dbconnection

问题 I'm currently using a singleton on my web application so that there is always only one connection to the database. I want to know if it's a good idea because right now I'm having trouble with that error: Timeout expired. The timeout period elapsed prior to obtaining a connection from the pool. This may have occurred because all pooled connections were in use and max pool size was reached. Another important point is that my website is currently in dev and not a lot of people go on it so I don

问题 I use jpa+hibernate+hikariCP. Today I got connection closed error. I setted connectionTimeout and ideleTimeout properties(hikari). If in meantime use does not do any operition hikari close the pool connections auto. So that I got closed connection problem. My question how can I set properly hiker(jpa,hibernate) properties so if user comes back after 3-4 hours and try to do some operation hikari auto reconnect to db? is it possible? I use hikari v2.6.1 and hibernate v5.2.8.Final 回答1: This

问题 I'm building a project with Derby DB It works just fine when I run it in Netbeans and also as jar file when I use DB as Network Client with derbyclient.jar . But the problem is I have to distribute it so I use Embedded mode of Derby DB , As I provide derby.jar . And followed the instructions Provided Here. The only deference between Embedded & Network is we have to use this DB path (short DB name path) dbPath = "jdbc:derby:Mail_Client_Ref_Fiverr"; Instead of (full with localhost and port)

问题 I'm building a project with Derby DB It works just fine when I run it in Netbeans and also as jar file when I use DB as Network Client with derbyclient.jar . But the problem is I have to distribute it so I use Embedded mode of Derby DB , As I provide derby.jar . And followed the instructions Provided Here. The only deference between Embedded & Network is we have to use this DB path (short DB name path) dbPath = "jdbc:derby:Mail_Client_Ref_Fiverr"; Instead of (full with localhost and port)

问题 I'm trying to unit test a few .NET classes that (for good design reasons) require DbConnections to do their work. For these tests, I have certain data in memory to give as input to these classes. That in-memory data could be easily expressed as a DataTable (or a DataSet that contains that DataTable), but if another class were more appropriate I could use it. If I were somehow magically able to get a DbConnection that represented a connection to the in-memory data, then I could construct my

问题 I'm trying to unit test a few .NET classes that (for good design reasons) require DbConnections to do their work. For these tests, I have certain data in memory to give as input to these classes. That in-memory data could be easily expressed as a DataTable (or a DataSet that contains that DataTable), but if another class were more appropriate I could use it. If I were somehow magically able to get a DbConnection that represented a connection to the in-memory data, then I could construct my

问题 Context first: Apigility driven application based on Zend Framework 2. In the first version ( V1 ) I was using the ZfcBase DbMapper for the model layer. Now I'm implementing the V2 with Doctrine 2 as ORM. Apigility provides an easy switching between versions and every version can use its own DB adapter: /config/autoload/global.php / /config/autoload/local.php <?php return array( ... 'db' => array( 'adapters' => array( 'DB\\myproject_v1' => array( // settings (driver, hostname, database,

问题 Our current DB Connection provider model relies on database connectivity to use DbConnection (System.Data) based objects. We can connect to DB2 (*Nix * Windows) via OdbcConnection, but we would like to allow the use of native DB2 Drivers. Is there any way to do so (either .Net framework, OpenSource or (last choice) vendor) without breaking away from our current DAL model? 回答1: There is another method not mentioned in the article above, and that is to use DbNetData which simplifies database

问题 Which of the following two is more accurate? select numbackends from pg_stat_database; select count(*) from pg_stat_activity; 回答1: Those two requires aren't equivalent. The equivalent version of the first one would be: SELECT sum(numbackends) FROM pg_stat_database; In that case, I would expect that version to be slightly faster than the second one, simply because it has fewer rows to count. But you are not likely going to be able to measure a difference. Both queries are based on exactly the

问题 Which of the following two is more accurate? select numbackends from pg_stat_database; select count(*) from pg_stat_activity; 回答1: Those two requires aren't equivalent. The equivalent version of the first one would be: SELECT sum(numbackends) FROM pg_stat_database; In that case, I would expect that version to be slightly faster than the second one, simply because it has fewer rows to count. But you are not likely going to be able to measure a difference. Both queries are based on exactly the