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mongodb group values by multiple fields
... $slice just off the basic aggregation result. For "large" results, run parallel queries instead for each grouping ( a demonstration listing is at the end of the answer ), or wait for SERVER-9377 to resolve, which would allow a "limit" to the number of items to $push to an array.
db.books.aggregate(...
What is Java String interning?
...p://docs.oracle.com/javase/7/docs/api/java/lang/String.html#intern()
Basically doing String.intern() on a series of strings will ensure that all strings having same contents share same memory. So if you have list of names where 'john' appears 1000 times, by interning you ensure only one 'john' is a...
Why is there no xrange function in Python3?
...Some performance measurements, using timeit instead of trying to do it manually with time.
First, Apple 2.7.2 64-bit:
In [37]: %timeit collections.deque((x for x in xrange(10000000) if x%4 == 0), maxlen=0)
1 loops, best of 3: 1.05 s per loop
Now, python.org 3.3.0 64-bit:
In [83]: %timeit collec...
Ruby replace string with captured regex pattern
...d answer first without reading the entirety of answers. That seems to generally be the most efficient means of fixing a problem. Give Vicky a break! :)
– Josh M.
Jan 31 '14 at 3:43
...
Is inline assembly language slower than native C++ code?
...
Yes, most times.
First of all you start from wrong assumption that a low-level language (assembly in this case) will always produce faster code than high-level language (C++ and C in this case). It's not true. Is C code always faster than Java code? N...
获取文件系统映像及恢复删除的数据（FAT文件系统格式描述） - C/C++ - 清泛...
...iGetClassDevs(&CLSID_DeviceInstance, NULL, NULL, DIGCF_PRESENT); //getting all devices with a removable disk guid
if ( INVALID_HANDLE_VALUE == hDevInfo )
{
return devInfos;//exit if there are no devices
}
try
{
st...
获取文件系统映像及恢复删除的数据（FAT文件系统格式描述） - C/C++ - 清泛...
...iGetClassDevs(&CLSID_DeviceInstance, NULL, NULL, DIGCF_PRESENT); //getting all devices with a removable disk guid
if ( INVALID_HANDLE_VALUE == hDevInfo )
{
return devInfos;//exit if there are no devices
}
try
{
st...
获取文件系统映像及恢复删除的数据（FAT文件系统格式描述） - C/C++ - 清泛...
...iGetClassDevs(&CLSID_DeviceInstance, NULL, NULL, DIGCF_PRESENT); //getting all devices with a removable disk guid
if ( INVALID_HANDLE_VALUE == hDevInfo )
{
return devInfos;//exit if there are no devices
}
try
{
st...
获取文件系统映像及恢复删除的数据（FAT文件系统格式描述） - C/C++ - 清泛...
...iGetClassDevs(&CLSID_DeviceInstance, NULL, NULL, DIGCF_PRESENT); //getting all devices with a removable disk guid
if ( INVALID_HANDLE_VALUE == hDevInfo )
{
return devInfos;//exit if there are no devices
}
try
{
st...
获取文件系统映像及恢复删除的数据（FAT文件系统格式描述） - C/C++ - 清泛...
...iGetClassDevs(&CLSID_DeviceInstance, NULL, NULL, DIGCF_PRESENT); //getting all devices with a removable disk guid
if ( INVALID_HANDLE_VALUE == hDevInfo )
{
return devInfos;//exit if there are no devices
}
try
{
st...