Ethereum Berkeley DB

1. The simplest way is to use jQuery

to create a div from form in the page, such as id = S1
and then get a button for the position you want
the order to add is as follows
after clicking this button,
$(#) 39# s1'). append('& lt; div id=" s2"&# 39;& gt; Here's what you want to add & lt/ div>)< br />
$('# s1'). remove('# s2') Delete the element with ID of S2 in S1

you need to use this function flexibly, which can include selecting the types of fields to add as follows, pulling more fields to select
or adding or deleting in your specified fields, or even calling the values given by other pages

this is mainly the function of JS
you should study jque more It's not complicated

2. 1. Download Berkeley DB software package. The following link contains the version history of Berkeley DB:
http://www.oracle.com/technology/global/cn/software/procts/berkeley-db/db/index.html
2 decompression, needless to say< br />3 cd build_ UNIX
4.. / list / configure
5 make
6 make install (trilogy, you should understand)
PS: at this point, it should be considered that the installation is successful. It's better to use super permissions to execute the above commands< br />7 echo /etc/ld.so.conf /usr/local/BerkeleyDB5.3/lib
8 ldconfig

3. Are you wrong about connection pool
a connection can only correspond to one thread. After it is used up, it will be returned to the connection pool, not shared!!!

4. When compiling Berkeley DB in VS2008 MFC project, there will be compilation errors in dB. H file. The reason for the errors is dB_ TYPE，DB_ Unkown has been defined in other system header files. One of the solutions is to define dB in dB. H_ TYPE，DB_ Add the following statement before unknown< br />#ifdef DB_ UNKNOWN
#undef DB_ UNKNOWN
#endif
#ifdef DBTYPE
#undef DBTYPE
#else
#define DBTYPE BDBTYPE
#endif

5. Unknown_Error

6. As crawler grabs more and more web pages, the ArrayList or HashMap of Java subband is not enough for storage, and the speed can not meet our needs. Therefore, Berkeley DB, a small memory based database, is recommended here. It is an embedded database, which refers to the database embedded in the application.

7. Configuration error, followed by the error message
DB should be database
Berkeley, which I don't know. Maybe the Berkeley database of the corresponding user and local in the file name
is wrong,
configuration error, Unable to find the fourth database in Berkeley (DB4)
configuration failure srclib / APR util (I don't know anything about this)
SCR should be screen, lib should be library, and appearance utilities may be behind it. It is estimated that the display database is damaged, or the loading visualization failed

