大约有 40,000 项符合查询结果（耗时：0.0274秒） [XML]
Timer function to provide time in nano seconds using C++
... <chrono>. Additionally I'll demonstrate how you can templatize the testing code on the clock so that you can rapidly switch between RDTSC and your system's built-in clock facilities (which will likely be based on clock(), clock_gettime() and/or QueryPerformanceCounter.
Note that the RDTSC i...
Throw an error in a MySQL trigger
...on".
Here is a more complete example of the approach:
delimiter //
use test//
create table trigger_test
(
id int not null
)//
drop trigger if exists trg_trigger_test_ins //
create trigger trg_trigger_test_ins before insert on trigger_test
for each row
begin
declare msg varchar(128);
...
IN vs OR in the SQL WHERE Clause
...ied it with Oracle, and it was exactly the same.
CREATE TABLE performance_test AS ( SELECT * FROM dba_objects );
SELECT * FROM performance_test
WHERE object_name IN ('DBMS_STANDARD', 'DBMS_REGISTRY', 'DBMS_LOB' );
Even though the query uses IN, the Execution Plan says that it uses OR:
---------...
Why are elementwise additions much faster in separate loops than in a combined loop?
...llocations will appear at the same offset from a page-boundary.
Here's the test code:
int main(){
const int n = 100000;
#ifdef ALLOCATE_SEPERATE
double *a1 = (double*)malloc(n * sizeof(double));
double *b1 = (double*)malloc(n * sizeof(double));
double *c1 = (double*)malloc(n * sizeo...
PostgreSQL: How to pass parameters from command line?
...mewhat detailed query in a script that uses ? placeholders. I wanted to test this same query directly from the psql command line (outside the script). I want to avoid going in and replacing all the ? with actual values, instead I'd like to pass the arguments after the query.
...
Max parallel http connections in a browser?
...note1] | 1000+[^note2] |
[^note1]: tested with 72 requests , 1 domain(127.0.0.1)
[^note2]: tested with 1002 requests, 6 requests per domain * 167 domains (127.0.0.*)
[^note3]: when called in async context, e.g. in callback of setTimeout, + requestAnimationFra...
Best JavaScript compressor [closed]
...pressor and Google Closure, it compresses better than YUI on all scripts I tested it on, and it's safer than Closure (knows to deal with "eval" or "with").
Other than whitespace removal, UglifyJS also does the following:
changes local variable names (usually to single characters)
joins consecutiv...
RRSet of type CNAME with DNS name foo.com. is not permitted at apex in zone bar.com
...tionality you require. Have a look at http://docs.aws.amazon.com/Route53/latest/DeveloperGuide/CreatingAliasRRSets.html
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Is there a Java reflection utility to do a deep comparison of two objects?
I'm trying to write unit tests for a variety of clone() operations inside a large project and I'm wondering if there is an existing class somewhere that is capable of taking two objects of the same type, doing a deep comparison, and saying if they're identical or not?
...
how can I see what ports mongo is listening on from mongo shell?
...neOpts()
{
"argv" : [
"./mongod",
"-replSet",
"test",
"--rest",
"--dbpath",
"/data/test/r1",
"--port",
"30001"
],
"parsed" : {
"dbpath" : "/data/test/r1",
"port" : 30001,
"replSet" : "test",
"...