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Design problem About application related with cached rows

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Hello,

I try to create an application for my dissertation that caches rows from an romote database. The application handles a cache database which is identical with the original. The only difference is that it does not have autogenerated fields and referential integrity is omitted.

I have designed a caching algorithm specific to the context of my applocation. However, I have a problem that I cannot solve it:

I want to send a query to the remote database and then store the result to the cache instance. The cache database might have rows that can be duplicate with some rows of the resultset retrieved from the query.

The easy solution is to insert all the rows of the resultset one by one after I check their existence at the cache table. However, this solution impose network latency to the network because useless data is moved on the net.

Do you know any efficient way to fetch the exception (the rows that dont exist at the cache instance) of rows from the remote database using sql queries?

I tried to use the following kind of query but the database returns an overflow message if the query string is too long.

SELECT * FROM Customers WHERE CustomerID NOT IN (01,02, 03, ...);


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