Lookup TransformSQL Server Integration Services

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The Lookup transformation performs lookups by joining data in input columns with columns in a reference dataset.

The Lookup transformation supports the following database providers for the OLE DB connection manager:

SQL Server Oracle DB2

It performs the Equi-join between source and reference dataset

What does Lookup Transform do?

Equi-join between source or transformation input and reference dataset ◦ I.e at least one row should match between

source and referenced dataset  The transformation supports join columns with

any data type, except for DT_R4, DT_R8, DT_TEXT, DT_NTEXT, or DT_IMAGE

Lookup Transform is case sensitive

Properties of Lookup transform

Full cache mode Partial cache mode No cache mode

What are different cache modes in Lookup transform ?

Referenced data set is just queried once during pre execution phase

All the referenced dataset is loaded in to the memory before even loading the source data into the buffer

Fast, Less query’s to the reference dataset It takes quiet bit of time depending up on

the reference data set for package execution to begin

Full cache mode

Here lookup cache begin with empty when package execution begin, when a new row comes from source to lookup the transformation then query’s the reference dataset.

If matched, that row from the reference dataset is cached in memory for next time.

If not matched it will discard the row from memory or can saved in the miss cache buffer, by default row is dropped.

Partial cache mode

Size limit for partial cache can be set in the advanced tab of lookup transform

Once cache is fill, lookup transform drops the last referenced rows from the cache cache

Continued..

As the name implies, in this mode the lookup transform doesn't maintain a lookup cache but, it keeps the last match around, as the memory has already been allocated. this means that look up transform still query’s the database for every row.

No cache mode

Cache connection manager Oledb connection manager

Types of connection managers?