diff --git a/modules/comment/comment.class.php b/modules/comment/comment.class.php
index e6e25bab0..dc0b20777 100644
--- a/modules/comment/comment.class.php
+++ b/modules/comment/comment.class.php
@@ -108,6 +108,12 @@ class comment extends ModuleObject
 			return true;
 		}
 
+		// 2017.12.21 Add an index for nick_name
+		if(!$oDB->isIndexExists('comments', 'idx_nick_name'))
+		{
+			return true;
+		}
+		
 		return FALSE;
 	}
 
@@ -192,6 +198,12 @@ class comment extends ModuleObject
 		{
 			$oDB->addIndex('comments', 'idx_parent_srl', array('parent_srl'));
 		}
+		
+		// 2017.12.21 Add an index for nick_name
+		if(!$oDB->isIndexExists('comments', 'idx_nick_name'))
+		{
+			$oDB->addIndex('comments', 'idx_nick_name', array('nick_name'));
+		}
 	}
 
 	/**
diff --git a/modules/comment/schemas/comments.xml b/modules/comment/schemas/comments.xml
index cf9a31f02..6c6a6f34a 100644
--- a/modules/comment/schemas/comments.xml
+++ b/modules/comment/schemas/comments.xml
@@ -11,7 +11,7 @@
     <column name="password" type="varchar" size="60" />
     <column name="user_id" type="varchar" size="80" />
     <column name="user_name" type="varchar" size="80" notnull="notnull" />
-    <column name="nick_name" type="varchar" size="80" notnull="notnull" />
+    <column name="nick_name" type="varchar" size="80" notnull="notnull" index="idx_nick_name" />
     <column name="member_srl" type="number" size="11" notnull="notnull" index="idx_member_srl" />
     <column name="email_address" type="varchar" size="250" notnull="notnull" />
     <column name="homepage" type="varchar" size="250" notnull="notnull" />
diff --git a/modules/document/document.class.php b/modules/document/document.class.php
index 43cd110f6..130a20693 100644
--- a/modules/document/document.class.php
+++ b/modules/document/document.class.php
@@ -126,6 +126,9 @@ class document extends ModuleObject
 
 		// 2016. 3. 14 Add a column(document_upate_log) for admin
 		if(!$oDB->isColumnExists('document_update_log', 'is_admin')) return true;
+		
+		// 2017.12.21 Add an index for nick_name
+		if(!$oDB->isIndexExists('documents', 'idx_nick_name')) return true;
 
 		return false;
 	}
@@ -339,6 +342,12 @@ class document extends ModuleObject
 			$oDB->addColumn('document_update_log', 'is_admin', 'varchar', 1);
 			$oDB->addIndex('document_update_log', 'idx_is_admin', array('is_admin'));
 		}
+		
+		// 2017.12.21 Add an index for nick_name
+		if(!$oDB->isIndexExists('documents', 'idx_nick_name'))
+		{
+			$oDB->addIndex('documents', 'idx_nick_name', array('nick_name'));
+		}
 	}
 
 	/**
diff --git a/modules/document/schemas/documents.xml b/modules/document/schemas/documents.xml
index 1f45a3a7d..b53452ec9 100644
--- a/modules/document/schemas/documents.xml
+++ b/modules/document/schemas/documents.xml
@@ -17,7 +17,7 @@
     <column name="password" type="varchar" size="60" />
     <column name="user_id" type="varchar" size="80" />
     <column name="user_name" type="varchar" size="80" notnull="notnull" />
-    <column name="nick_name" type="varchar" size="80" notnull="notnull" />
+    <column name="nick_name" type="varchar" size="80" notnull="notnull" index="idx_nick_name" />
     <column name="member_srl" type="number" size="11" notnull="notnull" index="idx_member_srl" />
     <column name="email_address" type="varchar" size="250" notnull="notnull" />
     <column name="homepage" type="varchar" size="250" notnull="notnull" />