8. Free databases in the open source world release time: 2011-11-2209:34:30 source: CSDN comments: 0 Click: 1476 times space Sina Weibo Tencent Weibo Renren Douban cyberspace socang Kaixin replication 0 open source database mysqlMySQL is an open source small relational database management system developed by mysqlab company of Sweden. At present, MySQL is widely used in small and medium-sized websites on the Internet. Because of its small size, fast speed and low total cost of ownership, especially the open source database mysqlMySQL is an open source small relational database management system developed by mysqlab of Sweden. At present, MySQL is widely used in small and medium-sized websites on the Internet. Because of its small size, fast speed, low total cost of ownership, especially open source, many small and medium-sized websites choose MySQL as the website database in order to rece the total cost of ownership. Inventory: MySQL, the free database software in the open source community, provides APIs for a variety of programming languages, including C, C + +, C #, Delphi, Eiffel, Java, Perl, PHP, python, ruby and TCL. And it is written in C and C + +, using a variety of compilers for testing, so MySQL can ensure that the source code has a strong portability. Such a database can naturally support almost all operating systems, from UNIX, Linux to windows, including AIX, bsdi, FreeBSD, HP-UX, Linux, MacOS, Novell Netware, NetBSD, OpenBSD, OS / 2wrap, Solaris, SunOS, windows and other operating systems. Most importantly, it is a large database that can handle tens of millions of records. At the same time, MySQL has also proced many branch versions of the database, which are also very worthy of recommendation. The first is MariaDB, which is a branch version of MySQL using the Maria storage engine. It is a free and open source database server developed by Michael widenius, the original author of MySQL. Compared with MySQL, the strength of MariaDB lies in its engines, including Maria storage engine, pbxt storage engine, xtradb storage engine and federated x storage engine. It can query processing faster, run faster, test better functions and support Unicode sorting. The second is rcona, which improves the MySQL database server and has a significant improvement in function and performance compared with MySQL. This version improves the performance of InnoDB under high load. At the same time, it also provides some very useful performance diagnostic tools for DBAs, and provides many parameters and commands to control server behavior. The third is percona server, which uses Google MySQL tools, provenscaling and openquery to transform mysql. Moreover, it only contains the server version of MySQL, and does not provide corresponding improvements to MySQL connector and GUI tools. Non relational database NoSQL literally means not only SQL, which is regarded as a brand new revolutionary movement of database by the instry. It was proposed in the early days, and the trend of development is more and more high in 2009. The proponents of NoSQL advocate the use of non relational data storage. Compared with the current overwhelming use of relational database, this concept is undoubtedly a new injection of thinking. Inventory: the free database software of open source community. Of course, NoSQL has made great progress with the rise of Internet Web2.0 website. The key requirement is that the traditional relational database can't cope with Web2.0 websites, especially the super large and highly concurrent SNS type Web2.0 pure dynamic websites, which exposes many problems that are difficult to overcome, while the non relational database has developed very rapidly e to its own characteristics. The first recommendation is Oracle nosqldatabase, which is a community version. Oracle's nosqldatabase is one of the components of bigdataappliance, which was released in Oracle global encyclopedia on October 4. Bigdataappliance is a system integrating Hadoop, nosqldatabase, Oracle database Hadoop adapter, Oracle database Hadoop loader and R language. Next, Membase is recommended. Membase is a new heavyweight member of NoSQL family. Membase is an open source project with Apache 2.0 license. The project is hosted on github.sourcetarballs, and the beta version of Linux binary package can be downloaded at present. The proct is mainly developed by members of northscale's memcached core team, including engineers from Zynga and NHN, two major contributors, which are suppliers of large online games and community cyberspace. Moreover, Membase is easy to install and operate, and can be easily extended from a single node to a cluster. It also realizes plug and play function for memcached (compatibility of wired protocol), which provides a relatively low threshold for developers and operators in application. As a caching solution, memcached has been widely used in different types of fields (especially in large capacity Web Applications). Part of the basic code of memcached is directly applied to the front end of the Membase server. By compatible with a variety of programming languages and frameworks, Membase has good reusability. In terms of installation and configuration, Membase provides an effective graphical interface and programming interface, including configurable alarm information. The goal of Membase is to provide external linear scalability, including replication for unified nodes in order to increase cluster capacity. In addition, redistribution of stored data is still necessary. The third recommendation is Hibari. Hibari, which means "Skylark" in Japanese, is a database engine for high reliability and big data storage. It can be used in cloud computing environments, such as webmail, SNS and other environments requiring T / P level data storage. Hibari also supports Java, C / C + +, python, ruby and Erlang clients. The fourth recommendation is memcachedb. This is an open source project opened by sina.com developers. It adds Berkeley DB's persistent storage mechanism and asynchronous primary and secondary replication mechanism to the memcached distributed cache server, which enables memcached to have transaction recovery ability, persistence ability and distributed replication ability. It is very suitable for requiring ultra-high performance read-write speed, but does not require strict transaction constraints, Application scenarios that can be persisted, such as memcachedb, are applied to Sina blog. The fifth recommendation is leveldb. This is a very efficient kV database implemented by Google. The current version 1.2 can support the amount of data at the level of bill. At this level, it has very high performance, mainly e to its good design, especially LSM algorithm. Leveldb is a single process service with very high performance. On a four Q6600 CPU machine, it can write more than 40W data per second, while the performance of random reading is more than 10W per second. Advantages of XML database XML database is a data management system that supports the storage and query of XML documents. In the system, developers can query, export and serialize the XML documents in the database. At present, there are three types of XML Databases: XML enabled database (xedb), which can process XML; Native XML database (NXD) is a pure XML database; Hybrid XML database (HXD) is a hybrid XML database. The first generation of XML support in relational database is to segment (or decompose) documents to fit relational tables or store documents as characters or binary large objects (CLOB or BLOB) intact. Either of these two approaches attempts to cast an XML model into a relational model. However, these two methods have great limitations in function and performance. The hybrid model stores XML in a DOM like model. XML data is formatted as buffered data pages for quick navigation and query execution, as well as simplified indexing. Here, the first XML database to recommend is Sedna. It is known as an original XML database, providing full-featured core database services, including persistent storage, acid transaction, index, security, hot standby, utf8 and so on. The W3C XQuery specification is implemented, which supports full-text search and node level update operation. The second XML database is Basex. This database is used to store compressed XML data, and provides efficient implementation of XPath and XQuery. At the same time, it also provides a front-end operation interface. Inventory: the third free database software recommended by the open source community is xmldb. This database uses a relational database to store any XML document. Because of the storage mechanism, the search speed of the document is very fast, and the implementation of XSL transformation is also very fast. Xmldb also provides a PHP mole, which can be used in web applications. The fourth recommendation is x-hive / DB. It is a powerful exclusive XML database designed for software developers who need advanced XML data processing and storage functions. The x-hive / DB Java API contains methods for storing, querying, retrieving, transforming, and publishing XML data. Compared with traditional relational database, XML database has the following advantages: first, XML database can access and manage semi-structured data effectively. For example, web content is a kind of semi-structured data, while traditional relational database can not manage such semi-structured data effectively. Second, provide operations on tags and paths. Traditional database language allows to operate on the value of data elements, but not on the name of elements. Semi structured database provides the operation on label name and path. Thirdly, when the data itself has hierarchical characteristics, XML data format can clearly express the hierarchical characteristics of the data, so XML database is easy to operate the hierarchical data. XML database is suitable for managing data sets with complex data structure. If information has been stored in XML format, XML database is concive to document storage and retrieval; It can retrieve documents in a convenient and practical way and provide high-quality full-text search engine. In addition, XML database can store and query heterogeneous document structure, providing support for heterogeneous information access.

