Re: Index advisor in Navigator - why is it asking for DESC sequence?

yes, I am surprised...
however, as I look deeper, and click "show statements" (most of these
statements are from our windows PHP (via ODBC) processes)... I do see
"DESC" on lots of those SQL's....
However, I ask around our PHP developers....
"we NEVER do that"
"I did that ONE TIME, long ago..."

I am doing a grep on our php code to see how prevalent this really is.



On 1/14/2015 2:54 PM, John Yeung wrote:

On Wed, Jan 14, 2015 at 3:05 PM, Vernon Hamberg
<vhamberg@xxxxxxxxxxxxxxx> wrote:

Strictly speaking, the optimizer can use an ASC key to return rows in
DESC
order pretty efficiently - just start at the end and go backwards. Like
SETGT and READPE using an ASCending key LF.

This is exactly why OP is asking why DESC is being called for. If
ascending and descending are close enough to equivalent, why prefer
DESC?

Also, from OP's apparent level of surprise, I would guess he either
doesn't have anything that explicitly asks for descending order, or he
has a mix of ascending and descending.

John Y.

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