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Is it a good idea to index datetime field in mysql?
...ne table with 4 million records. Most of my queries use datetime clause to select data. Is it a good idea to index datetime fields in mysql database?
...
How can I use grep to show just filenames on Linux?
...andard:
-l
(The letter ell.) Write only the names of files containing selected
lines to standard output. Pathnames are written once per file searched.
If the standard input is searched, a pathname of (standard input) will
be written, in the POSIX locale. In other locales, standard i...
What does Redis do when it runs out of memory?
...s reached Redis will try to remove keys
# according to the eviction policy selected (see maxmemory-policy).
#
# If Redis can't remove keys according to the policy, or if the policy is
# set to 'noeviction', Redis will start to reply with errors to commands
# that would use more memory, like SET, LPU...
How To Create Table with Identity Column
...ues ('NULL','address2')
insert into teppp ( addresss) values ('address3')
select * from teppp
null string , address1
NULL,address2
NULL,address3
If you try inserting same values as below:
insert into teppp ( name,addresss) values ('','address4')
insert into teppp ( name,addresss) values ('NULL',...
C++ templates that accept only certain types
...that the compiler allows these, and then declare a variable my_template<char> z; and verify that it doesn't.
– j_random_hacker
Nov 16 '17 at 16:20
...
live output from subprocess command
...ptimization: If we are only using one pipe, or no pipe at
# all, using select() or threads is unnecessary.
if [self.stdin, self.stdout, self.stderr].count(None) >= 2:
But, alas, here we've made at least two, and maybe three, different pipes, so the count(None) returns either 1 or 0. We...
Android 4.3 Bluetooth Low Energy unstable
... I have a work around for being unable to unpair. 1) go to your bt menu, select unpair, remove the ble device from the area or depower it, select the ble device in the bt menu and it'll try to pair and fail, then reset bluetooth. Upon reset the device will be unpaired.
– Chr...
Thread pooling in C++11
...or <ctpl_stl.h> if ou do not have Boost library
int main (int argc, char *argv[]) {
ctpl::thread_pool p(2 /* two threads in the pool */);
int arr[4] = {0};
std::vector<std::future<void>> results(4);
for (int i = 0; i < 8; ++i) { // for 8 iterations,
for ...
autolayout - make height of view relative to half superview height
...lso need to setup bottom, left, and right constraints, like normal)
. Then select the constraint and navigate to the Attribute inspector:
Then you can adjust the multiplier. If you want it 50% of the super view leave it at 1, since it is aligned per the super's center. This is also a great way to...
Database design for audit logging
...n as the FK. You then pull the consolidated record by JOINing like this:
SELECT * FROM Page
JOIN PageContent ON CurrentRevision = Revision AND ID = PageID
There might be some errors up there...this is off the top of my head. It should give you an idea of an alternative pattern, though.
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