Re: Support Parallel Query Execution in Executor

Gregory,

On 4/9/06 2:04 PM, "Gregory Maxwell" <gmaxwell(at)gmail(dot)com> wrote:

> It increases Linux's maximum readahead from 128K to 1meg .. and it
> should be smart enough that you could crank it up further without too
> much risk of hurting performance elsewhere.

Interesting - we are now routinely using the "blockdev --setra" to set the
block device readahead and our common setting now is 16MB, so I will look at
how the behavior of this adaptive readahead affects normal query workload.

From the patch:

Normally, the kernel uses a stock readahead logic that is well
understood and well tuned. This option enables a much complex and
feature rich one. It is more aggressive and memory efficient in
doing readahead, and supports some less-common access patterns such
as reading backward and reading sparsely. However, due to the great
diversity of real world applications, it might not fit everyone.

- Luke