Hi All,
In my work environment, our workis to run N number of SQL statements
continously.. Actually we are in testing environment. And for this we write 100 of SQL's and execute each one after another at Windows SQL prompt.
Some of the SQL's will be running for about 12 hrs also.
... (1 Reply)
Hi ,
I wanted to find delata between two huge ( 8 GB ) files . Say file_TDY and file_YDY : These files are sorted based on a key .
I am using a command :
1)bdiff file_TDY file_YDY > diff_file
2) grep ' ^< ' diff_file > TDY_delta
I wanted only the changed records and newly added... (2 Replies)
Hi,
I am trying to do a diff between two files using "diff" command.I dont need my output to be printed using extra symbols ">" and "<" as we usually see for the diff command. Even to excude these characters in each line of the output, my diff output has inturn many symbols ">" and "<".
... (1 Reply)
Hi,
I search a unix utility to diff two files, that takes as argument numerical precision as well. If two files are different only in numbers and the difference is less than precision then the result as they are the same.
The precision may be absolute (x1-x2) or relative (x2/x1). Also I need the... (1 Reply)
Hi,
I am new to shell scripting.
please help me to find out the solution.
I need a script where we need to read the text file(consists of all file names) and get the file names one by one
and append the date suffix for each file name as 'yyyymmdd' .
Then search each file if exists... (1 Reply)
Hi I want to compare two rows in unix
first value in row is 1.12 while value in other row is 000001.12.
if i do normal diff this will come as difference...is it any way to overcome this? (1 Reply)
Discussion started by: sanranad
1 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)