// This method returns all @c Host objects which represent reservations
     /// using a specified hostname.
     ///
+    /// @note: as hostnames are case-insensitive the search key is given
+    /// in lower cases, search indexes should either be case-insensitive
+    /// or be case-sensitive using the lower case version of hostnames.
+    ///
     /// @param hostname The lower case hostname.
     ///
     /// @return Collection of const @c Host objects.

src/lib/dhcpsrv/cql_host_data_source.h

@@ -198,6 +198,8 @@ public:
     /// This method returns all @c Host objects which represent reservations
     /// using a specified hostname.
     ///
+    /// Cassandra uses the new indexed lower_case_hostname column.
+    ///
     /// @param hostname The lower case hostname.
     ///
     /// @return Collection of const @c Host objects.

src/lib/dhcpsrv/host_container.h

@@ -91,6 +91,7 @@ typedef boost::multi_index_container<
         >,
 
         // Sixth index is used to search for the host using hostname
+        // (case-sensitive compare so the key is in lower case).
         boost::multi_index::ordered_non_unique<
             // Index using values returned by the @c Host::getLowerHostname
             boost::multi_index::const_mem_fun<Host, std::string,

src/lib/dhcpsrv/mysql_host_data_source.h

@@ -158,6 +158,8 @@ public:
     /// This method returns all @c Host objects which represent reservations
     /// using a specified hostname.
     ///
+    /// MySQL uses the case-insensitive hosts_by_hostname index on hostname.
+    ///
     /// @param hostname The lower case hostname.
     ///
     /// @return Collection of const @c Host objects.

src/lib/dhcpsrv/pgsql_host_data_source.h

@@ -187,6 +187,8 @@ public:
     /// This method returns all @c Host objects which represent reservations
     /// using a specified hostname.
     ///
+    /// PostgreSQL uses the hosts_by_hostname index on LOWER(hostname).
+    ///
     /// @param hostname The lower case hostname.
     ///
     /// @return Collection of const @c Host objects.