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[LDM #BIQ-359809]: LDM Redundant Request and PQACT question



Hi Mike,

re:
> Let's say I have two requests from the same feed but from two different
> hosts, one is ".*" and the other is "(.*)".  My understanding here is this
> will result in data from both requests getting into the product queue and
> bypass the normal Primary / Alternate behavior.

Your understanding is a little bit off.  These REQUESTs will result in
all products from each upstream being sent, but only one of each
product will actually be inserted into the local LDM queue.  The first one
to arrive will be inserted into the queue and the second one will be
rejected since its MD5 signature will match a product that is already
in the queue.  We refer to this behaviour as duplicate product detection
and rejection.

re:
> My question is if data from both requests are making it into the PQ, will a
> single PQACT entry for that data be acted on once or twice?

There will only be one copy of each product inserted into the LDM queue,
and, therefore, it will only be acted on once.

re:
> I'm thinking about doing this for several of my requests to give me some
> added redundancy, but I just want to make sure I don't double-up on
> triggering PQACTs before I give myself a bad headache.

In the great majority of cases, you won't have to worry about this.  The
case that could result in the same product being inserted into the queue
more than once is when the receipt latencies for one feed exceed the
product residency time of the local LDM queue.  In this case, the product
can be reinserted since the one that was previously inserted will no
longer exist in the local queue.  The easiest way to protect against this
sort of situation is to make the local LDM queue large enough that the
product residency time exceeds the latency of products received.

Cheers,

Tom
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Ticket Details
===================
Ticket ID: BIQ-359809
Department: Support LDM
Priority: Normal
Status: Closed
===================
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NOTE: All email exchanges with Unidata User Support are recorded in the Unidata inquiry tracking system and then made publicly available through the web. If you do not want to have your interactions made available in this way, you must let us know in each email you send to us.