CLEAR_HDFS_CACHES

Clears the configuration information copied from HDFS and any cached connections.

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 NameNode 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 NameNodes to reduce latency. This function flushes that cache.

This is a meta-function. You must call meta-functions in a top-level SELECT statement.

Behavior type

Volatile

Syntax

CLEAR_HDFS_CACHES ( )

Privileges

Superuser

Examples

The following example clears the Hadoop configuration information:

=> SELECT CLEAR_HDFS_CACHES();
 CLEAR_HDFS_CACHES
--------------
 Cleared
(1 row)

See also

Hadoop parameters