• sourceNode represents the source node.
• targetNode represents the target node.
• For each attribute a
i
∈ ra
m
⊆ RA
M
it will be trans-
formed into a property p ← a
i
/P
R
= P
R
∪ p
• t
1
denotes the relationship type, t
1
= {dim − to −
dim}/T R = {t
1
}
5 CASE STUDY
This section presents the development of a person-
alized learning path recommendation system (LPRS)
based on career goals, showcasing our graph-based
NoSQL DW. We provide a practical example of ap-
plying the conceptual, logical, and physical design
phases for NoSQL DW to validate our conceptual
DW model and highlight graph databases’ strengths
in handling complex relationships and queries in rec-
ommendation systems.
Graph NoSQL databases outperform in com-
plex relationship modeling Fernandes and Bernardino
(2018); Sellami et al. (2019), making them ideal
for LPRS that analyze relationships between courses,
learning objectives (LO), and job positions. While
previous studies have focused on graph databases
Beutling and Spahic-Bogdanovic (2024); Nguyen
et al. (2022), we emphasize GDW’s scalable data in-
tegration and advanced analytics for personalized rec-
ommendations. Based on our previous Knowledge
Graph (KG) architecture Nguyen et al. (2022) links
educational resources with career objectives across
three layers: Career Concept, Course Concept, and
Competency Concept. We then create a GDW using
this KG to enhance data-driven recommendations for
LPRS.
The following subsections detail the next three
phases of NoSQL DW design, involving conceptual,
logical, and physical design.
5.1 Conceptual DW Model Design
In the conceptual DW model design process, we use
a top-down approach to identify essential data com-
ponents and their relationships, ensuring alignment
with problem requirements. For this case, we fo-
cus on addressing learning path recommendation is-
sues based on users’ existing skills and career goals.
We identify the main entity groups: Courses, Ca-
reers, Users, and Skills. Skills encompass various en-
tities such as Programming Languages, Frameworks,
Platforms, Knowledge Areas, and Tools, forming the
”Family Layer.” Within this layer, we define two types
of tables: ”Fact Family” and ”Dimension Family.”
The ”Fact Family” includes fact tables like job post-
ings and course enrollments, along with related mea-
sures. The ”Dimension Family” supports each fact
table with detailed data. For example, the job posting
fact table has dimensions like posting location, time,
career, website, and organization, while the course en-
rollment fact table includes course name, instructor,
website, and training organization.
We also identify optional attributes for dimen-
sions, such as skill requirements, proficiency levels
for courses, certifications for instructors, and phone
numbers for users, to optimize data querying and sup-
port advising. The complete conceptual DW model is
presented in Figure 2.
5.2 Mapping Logical DW Model Design
After designing the conceptual NoSQL DW model,
transitioning to a logical GDW model is crucial for
simplifying deployment and enhancing efficiency on
specific database types. This section outlines how to
map the conceptual NoSQL DW model to the logi-
cal GDW model using the mapping rules from sec-
tion 4. We’ll apply these rules to transform the LPRS
problem’s conceptual NoSQL DW model into a com-
plete logical GDW model, focusing on mapping en-
tities and relationships to corresponding components,
thereby streamlining deployment on graph databases.
The process involves two main steps:
Entity Mapping: Each entity identified in the
conceptual DW model, such as courses and websites,
is mapped to a separate node in the graph database.
The names and types of these entities are transformed
into corresponding labels, ensuring clear node identi-
fication. Attributes are also mapped to the properties
of corresponding nodes.
Relationship Conversion: The relationships be-
tween entities, depicted by crow’s foot symbols in the
conceptual DW model, are converted into edges con-
necting the corresponding nodes in the graph. This
step elucidates relationships, enabling a comprehen-
sive and interconnected representation of nodes in the
graph database. Figure 3 illustrates the logical graph
model after conversion.
5.3 Building LPRS Solution Based on
GDW
Based on the proposed logical GDW model, we de-
ployed it using the Neo4j platform, incorporating data
from 4,000 course records and 2,000 job postings
sourced from public job websites. In this GDW, data
entities are represented as nodes, and relationships are
effectively modeled.
A Comprehensive Approach for Graph Data Warehouse Design: A Case Study for Learning Path Recommendation Based on Career Goals
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