Connected Vs Unconnected Lookup in IICS

Connected Vs Unconnected Lookup in IICS (Simple Explanation + Examples) walkthrough

Have you ever wondered why your mapping in Informatica IICS needs a Lookup Transformation? Or why there are two types—Connected and Unconnected—and which one you should use?

If these questions sound familiar, you’re in the right place! to discuss Connected Vs Unconnected Lookup in IICS In this blog, we’ll explain both types and show you real-time examples, and share common fixes so you can design your mappings confidently.

By the end, you’ll know:

1. What Connected and Unconnected Lookups are
2. When to use each one
3. How they impact performance
4. Practical examples and troubleshooting tips

What is a Lookup Transformation in IICS?

A Lookup Transformation in Informatica IICS is used to fetch additional data from another source and add it to your main data flow. Think of it like checking a reference table to get extra details.

For example:
You have a Customer table with Customer_id and Name
You want to add the State Name from another table that has State_code and State_Name
A Lookup Transformation helps you join these two tables without writing complex SQL.

Why do we use it?

1. To enrich data by adding missing details.
2. To validate data against a reference table,
3. avoid hardcoding values in mappings.“

✅ Key Points for Beginners

1. Lookup works like a search in another dataset.
2. It can return one or more columns based on your configuration.
3. It supports connected and unconnected modes (we’ll explain next).

Connected Lookup in IICS

A Connected Lookup is directly linked to the data flow in your mapping. It means the lookup transformation is part of the pipeline and passes data to the next transformation.

✅ Now Lets deep dive into each feature with example data how Connected Behaves

Feature 1. Connected to the mapping pipeline (shown in below)

Feature 2. Can return multiple columns from the lookup table( Shown Below)

The image shows a lookup operation where data from two tables is combined based on a common key (State_Code). After the lookup, the target table includes original columns (Customer_ID, State_Code) plus additional columns from the lookup table (State_Name, Region).

Feature 3. Supports All Cache Types

Static Cache Example: Department table rarely changes → use static cache.
Dynamic Cache Example: Customer table updates during session → dynamic cache.
Persistent Cache Example: Large product table reused across mappings → persistent cache.

Unconnected Lookup in IICS

An Unconnected Lookup is a way to get data from another table only when you need it. It does not stay connected to the main data flow. Instead, you call it like a function whenever you want a single value.

Unlike a Connected Lookup, which continuously passes data through its ports, an Unconnected Lookup:

1. Does not have input/output ports connected to other transformations.
2. You call it only when you need it using a special syntax like :LKP.lookupFunction()
3. Returns only one column value (or a single expression result) for each call.
4. You can call it only for certain conditions, not for every row.
5. Good when you need just one piece of data without adding extra complexity.

✅ Example Scenario

You have:

Customer Table: Customer_id, State_code
State Table: State_Code, State_Name, Region

You want to fetch Region for each customer:

1. Create an Unconnected Lookup on the State table.
2. Configure it to return Region where State_Code matches.
3. Call it in an expression using :LKP function

Difference of Connected and Unconnected

Aspect	Connected Lookup	Unconnected Lookup
Definition	A lookup that is directly connected to the main data flow through input/output ports.	A lookup that is not connected to the main flow; called on demand using a function.
Features	– Part of the pipeline – Can return multiple columns – Processes all rows	– Works like a function call – Returns one value only – Called conditionally
Example	Customer table connected to State table to fetch State_Name and Region for every row.	Customer table uses :LKP.getRegion(State_Code) to fetch Region only when needed.
When to Use	– When you need many columns from lookup table – For all rows in data flow	– When you need one column only – For specific rows or conditional lookups
Advantages	– Easy to understand – Can return multiple columns – Good for full joins	Keeps mapping simple – Better performance for conditional lookups – Lightweight
Disadvantages	– Can slow down mapping if unnecessary columns are fetched – Always processes all rows	– Can return only one column – Harder to manage if many lookups are needed

https://iicszone.com/iics-lookup-condition-why-your-lookup-returns-null-or-multiple-rows