Part one
What is Row-Level Security in Power BI?
Row-Level Security (RLS) controls which rows of data an
individual user can see when they open a report, based on who they are,
not which report they opened.
It is worth separating this from what it is not. RLS does not hide pages
or visuals. It does not stop someone opening a report. It works at the
data level: when a user views a report, Power BI applies a filter behind
the scenes so they only receive the data they are entitled to. Everyone
can use the same report; each person simply sees their own slice of it.
Imagine a single sales dashboard used across three regions: North,
South and West. Without RLS, protecting regional confidentiality
usually means building the same dashboard three times, one per
region. That is triple the build cost and triple the maintenance,
forever.
With RLS, you build it
once. A rule
maps each user to their region. The North manager opens the
dashboard and sees North. The South manager opens the same dashboard
and sees South. Neither can see the other's numbers, and there is
only one report to maintain.
Do you actually need it?
RLS is often discussed as though every organisation needs it
immediately. That is not quite right. The honest answer is: you need it
when you have a reason to restrict data by who someone is, and that
reason is meaningful enough to justify the design effort.
In practice, that is the case more often than not:
-
You share reporting across
departments, regions, business units or customer groups.
-
The reporting contains
commercially sensitive or personal data
that not every viewer should see in full.
-
You are currently
duplicating reports
to work around access concerns.
-
You are subject to
GDPR obligations
and need to demonstrate control over who accesses what.
If none of these apply and everyone can see everything legitimately, RLS
may simply be unnecessary complexity. Part of good governance is knowing
when not to add controls.
Where RLS actually pays for itself
The cost of RLS is upfront design work. The saving is that you
maintain one report instead of many. Once report duplication starts,
the maintenance cost compounds with every copy, so the case for RLS
usually strengthens over time, even if it looks like overhead at the
start.