diff --git a/src/main/resources/sql/fixtures/07-comment.sql b/src/main/resources/sql/fixtures/07-comment.sql
index 5b5f79c..930aad4 100644
--- a/src/main/resources/sql/fixtures/07-comment.sql
+++ b/src/main/resources/sql/fixtures/07-comment.sql
@@ -14,7 +14,7 @@ begin
     from (select *, row_number() over () % (article_count+7) rn from citizen, lateral generate_series(1, 5) g) z
     join (select *, row_number() over () rn from article) a using (rn);
 
-    insert into comment_on_article (id, created_by_id, target_id, content, parent_id)
+    insert into comment_on_article (id, created_by_id, target_id, content, parent_comment_id)
     select
         uuid_in(md5('comment_on_article_2'||row_number() over ())::cstring),
         z.id,
@@ -24,7 +24,7 @@ begin
     from (select *, row_number() over () % (article_count+7) rn from citizen, lateral generate_series(1, 5) g) z
     join (select *, row_number() over () rn from comment_on_article) a using (rn);
 
-    insert into comment_on_article (id, created_by_id, target_id, content, parent_id)
+    insert into comment_on_article (id, created_by_id, target_id, content, parent_comment_id)
     select
         uuid_in(md5('comment_on_article_3'||row_number() over ())::cstring),
         z.id,
@@ -32,7 +32,7 @@ begin
         'content' || row_number() over () * g,
         a.id
     from (select *, row_number() over () % (article_count+7) rn from citizen, lateral generate_series(1, 5) g) z
-    join (select *, row_number() over () rn from comment_on_article where parent_id is not null) a using (rn);
+    join (select *, row_number() over () rn from comment_on_article where parent_comment_id is not null) a using (rn);
 
     insert into comment_on_constitution (id, created_by_id, target_id, content)
     select
diff --git a/src/main/resources/sql/functions/comment/comment.sql b/src/main/resources/sql/functions/comment/comment.sql
index 8796484..57eb7cd 100644
--- a/src/main/resources/sql/functions/comment/comment.sql
+++ b/src/main/resources/sql/functions/comment/comment.sql
@@ -1,20 +1,20 @@
-create or replace function comment(reference regclass, target_id uuid, created_by_id uuid, content text, parent_id uuid default null, out id uuid)
+create or replace function comment(reference regclass, target_id uuid, created_by_id uuid, content text, parent_comment_id uuid default null, out id uuid)
     language plpgsql as
 $$
 declare
     _created_by_id alias for created_by_id;
     _target_id alias for target_id;
     _content alias for content;
-    _parent_id alias for parent_id;
+    _parent_comment_id alias for parent_comment_id;
     _id alias for id;
 begin
     if reference = 'article'::regclass then
-        insert into comment_on_article (created_by_id, target_id, content, parent_id)
-        values (_created_by_id, _target_id, _content, _parent_id)
+        insert into comment_on_article (created_by_id, target_id, content, parent_comment_id)
+        values (_created_by_id, _target_id, _content, _parent_comment_id)
         returning comment_on_article.id into _id;
     elseif reference = 'constitution'::regclass then
-        insert into comment_on_constitution (created_by_id, target_id, content, parent_id)
-        values (_created_by_id, _target_id, _content, _parent_id)
+        insert into comment_on_constitution (created_by_id, target_id, content, parent_comment_id)
+        values (_created_by_id, _target_id, _content, _parent_comment_id)
         returning comment_on_constitution.id into _id;
     else
         raise exception 'comment with target as "%", is no implemented', reference::text;
diff --git a/src/main/resources/sql/functions/comment/find_comments_by_parent.sql b/src/main/resources/sql/functions/comment/find_comments_by_parent.sql
index 4c1b25e..9edcdb4 100644
--- a/src/main/resources/sql/functions/comment/find_comments_by_parent.sql
+++ b/src/main/resources/sql/functions/comment/find_comments_by_parent.sql
@@ -15,7 +15,7 @@ begin
             find_reference_by_id(com.target_id, com.target_reference) as target,
             find_citizen_by_id(com.created_by_id) as created_by
         from "comment" as com
-        where com.parents_ids @> array[_parent_id]
+        where parent_id = _parent_id
         order by com.parents_ids nulls first, created_at desc,
         com.created_at desc
         limit "limit" offset "offset"
diff --git a/src/main/resources/sql/migrations/0000-init_schema.up.sql b/src/main/resources/sql/migrations/0000-init_schema.up.sql
index 271c3ea..0b0fc48 100644
--- a/src/main/resources/sql/migrations/0000-init_schema.up.sql
+++ b/src/main/resources/sql/migrations/0000-init_schema.up.sql
@@ -368,11 +368,12 @@ create table follow_citizen
 
