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Grepping a huge file (80GB) any way to speed it up?
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If you have a multicore CPU, I would really recommend GNU parallel. To grep a big file in parallel use:
< eightygigsfile.sql parallel --pipe grep -i -C 5 'db_pd.Clients'
Depending on your disks and CPUs it may be faster to read larger blocks:
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What are bitwise operators?
...ut bit on the bottom line. So the answer to the above expression is 4. The CPU has done (in this example) 8 separate "AND" operations in parallel, one for each column.
I mention this because I still remember having this "AHA!" moment when I learned about this many years ago.
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Fast way of finding lines in one file that are not in another?
...iently large that storing them both causes a memory problem, you can trade CPU for memory by storing only file1 and deleting matches along the way as file2 is read.
BEGIN { FS="" }
(NR==FNR) { # file1, index by lineno and string
ll1[FNR]=$0; ss1[$0]=FNR; nl1=FNR;
}
(NR!=FNR) { # file2
if ($0 ...
Staging Deleted files
...bash console, leading to unknown option `deleted)
– Félix Gagnon-Grenier
Feb 15 '16 at 19:05
3
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How do I create a unique constraint that also allows nulls?
...onal disk space.
Note that if you don't want an index, you can still save CPU by making the expression be precalculated to disk by adding the keyword PERSISTED to the end of the column expression definition.
In SQL Server 2008 and up, definitely use the filtered solution instead if you possibly ca...
Should I instantiate instance variables on declaration or in the constructor?
...ow it was him). Personal taste is personal taste; ultimately, neither the CPU nor the JRE care about syntactical style.
– Aquarelle
Sep 20 '13 at 22:38
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'POCO' definition
... for better understanding what a POCO looks like.
– Héctor Álvarez
Apr 18 '18 at 14:33
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How do I automatically update a timestamp in PostgreSQL
... Says so in the Postgres documentation of the types. Varchar has extra CPU cycles to check for the constraint, which doesn't happen on TEXT.
– Rahly
Jun 21 '17 at 15:50
3
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Extract a dplyr tbl column as a vector
...e actually need to extract the vectors.
– Antoine Lizée
Apr 19 '16 at 3:38
This was the only way I could get a column...
MySQL LIKE IN()?
...05. If more then 5 REGEX, arround 0.0012...
– David Bélanger
Nov 26 '11 at 5:24
11
I had an issu...