9. Mysql database has a variety of storage engines: MyISAM, InnoDB, merge, memory (heap), BDB (Berkeley DB), extract, fed, archive, CSV, Blackhole and so on. The most common ones are MyISAM and InnoDB. The following mainly explains the differences between MyISAM and InnoDB. MyISAM engine is a non transactional engine, providing high-speed storage and retrieval, as well as full-text search capabilities, suitable for frequent query applications such as data warehouse. In MyISAM, a table is actually saved as three files,. Frm stores table definition,. MyD stores data,. MYI stores index. MyISAM is supported in all MySQL configurations. It is the default storage engine unless you configure Mysql to use another engine by default. Other non transactional storage engines in MySQL server (such as MyISAM) follow different data integrity paradigms, which are called "atomic operations". According to transaction terms, MyISAM table always works efficiently in autocommit = 1 mode. Atomic operations usually provide comparable integrity and better performance. Compared with the fastest transactional table optimized and adjusted, it is 3-5 times faster. Since the MySQL server supports two paradigms, you can decide whether to use the speed of atomic operations to better serve your applications, or use transactional features. The selection can be made according to the table. InnoDB is a transaction engine. It provides MySQL with transaction security (acid compatible) storage engine with the ability of commit, rollback and crash recovery. All the data are stored in one or more data files, supporting a locking mechanism similar to Oracle. Generally, it is widely used in OLTP applications. If the InnoDB configuration option is not specified, MySQL will create an automatic extended data file named ibdata1 and two files named IB in the MySQL data directory_ Logfile0 and IB_ Log file of logfile1. InnoDB locks at the row level and also provides an Oracle style consistent non locked read in the select statement. These features increase multi-user deployment and performance. There is no need to expand locking in InnoDB, because row level locking in InnoDB is suitable for very small space. InnoDB also supports foreign key enforcement. In SQL query, you can freely mix InnoDB type tables with other MySQL table types, even in the same query. InnoDB is designed for maximum performance when dealing with large amounts of data. Its CPU efficiency may be unmatched by any other disk based relational database engine. InnoDB storage engine is fully integrated with MySQL server. InnoDB storage engine maintains its own buffer pool for caching data and indexes in main memory. InnoDB stores its tables and indexes in a table space, which can contain several files. InnoDB tables can be of any size, even on operating systems where the file size is limited to 2GB. InnoDB is also included in all MySQL 5.1 binary distributions by default.

10.

MySQL database has a variety of storage engines: for example: MyISAM, InnoDB, merge, memory (heap), BDB (Berkeley DB), extract, federated, archive, CSV, Blackhole, etc. the most common ones are MyISAM and InnoDB. The following mainly explains the differences between MyISAM and InnoDB

MyISAM engine is a non transactional engine, which provides high-speed storage and retrieval, as well as full-text search capabilities, and is suitable for frequent query applications such as data warehouse. In MyISAM, a table is actually saved as three files,. Frm stores table definition,. MyD stores data,. MYI stores index. MyISAM is supported in all MySQL configurations. It is the default storage engine unless you configure Mysql to use another engine by default

other non transactional storage engines in MySQL server (such as MyISAM) follow different data integrity paradigms, which are called "atomic operations". According to transaction terms, MyISAM table always works efficiently in autocommit = 1 mode. Atomic operations usually provide comparable integrity and better performance. Compared with the fastest transactional table optimized and adjusted, it is 3-5 times faster. Since the MySQL server supports two paradigms, you can decide whether to use the speed of atomic operations to better serve your applications, or use transactional features. The selection can be made according to the table

InnoDB is a transaction engine. It provides MySQL with transaction security (acid compatible) storage engine with the ability of commit, rollback and crash recovery. All the data are stored in one or more data files, supporting a locking mechanism similar to Oracle. Generally, it is widely used in OLTP applications. If the InnoDB configuration option is not specified, MySQL will create an automatic extended data file named ibdata1 and two files named IB in the MySQL data directory_ Logfile0 and IB_ Log file of logfile1

InnoDB locks at the row level and also provides an Oracle style consistent non locked read in the select statement. These features increase multi-user deployment and performance. There is no need to expand locking in InnoDB, because row level locking in InnoDB is suitable for very small space. InnoDB also supports foreign key enforcement. In SQL query, you can freely mix InnoDB type tables with other MySQL table types, even in the same query

InnoDB is designed for the maximum performance when dealing with a large amount of data. Its CPU efficiency may be unmatched by any other disk based relational database engine. InnoDB storage engine is fully integrated with MySQL server. InnoDB storage engine maintains its own buffer pool for caching data and indexes in main memory

InnoDB stores its tables and indexes in a table space, which can contain several files. InnoDB tables can be of any size, even on operating systems where the file size is limited to 2GB. InnoDB is also included in all MySQL 5.1 binary distributions by default