There is not only one validationQuery for all databases. On each database you have to use different validationQuery. After few hours of googling and testing I have collected this table: Database validationQuery notes hsqldb – select 1 from INFORMATION_SCHEMA.SYSTEM_USERS Oracle – select 1 from dual DB2 – select 1 from sysibm.sysdummy1 mysql – /* ping … Read more
When using Connection Pool, should one close the Connection at the end? If so, isn’t the purpose of pooling lost? And if not, how does the DataSource know when a particular instance of Connection is freed up and can be reused? I am a little confused on this one, any pointers appreciated. Yes, certainly you … Read more
If you need a standalone connection pool, my preference goes to C3P0 over DBCP (that I’ve mentioned in this previous answer), I just had too much problems with DBCP under heavy load. Using C3P0 is dead simple. From the documentation: ComboPooledDataSource cpds = new ComboPooledDataSource(); cpds.setDriverClass( “org.postgresql.Driver” ); //loads the jdbc driver cpds.setJdbcUrl( “jdbc:postgresql://localhost/testdb” ); … Read more
After a little bit of research along with help from some of the answers here: SELECT 1 H2 MySQL Microsoft SQL Server (according to NimChimpsky) PostgreSQL SQLite Hive SELECT 1 FROM DUAL Oracle SELECT 1 FROM any_existing_table WHERE 1=0 or SELECT 1 FROM INFORMATION_SCHEMA.SYSTEM_USERS or CALL NOW() HSQLDB (tested with version 1.8.0.10) Note: I tried … Read more
Database connection pooling is a method used to keep database connections open so they can be reused by others. Typically, opening a database connection is an expensive operation, especially if the database is remote. You have to open up network sessions, authenticate, have authorisation checked, and so on. Pooling keeps the connections active so that, … Read more
Connection pooling is handled as in any other ADO.NET application. Entity connection still uses traditional database connection with traditional connection string. I believe you can turn off connnection pooling in connection string if you don’t want to use it. (read more about SQL Server Connection Pooling (ADO.NET)) Never ever use global context. ObjectContext internally implements … Read more
DBCP is out of date and not production grade. Some time back we conducted an in-house analysis of the two, creating a test fixture which generated load and concurrency against the two to assess their suitability under real life conditions. DBCP consistently generated exceptions into our test application and struggled to reach levels of performance … Read more
The primary committer to node-mongodb-native says: You open do MongoClient.connect once when your app boots up and reuse the db object. It’s not a singleton connection pool each .connect creates a new connection pool. So, to answer your question directly, reuse the db object that results from MongoClient.connect(). This gives you pooling, and will provide … Read more