Pool clusters provide connection pooling across the different servers in the cluster. The benefits of pool cluster are high availability, and load distribution. Pool clusters are useful in cases of large deployments in which your application needs to connect to different servers for different purposes or when you want to perform load balancing at an application level. Where a connection pool is a set of connections maintained to an individual server, in a pool clusters the Connector maintains a set of connection pools to different servers. A prerequisite is a cluster of nodes running MariaDB. In addition to connection pools, MariaDB Connector/Node.js also supports pool clusters. Another message will tell if the possible logged leak has been released. When a connection is borrowed from pool and this timeout is reached, a message will be logged to console indicating a possible connection leak. Sets a timeout to log connection borrowed from pool. If disabled or server version doesn't allows reset, pool will only rollback open transaction if any. When a connection is given back to pool, this option enables resetting the connection if the server allows it (only for MariaDB version >= 10.2.22 / 10.3.13). This option permits disabling those controls. (in ms)Īfter giving a connection back to the pool ( connection.end) connector will reset or rollback connection to ensure a valid state. 0 means validation is done each time the connection is asked. To avoid unnecessary verifications in the case of frequent reuse of connections, "minDelayValidation" permits disabling this validation if the connection has been borrowed recently. When asking for a connection to pool, the pool will validate the connection state. *: The default changes with the connectionLimit value. We recommend using a fixed pool, and so not setting this value. Permits setting a minimum number of connections in pool. Sets idle time after which a pool connection is released. In order to have connection error information, acquireTimeout must be higher than connectTimeout Timeout to get a new connection from pool in ms. The createPool(options) function supports the following pool-specific options: The callback function is defined with a single argument for the Error object if an error condition occurs in closing the pool. Function parameters have the same meaning as for the connection.batch(sql) function.Ĭloses the pool and the underlying connections after all running queries have completed. Function parameters have the same meaning as for the connection.query(sql) function. Used to run a single SQL statement or prepared statement. The first argument is for the Error object if an error condition occurs and the second argument is for a Connection object. The callback function is defined with two arguments as (error, conn). Obtains a connection as Connection object. The Pool object supports a callback function in the following functions: The base function to create a connection pool. The Callback API provides the following functions in the Connection object to create a connection pool: The last two statements display the results shown because 2 is equal to neither 1 nor 0.With Callback API, connection pools can be used. TRUE and FALSE as aliases for 1 and 0: SELECT IF(0 = FALSE, 'true', 'false') | Field | Type | Null | Key | Default | Extra | See Boolean Literals, as well as the IS operator for testing values against a boolean. However, the values TRUE and FALSE are merely aliases for 1 and 0.
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