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I'm trying to optimize some queries because I'm working on tables with millions of records. I have a table with about 20 million records. Each row has a date (required), a user (required), and a value (not required). I am interested in consecutive dates in which the value remains above 100 for a user. So, if a user has 104, 78, 110, I'm not interested in any of the dates attached to those values. I only want the second date in which two dates have a value above 100 without a value below 100 (or null) between them. If the user has four dates in a row above 100, I want the last three because each pair is a pair of consecutive dates in which the value is above 100. With a couple million users and 20 million records, every query I've tried takes forever to run. Does anyone know of a trick to make this run in a matter of minutes as opposed to days? The query should return user and date for each date that a user has a consecutive value above 100. -- kainaw ™ 02:49, 29 March 2008 (UTC)
count | #users | #dates | #values |
---|---|---|---|
20000000 | 2000000 | 10 | 200 |
Why does "cannot remove folder:directory is not empty."appear when i try to delete a specific file from my thumbdrive? This problem does not seem to exist when I delete other files from the thumdrive. Also, the file is read-only. I tried to change the attribute to unset read-only but every time I open 'properties' again, it still remains read-only. The thumdrive is fine other then these problems. is there any software or do i have to run anything to solve this problem. By the way, the format of the thumbdrive is FAT32, 3.98GB. Please help. Invisiblebug590 ( talk) 05:41, 29 March 2008 (UTC)
I had exactly the same a similar problem just a few days ago. I went home, salvaged anything I could and then formatted the drive. Maybe you would want to look at
Clamwin Portable from
Portableapps.com for the virus detection in the future?
Kushal
14:58, 29 March 2008 (UTC)
I am trying to install windows vista (ultimate 64-bit OEM) on my new computer, and it is really not playing ball. It gets to varying stages of installation each time I try, the farthest has been the product key entering screen, it is always very slow during the process. It then either freezes, or blue-screens with a message 'PFN_LIST_CORRUPT'. Could anyone offer a solution? Englishnerd 12:23, 29 March 2008 (UTC)
Seriously.
Please try using memtest86+ to see if your RAM modules are working properly. Hope that helps. Kushal 14:13, 30 March 2008 (UTC)
... for 32-bit XP on AMD64 machine? -- 212.149.216.233 ( talk) 13:53, 29 March 2008 (UTC)
Why isn't Wikipedia in it's normal condition? Heegoop, 29 March 2008 (UTC)
Hello, I'm trying to track down teaching material for a CS undergraduate degree available online. I wondered if anyone knew of an institution (perhaps someone's alma mater) which has good stuff freely available. Thanks. 90.203.189.60 ( talk) 19:09, 29 March 2008 (UTC)
Me again - even reading lists would be good. Thanks. 90.203.189.60 ( talk) 19:10, 29 March 2008 (UTC)
Connexions at Rice university hosts a large collection of free educational material. I don't know if they have what you are looking for but it's worth a look. The website is at
http://cnx.org/.
Theresa Knott |
The otter sank
10:30, 30 March 2008 (UTC)
MIT Open course ware.
http://mitpress.mit.edu/sicp/full-text/book/book.html
and
http://ocw.mit.edu/OcwWeb/web/home/home/index.htmM
Also Philip Greenspun...
http://philip.greenspun.com/seia/
My computer has just decided that when I right click it will put up the menu transparent untill i run my mouse over the options. How can I get this back to normal as I find pretty darn annoying? —Preceding unsigned comment added by 79.64.12.133 ( talk) 23:25, 29 March 2008 (UTC)
I get this every once in a while and don't know how to sort it out. I can't even figure out what causes it but a reboot fixes it. Logging out might fix it too TheGreatZorko ( talk) 12:08, 2 April 2008 (UTC)
Computing desk | ||
---|---|---|
< March 28 | << Feb | March | Apr >> | March 30 > |
Welcome to the Wikipedia Computing Reference Desk Archives |
---|
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages. |
I'm trying to optimize some queries because I'm working on tables with millions of records. I have a table with about 20 million records. Each row has a date (required), a user (required), and a value (not required). I am interested in consecutive dates in which the value remains above 100 for a user. So, if a user has 104, 78, 110, I'm not interested in any of the dates attached to those values. I only want the second date in which two dates have a value above 100 without a value below 100 (or null) between them. If the user has four dates in a row above 100, I want the last three because each pair is a pair of consecutive dates in which the value is above 100. With a couple million users and 20 million records, every query I've tried takes forever to run. Does anyone know of a trick to make this run in a matter of minutes as opposed to days? The query should return user and date for each date that a user has a consecutive value above 100. -- kainaw ™ 02:49, 29 March 2008 (UTC)
count | #users | #dates | #values |
---|---|---|---|
20000000 | 2000000 | 10 | 200 |
Why does "cannot remove folder:directory is not empty."appear when i try to delete a specific file from my thumbdrive? This problem does not seem to exist when I delete other files from the thumdrive. Also, the file is read-only. I tried to change the attribute to unset read-only but every time I open 'properties' again, it still remains read-only. The thumdrive is fine other then these problems. is there any software or do i have to run anything to solve this problem. By the way, the format of the thumbdrive is FAT32, 3.98GB. Please help. Invisiblebug590 ( talk) 05:41, 29 March 2008 (UTC)
I had exactly the same a similar problem just a few days ago. I went home, salvaged anything I could and then formatted the drive. Maybe you would want to look at
Clamwin Portable from
Portableapps.com for the virus detection in the future?
Kushal
14:58, 29 March 2008 (UTC)
I am trying to install windows vista (ultimate 64-bit OEM) on my new computer, and it is really not playing ball. It gets to varying stages of installation each time I try, the farthest has been the product key entering screen, it is always very slow during the process. It then either freezes, or blue-screens with a message 'PFN_LIST_CORRUPT'. Could anyone offer a solution? Englishnerd 12:23, 29 March 2008 (UTC)
Seriously.
Please try using memtest86+ to see if your RAM modules are working properly. Hope that helps. Kushal 14:13, 30 March 2008 (UTC)
... for 32-bit XP on AMD64 machine? -- 212.149.216.233 ( talk) 13:53, 29 March 2008 (UTC)
Why isn't Wikipedia in it's normal condition? Heegoop, 29 March 2008 (UTC)
Hello, I'm trying to track down teaching material for a CS undergraduate degree available online. I wondered if anyone knew of an institution (perhaps someone's alma mater) which has good stuff freely available. Thanks. 90.203.189.60 ( talk) 19:09, 29 March 2008 (UTC)
Me again - even reading lists would be good. Thanks. 90.203.189.60 ( talk) 19:10, 29 March 2008 (UTC)
Connexions at Rice university hosts a large collection of free educational material. I don't know if they have what you are looking for but it's worth a look. The website is at
http://cnx.org/.
Theresa Knott |
The otter sank
10:30, 30 March 2008 (UTC)
MIT Open course ware.
http://mitpress.mit.edu/sicp/full-text/book/book.html
and
http://ocw.mit.edu/OcwWeb/web/home/home/index.htmM
Also Philip Greenspun...
http://philip.greenspun.com/seia/
My computer has just decided that when I right click it will put up the menu transparent untill i run my mouse over the options. How can I get this back to normal as I find pretty darn annoying? —Preceding unsigned comment added by 79.64.12.133 ( talk) 23:25, 29 March 2008 (UTC)
I get this every once in a while and don't know how to sort it out. I can't even figure out what causes it but a reboot fixes it. Logging out might fix it too TheGreatZorko ( talk) 12:08, 2 April 2008 (UTC)