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b7e29691c2
When we do a streaming read that knows the expected *end* position of the read, we can use a large read-ahead buffer, and at the same time, stop reading at exactly the intended end (or small rounding of it to the DMA block size) and not waste resources blindly reading a large amount of data after the end just to fill the read-ahead buffer. The sstable reading code, both for reading the data file and the index file, created a file input stream without specifiying its end, thereby losing this optimization - so when a large buffer was used, we would get a large over-read. This patch fixes this, so sstable data file and index file are read using a file input stream which is a ware of its end. Fixes #964. Note that this patch does not change the behavior when reading a *compressed* data file. For compressed read, we did not have the problem of over-read in the first place, because chunks are read one by one. But we do have other sources of inefficiencies there (stemming, again, from the fact that the compressed chunks are read one by one), and I opened a separate issue #992 for that. Signed-off-by: Nadav Har'El <nyh@scylladb.com> Message-Id: <1457219304-12680-1-git-send-email-nyh@scylladb.com>