GIN index uses to find posts by tag

-remove hive_post_tags table -extend hive_posts for a column with an arrays of tags id -tags are added next after a post, not in paralles as it was previously -fix bug with not removing tags for a post whose author removed tags during edition

hive/db/schema.py

@@ -154,8 +154,8 @@ def build_metadata():
         sa.Index('hive_posts_updated_at_idx', sa.text('updated_at DESC')),
         sa.Index('hive_posts_payout_plus_pending_payout_id_idx', sa.text('(payout+pending_payout), id, is_paidout'), postgresql_where=sql_text("counter_deleted = 0 AND NOT is_paidout")),
         sa.Index('hive_posts_category_id_payout_plus_pending_payout_depth_idx', sa.text('category_id, (payout+pending_payout), depth'), postgresql_where=sql_text("NOT is_paidout AND counter_deleted = 0")),
-        sa.Index('hive_posts_tags_ids_idx', 'tags_ids', postgresql_using="gin")
-    )
+        sa.Index('hive_posts_tags_ids_idx', 'tags_ids', postgresql_using="gin", postgresql_ops={'tags_ids': 'gin__int_ops'})
+        )
 
     sa.Table(
         'hive_post_data', metadata,
@@ -448,6 +448,8 @@ def create_fk(db):
 def setup(db):
     """Creates all tables and seed data"""
 
+    sql = """SELECT * FROM pg_extension WHERE extname='intarray'"""
+    assert db.query_row( sql ), "The database requires created 'intarray' extension"
     # initialize schema
     build_metadata().create_all(db.engine())