大约有 44,000 项符合查询结果（耗时：0.0266秒） [XML]
mysql check collation of a table
...s utf8_general_ci vs utf8_unicode_ci. This can cause error messages like HY000, 1267, Illegal mix of collations (utf8_general_ci,IMPLICIT) and (utf8_unicode_ci,IMPLICIT) for operation '='... which is the message that brought me to this page.
– Dewi Morgan
Sep 2...
pandas: How do I split text in a column into multiple rows?
...lution:
time python -c "import pandas as pd;
df = pd.DataFrame(['a b c']*100000, columns=['col']);
print df['col'].apply(lambda x : pd.Series(x.split(' '))).head()"
... compared to this alternative:
time python -c "import pandas as pd;
from scipy import array, concatenate;
df = pd.DataFrame(['a ...
Is the size of C “int” 2 bytes or 4 bytes?
... another bit|byte? Imagine, I can hold 3 digits (0 or 1), so I can go from 000 to 111 (which is decimal 7). 7 is right before an exponent of 2. If I could go until 8 (1000) then I could use those 4 digits all the way up to 15! Such as 32767 is right before an exponent of 2, exhausting all the bits|b...
The definitive guide to form-based website authentication [closed]
...er makes causes multiple repetitions of the hash algorithm, for example 10,000 times, which causes the attacker to guess the password 10,000 times slower.
Session data - "You are logged in as Spiderman69"
Once the server has verified the login and password against your user database and found a matc...
MySQL maximum memory usage
... my.ini
table_definition_cache = 400
that reduced memory usage from 400,000+ kb down to 105,000kb
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How to read a large file - line by line?
...dd it last, not first. First show the proper way.
– m000
Sep 20 '13 at 22:03
7
@katrielalex revis...
What is the difference between CMD and ENTRYPOINT in a Dockerfile?
...ceived, 0% packet loss
round-trip min/avg/max/stddev = 0.088/0.091/0.096/0.000 ms
Now, running the image with an argument will ping the argument:
$ docker run -it test google.com
PING google.com (173.194.45.70): 48 data bytes
56 bytes from 173.194.45.70: icmp_seq=0 ttl=55 time=32.583 ms
56 bytes ...
Threads vs Processes in Linux
...
Yes, I do have some data. I ran a test that creates 100,000 processes and a test that creates 100,000 threads. The thread version ran about 9x faster (17.38 seconds for processes, 1.93 for threads). Now this does only test creation time, but for short-lived tasks, creation time c...
How do I implement basic “Long Polling”?
...
<style type="text/css" media="screen">
body{ background:#000;color:#fff;font-size:.9em; }
.msg{ background:#aaa;padding:.2em; border-bottom:1px #000 solid}
.old{ background-color:#246499;}
.new{ background-color:#3B9957;}
.error{ background-color:#992E36;}
...
Why not use Double or Float to represent currency?
... do
you have left?
System.out.println(1.03 - .42);
prints out 0.6100000000000001.
The right way to solve this problem is
to use BigDecimal, int or long
for monetary calculations.
Though BigDecimal has some caveats (please see currently accepted answer).
...