 create table comment
 (
-    updated_at  timestamptz default now() not null check ( updated_at >= created_at ),
-    "content"   text                      not null check ( content != '' and length(content) < 4096),
-    parent_id   uuid references comment (id),
-    parents_ids uuid[],
-    deleted_at  timestamptz               null,
+    updated_at        timestamptz default now() not null check ( updated_at >= created_at ),
+    "content"         text                      not null check ( content != '' and length(content) < 4096),
+    parent_id         uuid                      not null,
+    parent_comment_id uuid references comment (id),
+    parents_ids       uuid[],
+    deleted_at        timestamptz               null,
     foreign key (created_by_id) references citizen (id),
     primary key (id)
 ) inherits (extra);
@@ -380,20 +381,25 @@ create table comment
 create index comment_parents_ids_idx
     on comment (parents_ids);
 
+create index parent_id
+    on comment (parent_id);
+
 create or replace function set_comment_parents_ids() returns trigger
     language plpgsql as
 $$
 begin
-    if (new.parent_id is not null) then
+    if (new.parent_comment_id is not null) then
         new.parents_ids = (
             select com.parents_ids || com.id
             from "comment" com
-            where com.id = new.parent_id
+            where com.id = new.parent_comment_id
         );
     else
-        new.parents_ids = null;
+        new.parents_ids = array [new.target_id]::uuid[];
     end if;
 
+    new.parent_id = (new.parents_ids[array_upper(new.parents_ids, 1)]);
+
     return new;
 end;
 $$;
@@ -409,7 +415,7 @@ create table comment_on_article
     target_reference regclass default 'article'::regclass not null,
     foreign key (created_by_id) references citizen (id),
     foreign key (target_id) references article (id),
-    foreign key (parent_id) references comment_on_article (id),
+    foreign key (parent_comment_id) references comment_on_article (id),
     primary key (id)
 ) inherits (comment);
 
@@ -427,7 +433,7 @@ create table comment_on_constitution
     target_reference regclass default 'constitution'::regclass not null,
     foreign key (created_by_id) references citizen (id),
     foreign key (target_id) references constitution (id),
-    foreign key (parent_id) references comment_on_constitution (id),
+    foreign key (parent_comment_id) references comment_on_constitution (id),
     primary key (id)
 ) inherits (comment);
 
diff --git a/src/test/sql/comment.sql b/src/test/sql/comment.sql
index bb5fd05..6630acc 100644
--- a/src/test/sql/comment.sql
+++ b/src/test/sql/comment.sql
@@ -93,7 +93,7 @@ begin
         target_id => (created_article->>'id')::uuid,
         created_by_id => _citizen_id,
         content => 'God not exist'::text,
-        parent_id => _comment_id::uuid
+        parent_comment_id => _comment_id::uuid
     ) into _comment_id_response;
 
     select "comment"(
@@ -101,7 +101,7 @@ begin
         target_id => (created_article->>'id')::uuid,
         created_by_id => _citizen_id,
         content => 'are you really sure ?'::text,
-        parent_id => _comment_id_response::uuid
+        parent_comment_id => _comment_id_response::uuid
     ) into _comment_id_response2;
     assert (select count(*) = 3 from "comment"), 'response must be inserted';
     assert (select com.parents_ids @> ARRAY[_comment_id] from "comment" com where id = _comment_id_response), 'parents_ids not contain "' || _comment_id::text || '" ' || (select com.parents_ids::text[] from "comment" com where id = _comment_id_response);