01-07-2013
I don't think there is a super-fast way to handle 50G of data.
Taking advantage of a database index sounds as good a way as any, a proper DB is designed to duplicate-check data larger than memory.
10 More Discussions You Might Find Interesting
1. UNIX for Dummies Questions & Answers
i have a file with some 1000 entries it will contain entries like
1000,ram
2000,pankaj
1001,rahim
1000,ram
2532,govind
2000,pankaj
3000,venkat
2532,govind
what i want is i want to extract only the distinct rows from this file
so my output should contain only
1000,ram... (2 Replies)
Discussion started by: trichyselva
2 Replies
2. UNIX for Dummies Questions & Answers
hey all,
I need some help.
I have a text file with names in it.
My target is that if a particular pattern exists in that file more than once..then i want to rename all the occurences of that pattern by alternate patterns..
for e.g if i have PATTERN occuring 5 times then i want to... (3 Replies)
Discussion started by: ashisharora
3 Replies
3. Shell Programming and Scripting
I have a log file with posts looking like this:
--
Messages can be delivered by different systems at different times. The id number is used to sort out duplicate messages. What I need is to strip the arrival time from each post, sort posts by id number, and reattach arrival time to respective... (2 Replies)
Discussion started by: Ilja
2 Replies
4. Shell Programming and Scripting
Hi Experts,
Please check the following new requirement. I got data like the following in a file.
FILE_HEADER
01cbbfde7898410| 3477945| home| 1
01cbc275d2c122| 3478234| WORK| 1
01cbbe4362743da| 3496386| Rich Spare| 1
01cbc275d2c122| 3478234| WORK| 1
This is pipe separated file with... (3 Replies)
Discussion started by: tinufarid
3 Replies
5. Shell Programming and Scripting
Hi,
I have a file that I want to change the format of. It is a large file in rows but I want it to be comma separated (comma then a space).
The current file looks like this:
HI, Joe, Bob, Jack, Jack
After I would want to remove any duplicates so it would look like this:
HI, Joe,... (2 Replies)
Discussion started by: kylle345
2 Replies
6. HP-UX
I have 2 files; one file (say, details.txt) contains the details of employees and another file (say, emp.txt) has some selected employee names. I am extracting employee details from details.txt by using emp.txt and the corresponding code is:
while read line
do
emp_name=`echo $line`
grep -e... (7 Replies)
Discussion started by: arb_1984
7 Replies
7. UNIX for Dummies Questions & Answers
Hi All,
I am merging files coming from 2 different systems ,while doing that I am getting duplicates entries in the merged file
I,01,000131,764,2,4.00
I,01,000131,765,2,4.00
I,01,000131,772,2,4.00
I,01,000131,773,2,4.00
I,01,000168,762,2,2.00
I,01,000168,763,2,2.00... (5 Replies)
Discussion started by: Sri3001
5 Replies
8. Shell Programming and Scripting
i hav two files like
i want to remove/delete all the duplicate lines in file2 which are viz unix,unix2,unix3 (2 Replies)
Discussion started by: sagar_1986
2 Replies
9. Shell Programming and Scripting
i hav two files like
i want to remove/delete all the duplicate lines in file2 which are viz unix,unix2,unix3.I have tried previous post also,but in that complete line must be similar.In this case i have to verify first column only regardless what is the content in succeeding columns. (3 Replies)
Discussion started by: sagar_1986
3 Replies
10. Shell Programming and Scripting
I am trying to remove whitespaces from a file containing sample data as:
457 <EOFD> Mar 1 2007 12:00:00:000AM <EOFD> Mar 31 2007 12:00:00:000AM <EOFD> system <EORD> 458 <EOFD> Mar 1 2007 12:00:00:000AM<EOFD>agf <EOFD> Apr 20 2007 9:10:56:036PM <EOFD> prodiws<EORD> . Basically these... (11 Replies)
Discussion started by: amvip
11 Replies
LEARN ABOUT DEBIAN
bup-margin
bup-margin(1) General Commands Manual bup-margin(1)
NAME
bup-margin - figure out your deduplication safety margin
SYNOPSIS
bup margin [options...]
DESCRIPTION
bup margin iterates through all objects in your bup repository, calculating the largest number of prefix bits shared between any two
entries. This number, n, identifies the longest subset of SHA-1 you could use and still encounter a collision between your object ids.
For example, one system that was tested had a collection of 11 million objects (70 GB), and bup margin returned 45. That means a 46-bit
hash would be sufficient to avoid all collisions among that set of objects; each object in that repository could be uniquely identified by
its first 46 bits.
The number of bits needed seems to increase by about 1 or 2 for every doubling of the number of objects. Since SHA-1 hashes have 160 bits,
that leaves 115 bits of margin. Of course, because SHA-1 hashes are essentially random, it's theoretically possible to use many more bits
with far fewer objects.
If you're paranoid about the possibility of SHA-1 collisions, you can monitor your repository by running bup margin occasionally to see if
you're getting dangerously close to 160 bits.
OPTIONS
--predict
Guess the offset into each index file where a particular object will appear, and report the maximum deviation of the correct answer
from the guess. This is potentially useful for tuning an interpolation search algorithm.
--ignore-midx
don't use .midx files, use only .idx files. This is only really useful when used with --predict.
EXAMPLE
$ bup margin
Reading indexes: 100.00% (1612581/1612581), done.
40
40 matching prefix bits
1.94 bits per doubling
120 bits (61.86 doublings) remaining
4.19338e+18 times larger is possible
Everyone on earth could have 625878182 data sets
like yours, all in one repository, and we would
expect 1 object collision.
$ bup margin --predict
PackIdxList: using 1 index.
Reading indexes: 100.00% (1612581/1612581), done.
915 of 1612581 (0.057%)
SEE ALSO
bup-midx(1), bup-save(1)
BUP
Part of the bup(1) suite.
AUTHORS
Avery Pennarun <apenwarr@gmail.com>.
Bup unknown- bup-margin(1)