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There are some options that are very useful while working with the Lookup Transform; using them will help use the Lookup Transform to its full potential with improved performance in most situations. The next two options reveal these advanced properties.
Cache mode
As Lookup Transform looks for every record from source input inside the reference table, there should be performance tweaks to use during this lookup. SSIS provides a way to use the Cache option and cache the lookup table.
There are three options in the General tab of the Lookup Transform Editor's Cache mode setting:
Full Cache: The lookup table will be fully loaded in the cache memory.
This option will be optimal if the lookup table is not very large.
Partial Cache: The lookup table will be loaded in cache memory, but not fully.
When you select this option, the size of cache can be defined in the Advanced tab with the Cache Size option.
No Cache: The lookup table doesn't cache in memory.
Connection type
The Lookup Transform...
