ODBC iterate table without storing in memory

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ODBC iterate table without storing in memory

Hi,

I need to have a way to iterate through a database table without actually storing it in memory anywhere. I want to essentially read through the rows like an input iterator.

I've tried using cursors with a select statement (select * from table_name), but this retrieves the entire table and feeds it back to be one row at a time. So this solution is no good. Instead, I need it to only feed me each row as I ask for it.

Any suggestions are greatly appreciated.

Thanks!

You'll just want to use a forward only cursor. Your DB will need to support this. For detials, see MSDN's How to: Use Cursors.

If you're using SQL Server, you can use a Fast Forward-Only Cursor, which provides extra benefits.

Reed Copsey 2009-12-09 23:19:16

Thank you for your help. However I have already looked into Cursors and they are not what I'm looking for. They save the data before iterating through it. Thus it takes a long time with a large database to execute a 'select' query. I want to just be able fetch the data row by row without having it load into memory first. I want to read it straight from the database to ensure it is fast. Right now it is very slow and sometimes crashes if the database is too large

bumper 2009-12-15 20:36:03

Forward only cursors don't "save the data" before iterating through it - they save a small cache of a few records, but automatically delete it as you move. THere is no way (in ODBC) to directly load row-by-row. You'll need to use native API for your DB if you want to do that. Forward only cursors (and FF-Only for SQL Server) are the "lightweight" way of accessing data in ODBC.

Reed Copsey 2009-12-16 16:39:52

ansaurus

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ODBC iterate table without storing in memory

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