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Post date: Oct 27, 2012 11:0:40 PM
Here is how the data moves from *_now to *_history table.
a. *_now is an external table whose data files are stored in $MASTER_DATA_DIRECTORY/gpperfmon/data. Data is stored in *_now during the period between data collection from the Command Center agents and automatic commitment to the *_history table.
b.*_tail is an external table whose data files are stored in $MASTER_DATA_DIRECTORY/gpperfmon/data. This is a transitional table for data that has been cleared from *_now but has not yet been committed to *_history. It typically only contains a few minutes worth of data.
c.*_history is a regular table that stores historical data. It is pre-partitioned into monthly partitions. Partitions are automatically added in two month increments as needed.