Re^3: Reading HUGE file multiple times

I've tried $Library_Index{<$Library>} = tell(ARGV), scalar <$Library> until eof();but it takes very long time to do.

How long?

I wonder if there is a better way to do it since this would be a bottleneck.

If you are re-using the file many times you could construct the index and write it to a separate file. It should be substantially quicker to read the index from a file than to construct it from scratch each time.

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

Comment on Re^3: Reading HUGE file multiple times Download Code

Replies are listed 'Best First'.
Re^4: Reading HUGE file multiple times by Anonymous Monk on Apr 28, 2013 at 13:36 UTC
It's over 10 min so I kill the process. I think the reason is it's writing data line as a hash name and the data line can have 300.000 characters. I changed it so it only reads the index of the ID and then will just add 1 to it when I need the data. Then it's done in couple of seconds. Thanks for the tips with the index.	[reply]
Re^5: Reading HUGE file multiple times by BrowserUk (Patriarch) on Apr 28, 2013 at 13:45 UTC
I think the reason is it's writing data line as a hash name and the data line can have 300.000 characters. No, it's not. At least, if your description of the file is accurate it isn't. This bit of the code: `$Library_Index{<$Library>} = tell(ARGV),` reads the IDs and constructs the hash. And this bit: `scalar <$Library>` reads and discards the long data lines. However, Now I think I see the problem with your version of the code. This bit:`until eof();` of the line iterates until the file is read, except that you forgot to put the filehandle `$Library` in the parens, so the program will never end because it is testing the end-of-file condition of a different file which will never be true. Change the line to: `$Library_Index{<$Library>} = tell(ARGV), scalar <$Library> until eof($ +Library);` [download] And see how long it takes. With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice.	[reply] [d/l] [select]
Re^6: Reading HUGE file multiple times by Anonymous Monk on Apr 28, 2013 at 14:16 UTC
Ups, replied in a wrong place. I tried the new code and it works really fast. Problem is there is an error with tell and it's all -1. Would be nice if I could just have ENST04000413399 as and ID but it does not mater that much. From Dumper `$VAR32564 = -1; $VAR32565 = '>ENST04000413399 ';` [download]	[reply] [d/l]
Re^7: Reading HUGE file multiple times by BrowserUk (Patriarch) on Apr 28, 2013 at 14:42 UTC
Re^8: Reading HUGE file multiple times by Anonymous Monk on Apr 28, 2013 at 20:03 UTC
Re^4: Reading HUGE file multiple times by Anonymous Monk on Apr 28, 2013 at 14:06 UTC
I tried the new code and it works really fast. Problem is there is an error with tell and it's all -1. From Dumper `$VAR32564 = -1; $VAR32565 = '>ENST00400413799 ';` [download]	[reply] [d/l]