大约有 2,196 项符合查询结果（耗时：0.0095秒） [XML]
Why can't a text column have a default value in MySQL?
...ocs:
Each BLOB or TEXT value is represented internally by a separately allocated object. This is in contrast to all other data types, for which storage is allocated once per column when the table is opened.
It seems like pre-filling these column types would lead to memory usage and performance...
How to find the 'sizeof' (a pointer pointing to an array)?
... which is to stash the size somewhere. For example, if you're dynamically allocating the array, allocate a block one int bigger than the one you need, stash the size in the first int, and return ptr+1 as the pointer to the array. When you need the size, decrement the pointer and peek at the stashe...
String concatenation vs. string substitution in Python
...-squared. Some languages will optimize concatenation to the most recently allocated string, but it's risky to count on the compiler to optimize your quadratic algorithm down to linear. Best to use the primitive (join?) that takes an entire list of strings, does a single allocation, and concatenate...
Change UICollectionViewCell size on different device orientations
...ically in -viewDidLoad
self.portraitLayout = [[UICollectionViewFlowLayout alloc] init];
self.landscapeLayout = [[UICollectionViewFlowLayout alloc] init];
UIInterfaceOrientation orientationOnLunch = [[UIApplication sharedApplication] statusBarOrientation];
if (UIInterfaceOrientationIsPortrait(orie...
Iteration over std::vector: unsigned vs signed index variable
...yClass]’
instantiated from here
dependent-name ‘std::vector<T*,std::allocator<T*> >::iterator’ is parsed as a non-type, but instantiation yields a type
note: say ‘typename std::vector<T*,std::allocator<T*> >::iterator’ if a type is meant
The solution is using the ...
What is NSZombie?
...nabled then whenever an object reaches retain count 0, rather than being deallocated it morphs itself into an NSZombie instance. Whenever such a zombie receives a message, it logs a warning rather than crashing or behaving in an unpredictable way. As such, you can debug subtle over-release/autorelea...
Android Center text on canvas
...Bounds(Rect) instead. (Do not use Canvas.getClipBounds().getHeight() as it allocates memory for a Rect.)
For reasons of performance, you should allocate objects before they are used in onDraw(). As drawCenter() will be called within onDraw() the object Rect r is preallocated as a field here.
I ...
How to write a JSON file in C#?
...ly into memory, but I was able to find a couple of key places where object allocations could be reduced...... (now) Json.Net (6.0) allocates 8 times less memory than JavaScriptSerializer
Update since .Net Core 3.0
A new kid on the block since writing this is System.Text.Json which has been a...
How do I calculate tables size in Oracle
...
You might be interested in this query. It tells you how much space is allocated for each table taking into account the indexes and any LOBs on the table. Often you are interested to know "How much spaces the the Purchase Order table take, including any indexes" rather than just the table itsel...
Identity increment is jumping in SQL Server database
... since SQL Server 2012.
It now by default uses a cache size of 1,000 when allocating IDENTITY values for an int column and restarting the service can "lose" unused values (The cache size is 10,000 for bigint/numeric).
This is mentioned in the documentation
SQL Server might cache identity valu...