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In my attribute table for a shapefile, I am converting one field (Julian day) to another field (date) using the field calculator but I'm working with about 7.7 million rows. QGIS has been running for about 17 hours and is half way done. Is there a way to speed up this process? I have QGIS 2.14.19 Essen, not sure if upgrading to 2.18 would be faster.

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    Are you using a Linux-enabled toaster oven with a 60hz CPU? Is your data file on network-shared thumb drive? There's no way an update on a shapefile attribute should take more than 20-30 minutes, but there's no way to tell what's wrong with your process without being given details of the platform and data storage. – Vince Oct 15 '17 at 16:40
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    What does "directly on my network" mean? – underdark Oct 15 '17 at 19:21
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    Yes, by not having to open the attribute table it reduces burden on QGIS to refresh the table toward the end of the process. (sorry for this tardy reply btw.) – Kazuhito Oct 15 '17 at 23:04
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    aaah, please see the answer provided by @ndawson. – Kazuhito Oct 16 '17 at 0:31
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    So I tried it through layer properties and creating the new field went quickly but now I'm having problems saving the changes. I've left the program open for >1 hr and now QGIS isn't responding... – racheldeep Oct 16 '17 at 3:28
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Don't do it through the attribute table, or with any attribute tables open. Instead create new attributes directly though layer properties or via the field calculator from the main window.

Adding/deleting columns with attribute tables open is super-slow.

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    So I tried it through layer properties and creating the new field went quickly but now it's taking a very long time to save (an hour and counting) – racheldeep Oct 16 '17 at 1:41
  • Are you sure you didn't have any open attribute tables (maybe hidden behind the main window) when you added the attribute/saved? – ndawson Oct 16 '17 at 5:09
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    I'm positive. Everything runs smoothly until I turn off editing mode and save my new field – racheldeep Oct 16 '17 at 14:02
  • OK, so it wasn't working on QGIS 2.18 but it worked on QGIS 2.14! – racheldeep Oct 16 '17 at 15:31

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