> Institution: National Weather Service > Package Version: 6.4.4 > Operating System: RHEL WS Ver. 4u2 > Hardware Information: Dual Xeon 3.0GHZ with 3GB DDR > Inquiry: I am attempting to ldm a series of images to multiple sites (GIF). > My image sizes vary 1KB to 35KB and I receive the following error from some > of the smaller gif images (Seems to be an MD5 Sum Error) > > pqinsert ERROR: Product already in queue: 8a9f53fd4c568dcda50a353adf929f84 > 1798 20060202191503.218 EXP 000 > /data2/www/html/ridge/Warnings/Long/FWS/FWS_20060202_1805_Long_Warnings.gif > > I get this error even though the files are physically different. The files might be physically different, but the data they contain are identical. This is why the product-queue is rejecting the insertion. pqinsert(1) computes an MD5 checksum for the data-portion of every data-product. If two data-products have the same MD5 checksum, then the odds of them having different data is about 1:2^128, against. If the data-products are distinct, then they should have different MD5 checksums. For example, you could add a timestamp to the data to indicate when it was observed. A simple counter or filename would also suffice -- anything that would make the data different. Having different product-identifiers (i.e., filename) isn't enough because product-identifiers are used by the LDM system but not, in general, by decoders of the data. They must be able to recognize data-products from the data itself and not rely on the product-identifier. > Is there a way to force pqinsert to create a new value so that the image can > be sent through the ldm stream. If I purge the queue and send this file > first it works, but when I send the next file it says it is already in the > queueu. You could run pqexpire(1) on the queue, but that really won't help because the the downstream LDM will also reject data-products that have identical MD5 checksums. > Thank you for your time, > Paul Kirkwood Regards, Steve Emmerson Ticket Details =================== Ticket ID: UEF-429372 Department: Support LDM Priority: Normal Status: Closed
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