When you execute a write operation, Sybase IQ does not immediately write the data to disk. Instead, it writes it into a data cache, an area in memory where it stores pages from the database while they are in use. Reading from and writing to the cache reduces the number of number of times Sybase IQ must access the disk. It is an essential part of IQ's high performance.
Eventually, IQ must write dirty pages—that is, pages that have been updated—to the disk. Sybase IQ writes dirty pages to disk each time a transaction commits. This approach is a major benefit to IQ users, because it means that IQ does not need to log data insertions in the transaction log. By not logging the very large insertions that are typical with IQ, users gain tremendous savings in disk and performance cost.
