effect is poor Core animation requires professional production, modified to be more troublesome CPU resources are relatively large, the page contains Flash animation when the page response is slow Apple's latest support, resulting in a drop in usage (2) HTML5 advantages recommended by the web, there is a unified network standard cross-platform, multi-device support seo friendly, use search engine crawl and search easy game development better interactivity audio and video
the requirements.Does not have the built-in column number Ajax,route and other functions to the core package, but the plug-in way to load.The Mixins feature is supported in component development.Different points:React relies on the virtual DOM, and Vue.js uses a DOM template. The virtual DOM used by react will perform a dirty check on the rendered results.Vue.js provides instructions, filters, and so on in the template, which makes it easy and quick to manipulate the DOM.How do I use vue.js?1.
(that is, the UI thread) and then posts the action object into the handler. In handler, it wraps the action object passed in as a message (the callback of the message is the action) and then puts it into the message loop of the UI thread. When handler processes the message again, there is a branch (the one that is not explained) that is set for it to call the runnable run method directly. At this point, it has been routed to the UI thread, so we can update the UI with no worries.As seen earlier
the exact same statement, the next execution of SQL will be compiled again.
This behavior is called "recompile (RECOMPILE)". The compilation and recompilation of the execution plan are all resources consuming.
If the execution plan can be reused, then SQL Server does not need to perform the above process to speed up the execution of instructions, and many of the statement tuning articles refer to the database reuse execution plan that means
pros a
primary key is automatically incremented by default, and using AutoIncrement guarantees that the newly inserted data will be larger than before, but it also brings a lot of extra consumption, consumes extra CPU, disk space, and the overhead of I/O disk operations. The recommendation from the official website is that it should be avoided if there is no strict need, usually it is not necessary. Here are some of the data I tested: Insert action to turn off things processing 100W data not autoincr
overhead is spent here. As a result, the iterator approach is suitable for only 1 traversal operations on the result set, and the iterator approach is particularly well suited to taking small amounts of data from the very large result sets, which iterator performance is very good. In addition, the iterator method can be used JCS buffer, in the case of buffering, the traversal operation speed of iterator mode will not be affected by the speed of database access, and get a thorough promotion. Hib
) and varchar (1) The definition of two, what is the difference? Although both can only be used to hold a single character, varchar consumes a storage location more than char. This is mainly because when you use the varchar data type, you use more than 1 bytes to store the length information. This administrative overhead of the char character type is not. ---------------------------------Summary--------------------------------------------- ----------------------------------------------- -------
by a cookie, so in the large traffic, JS, CSS, pictures placed under another domain name will save this portion of traffic.Memcache will consume some server memoryDatabase connection is a typical bottleneck, can be exempt from theFrom security Considerations: memcache/Databases > CookiesCookies are stored on the client side and need to be considered more secureMemcache, databases are on the server side, a little bit safer relative to cookiesFrom server scalability considerations: Cookies > memc
partition expression must be an integer, or an expression that returns an integer, after 5.5, some scenarios can be partitioned directly using string columns and date type columns (when using a varchar string type column, is usually the date of the string as a partition). C: If there is a primary key or a unique index column in the Partition field, all primary key columns and unique index columns must be included, and if the table has a primary key or unique index, the partition key must be a
In this article we will look at what is
python threads and processes。 Learn about Python threads and processes, and learn about
python threads and processes
the Differenceand merits.
We have introduced multi-process and multi-threading, which are the two most common ways to achieve multitasking. Now, let's discuss the pros and cons of both approaches.
First, to achieve multitasking, we typically design the
A few days ago, a classmate called me to choose the pros and cons of domestic enterprises and foreign companies, it is ridiculous that he is learning machinery; Since and I am not in an industry at all, so I just said that our IT foreign trade advantages and disadvantages, after all, interlacing as Foster.
First of all, I am the company is the U.S. Top 500 software industry (non-Internet), the absolute lead
value of the column. With respect to the Btree index, the footprint is very small, creating and using very quickly. Bitmap indexing takes up very little space because it stores only the starting and ending rowid and bitmaps of the key values. If there is a column like state in the test table, 10 rows of data are as follows:10 20 30 20 10 30 10 30 20 30Then three bitmaps will be created, as follows:BLOCK1 key=10 1 0 0 0 1 0 1 0 0 0BLOCK2 key=20 1 0 0 0 1 0 1 0 0 0BLOCK3 key=30 1 0 0 0 1 0 1 0 0
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