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“INSERT IGNORE” vs “INSERT … ON DUPLICATE KEY UPDATE”
...ly, which has some unexpected side effects:
A new auto-increment ID is allocated.
Dependent rows with foreign keys may be deleted (if you use cascading foreign keys) or else prevent the REPLACE.
Triggers that fire on DELETE are executed unnecessarily.
Side effects are propagated to replicas too....
What are some better ways to avoid the do-while(0); hack in C++?
... r1, r2; // , ...;
if(error_ok != (result = computation1(&r1))) // Allocates local resources
goto cleanup;
if(error_ok != (result = computation2(&r2))) // Allocates local resources
goto cleanup;
// ...
// Commit code: all operations succeeded
*r = compute...
Sort Go map values by keys
... Benchmark1-8 2863149 374 ns/op 152 B/op 5 allocs/op
and this is what I would suggest using instead:
keys := make([]int, 0, len(myMap))
for k := range myMap {
keys = append(keys, k)
}
sort.Ints(keys)
// Benchmark2-8 5320446 230 ns/op 80...
What does the @ symbol represent in objective-c?
...tringWithUTF8String method." Well, not exactly. The strings are statically allocated, which makes them different from +[NSString stringWithUTF8String:] (those are dynamically allocated), and release and retain have no effect on them.
– user142019
Oct 31 '11 at ...
How do you load custom UITableViewCells from Xib files?
...m cell.
UIViewController *temporaryController = [[UIViewController alloc] initWithNibName:@"BDCustomCell" bundle:nil];
// Grab a pointer to the custom cell.
cell = (BDCustomCell *)temporaryController.view;
[[cell retain] autorelease];
// Release the temporary ...
Why does this code segfault on 64-bit architecture but work fine on 32-bit?
...o int* masks the fact that without the proper #include the return type of malloc is assumed to be int. IA-64 happens to have sizeof(int) < sizeof(int*) which makes this problem obvious.
(Note also that because of the undefined behaviour it could still fail even on a platform where sizeof(int)==...
How can I deploy an iPhone application from Xcode to a real iPhone device?
...w Run Script Build Phase. In the window, copy/paste this:
export CODESIGN_ALLOCATE=/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/codesign_allocate
if [ "${PLATFORM_NAME}" == "iphoneos" ]; then
/Developer/iphoneentitlements401/gen_entitlements.py "my.company.${PROJECT_NAME}" "${BUILT_PROD...
Fastest way to replace NAs in a large data.table
....805 12.301 134.985
system.time(a_andrie = f_andrie(dt1))
Error: cannot allocate vector of size 305.2 Mb
Timing stopped at: 14.541 7.764 68.285
system.time(f_dowle(dt1))
user system elapsed
7.452 4.144 19.590 # EDIT has faster than this
identical(a_gdata, dt1)
[1] TRUE
Note th...
Performance differences between debug and release builds
...s is a big one, it makes property accessors essentially free.
CPU register allocation. Local variables and method arguments can stay stored in a CPU register without ever (or less frequently) being stored back to the stack frame. This is a big one, notable for making debugging optimized code so di...
What's the difference between ASCII and Unicode?
...
ASCII has 128 code positions, allocated to graphic characters and control characters (control codes).
Unicode has 1,114,112 code positions. About 100,000 of them have currently been allocated to characters, and many code points have been made permanently...