CLEAR_HDFS_CACHES
Clears the configuration information copied from HDFS and any cached connections.
This function affects reads using the hdfs scheme in the following ways:
- This function flushes information loaded from configuration files copied from Hadoop (such as core-site.xml). These files are found on the path set by the HadoopConfDir configuration parameter.
- This function flushes information about which Name Node is active in a High Availability (HA) Hadoop cluster. Therefore, the first request to Hadoop after calling this function is slower than expected.
Vertica maintains a cache of open connections to name nodes to reduce latency. This function flushes that cache.
Syntax
CLEAR_HDFS_CACHES ( )
Privileges
Example
The following example clears the Hadoop configuration information:
=> SELECT CLEAR_HDFS_CACHES(); CLEAR_HDFS_CACHES -------------- Cleared (1 row)
