Hi everyone,
Does any body tell me what is hash file, where do we use them and what is exact purpose of hash file in datastage?
Thanks in advance,
Balaram
Hash file
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Have you searched the forum? Search also for "hashed file", which is the more technically correct name.
In short, a hashed file is a kind of table in which the location of a record is determined by applying an algorithm to the primary key value, rather than performing a table scan or index scan. Key-based access is extremely fast, so they're ideal for key-based reference lookups.
To make these even faster, hashed files (up to a certain size anyway) can be cached in memory, so that access occurs at memory speed rather than disk speed.
In short, a hashed file is a kind of table in which the location of a record is determined by applying an algorithm to the primary key value, rather than performing a table scan or index scan. Key-based access is extremely fast, so they're ideal for key-based reference lookups.
To make these even faster, hashed files (up to a certain size anyway) can be cached in memory, so that access occurs at memory speed rather than disk speed.
IBM Software Services Group
Any contribution to this forum is my own opinion and does not necessarily reflect any position that IBM may hold.
Any contribution to this forum is my own opinion and does not necessarily reflect any position that IBM may hold.