coverity scan

finish ..."); } } The reason to use an integer object to make an error is to lock the integer object, but try to modify the object. When using a collection object, such as a map, in our synchronized, refer to the following code: public class Test {public static void main (string[] args) throws Exception {map When you use the map, you can see that although the map is synchronized, another thread can modify the map. Why, then? When we use a collection, synchronized locks the address of the col

Port Scan 234 Layer discovery is only to accurately discover all live host IP, identify attack surface, port scan to discover attack point, Discover open port. The port corresponds to the Network service and application program, and the vulnerability of the service-side program is hacked through the port. "All scan results, do not fully believe that" a port is a

For clustered index scanning, we first know that the data is a tree data structure arranged by the index key as the leaf node. The data in each row in the table is attached to the index key, the fastest way to perform data search for such a table is, of course, "clustered index search ". Under what circumstances is "clustered index scanning? When the condition field of the data you want to search for has no index, the query executor will read the data in the entire table one by one to confirm th

Addsublayer:_scanlayer];[Self setoverlaypickerview];Start session[_scansession startrunning];return YES;}End Scan-(void) stopreading{[_scansession stoprunning];_scansession = nil;}Scan results-(void) Captureoutput: (Avcaptureoutput *) captureoutput didoutputmetadataobjects: (Nsarray *) metadataobjectsFromconnection: (avcaptureconnection *) connection{if (metadataobjects! = Nil [metadataobjects count] > 0)

This article is applicable to the reading references of the attacker who has some in-depth knowledge about database indexes. We are easy to understand clustering index scanning and table scanning, but it is not easy to understand non-clustered index scanning. This is often confusing for beginners, the reason is that there is no need for non-clustered index scanning, because if the query results are not highly selective, clustering index scanning can be used in clustered index tables, why does a

Index range scan ): 1. for unique index, if the where condition is followed by 2. For none unique index, if the where condition is followed by =,>, 3. For composite indexes, if the bootstrap column of the composite index appears after the where condition, index range scan may be executed. Index fast full scan (index fast full

Use ZBar in iOS to scan the QR code to customize the scan interface, and use ioszbar to scan the interfaceZXing has been used in Android to identify QR codes. ZXing also has the corresponding iOS version. After understanding it, ZBar is also a common QR code recognition software, the sdks for iOS and Android are provided for use. Finally, I chose ZBar for QR code

Haha, I am in a good mood today. I am complaining about this scan problem...At present, I usually use TCP or SYN scanning. This FIN scan is not commonly used. It is also called a secret scan.The following three methods will be used for a small discussion. For more information, please advise!I. Why is TCP scanning slow? This method sends a connection request packet segment from a port on the local host to a

First, index fast Scan (index fast full scan)The index fast full scan, which is very similar to index full scan, is also suitable for all types of B-tree indexes, including unique indexes and non-unique indexes. As with the index full scan, the index fast full

The most general way to satisfy the GROUP BY clause is to scan the entire table and create a new temporary table, all rows of each group in the table should be contiguous, and then use the temporary table to locate the group and apply the cumulative function, if any. In some cases, MySQL can do a better job of accessing the index without creating a temporary table.The most important precondition for using indexes for group by is that all group by colu

The most common way to satisfy a GROUP BY clause is to scan the entire table and create a new temporary table in which all rows of each group should be contiguous, and then use the temporary table to locate the group and apply the cumulative function (if any). In some cases, MySQL can do better by indexing access without creating a temporary table.The most important prerequisite for using an index for group by is that all the group by columns referenc

MySQL optimized GROUPBY-loose index scan and compact index scan ????? The most common method to satisfy the GROUPBY clause is to scan the entire table and create a new temporary table. All rows in each group in the table should be continuous, then use the temporary table to locate the group and apply the accumulate function (if any ). In some cases, MySQL can do

SpringMVC source code deep parsing (context: component-scan) (scan and register annotation Bean) Some of our SpringMVC development projects use annotations and XML to configure beans, which have their own advantages. XML is often used for data source configuration, the services dependent on the control layer often use annotations (which won't be changed during deployment). We often use annotation @ Componen

ArticleDirectory What is the difference between a table and index scan in an execution plan? ATable ScanIs whereTable is processed row by row from beginning to end. AnIndex ScanIs whereIndex is processed row by row from beginning to end. If the index isClustered index then an index scan is really a table Scan. When you see an index

Tags: mysql group by loose Scan Compact scan Group by optimizationThe GROUP BY statement uses the B+tree index scan to be divided into two cases: loose scan, compact scan.Loose Index Scan (loosely scanned) is just a small portion of the key value that needs to be taken out o

After using Avfoundation to complete the scan code, there are 2 problems: 1, how to limit the scan range? 2. How is the barcode scanned? A friend's article helped me, specially transferred, can help the needy friend. Original: http://www.2cto.com/kf/201411/356046.html The main reason for writing this article is not to show how to use avfoundation for QR code scanning, but also to limit th

The main reason for writing this article is not to show how to use avfoundation for QR code scanning, but also to limit the scope of scanning QR code. (Because the default is full screen scanning)The project encountered the function of scanning QR code, here I gave up the use of the three-party library, and the introduction of Apple native scan. The advantage of native is that the scan is particularly fast

Use index quick full scan (indexffs) to avoid full table scan reference: IndexFastFullScanUsageToAvoidFullTableScans (DocID70135.1) applicable to: OracleDatabase Use index quick Full Scan (Index ffs) To Avoid Full Table Scan reference: index Fast Full Scan Usage To Avoid Ful

Label:0. ReferencesTable Scan, Index Scan, index Seek SQL Server–index Seek vs. Index Scan–diffefence and Usage–a simple Note How Oracle tables are accessed Difference between index seek and index scan and where applicableHow to access tables in 1.oracleIn Oracle, where table access is described, the data in the Access

[Translated from mos] Using index quick full scan (index ffs) to avoid full table scan, mosffs Using index quick full scan (index ffs) to avoid full table Scan Reference Original:Index Fast Full Scan Usage To Avoid Full Table Scans (Doc ID 70135.1) Applicable:Oracle Database