SET_DATA_COLLECTOR_POLICY

Updates the following retention policy properties for the specified component:

• MEMORY_BUFFER_SIZE_KB

• DISK_SIZE_KB

• INTERVAL_TIME

Before you change a retention policy, you can view its current settings by querying system table DATA_COLLECTOR or by calling meta-function GET_DATA_COLLECTOR_POLICY.

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

Behavior type

Syntax

SET_DATA_COLLECTOR_POLICY('component', 'memory-buffer-size', 'disk-size' [,'interval-time']  )

Parameters

component

Specifies the retention policy to update.

Query system table DATA_COLLECTOR for component names. For example:

=> SELECT DISTINCT component, description FROM data_collector WHERE component ilike '%Depot%' ORDER BY component;
   component    |          description
----------------+-------------------------------
 DepotEvictions | Files evicted from the Depot
 DepotFetches   | Files fetched to the Depot
 DepotUploads   | Files Uploaded from the Depot
(3 rows)

memory-buffer-size

Specifies in kilobytes the maximum amount of data that is buffered in memory before moving it to disk. The policy retention policy property MEMORY_BUFFER_SIZE_KB is set from this value.

Caution

If you set this parameter to 0, the function returns with a warning that the Data Collector cannot retain any data for this component in memory or on disk.

Consider setting this parameter to a high value in the following cases:

• Unusually high levels of data collection. If memory-buffer-size is set too low, the Data Collector might be unable to flush buffered data to disk fast enough to keep up with the activity level, which can lead to loss of in-memory data.

• Very large data collector records—for example, records with very long query strings. The Data Collector uses double-buffering, so it cannot retain in memory records that are more than 50 percent larger than memory-buffer-size.

disk-size

Specifies in kilobytes the maximum disk space allocated for this component's Data Collector table. The policy retention policy property DISK_SIZE_KB is set from this value. If set to 0, the Data Collector retains only as much component data as it can buffer in memory, as specified by memory-buffer-size.

interval-time

INTERVAL data type that specifies how long data of a given component is retained in that component's Data Collector table. The retention policy property INTERVAL_TIME is set from this value. If you set this parameter to a positive value, it also changes the policy property INTERVAL_SET to t (true).

For example, if you specify component TupleMoverEvents and set interval-time to an interval of two days ('2 days'::interval), the Data Collector table dc_tuple_mover_events retains records of Tuple Mover activity over the last 48 hours. Older Tuple Mover data are automatically dropped from this table.

Note

Setting a component's policy's INTERVAL_TIME property has no effect on how much data storage the Data Collector retains on disk for that component. Maximum disk storage capacity is determined by the DISK_SIZE_KB property. Setting the INTERVAL_TIME property only affects how long data is retained by the component's Data Collector table. For details, see Configuring data retention policies.

To disable the INTERVAL_TIME policy property, set this parameter to a negative integer. Doing so reverts two retention policy properties to their default settings:

• INTERVAL_SET: f

• INTERVAL_TIME: 0

With these two properties thus set, the component's Data Collector table retains data on all component events until it reaches its maximum limit, as set by retention policy property DISK_SIZE_KB.

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Examples

See Configuring data retention policies.