Memory allocation while using lookup stage

Hi friends, i know while using lookup stage if the lookup table has huge amount of data we will go for sparse lookup or else will use normal lookup.
would anybody explain how the memory will be allocated for both type of lookups?

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"Hi friends, i know while using lookup stage if the lookup table has huge amount of data we will go for sparse lookup or else will use normal lookup.
would anybody explain how the memory will be allocated for both type of lookups?"

 First of all, What you know is wrong.

" if the lookup table has huge amount of data we will go for sparse lookup"

 This assumption is completely wrong. The lookup type is not decided by the data on the reference link but by the amount of data on the input link.

If and only if your input link has few records, Then you can go for a Sparse Lookup. There is no memory allocation for this type of lookup, And a SQL where clause is directly fired on the reference link database for fetching the lookup key value.

In case of a Normal Lookup, The entire reference link data is read into the memory and then a lookup is done in the memory itself.

So memory comes into picture only for normal lookup's and not for Sparse lookup's.

This should clarify.......

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