ttAgingLRUConfig

The ttAgingLRUConfig procedure sets the Least Recently Used (LRU) aging attributes in terms of the percentage of MB that rows occupy. You can use it on all regular tables defined with an LRU aging policy.

LRU aging enables you to maintain the amount of memory used in a TimesTen database within a specified threshold by deleting the least recently used data. Data is removed if the database space in-use exceeds the specified threshold values.

For cache groups, LRU aging is defined at the root table for the entire cache instance. LRU aging can be defined for all cache group types except for explicitly loaded autorefresh cache groups. LRU aging is defined by default on dynamic cache groups. For explicitly loaded cache groups, use time-based aging.

For cache tables, the aging policy is defined on the root table but applies to all tables in the cache group. The aging policy is defined on tables when they are created or altered, using the CREATE TABLE or ALTER TABLE SQL statements.

Required Privilege

This procedure requires no privilege to query the current values. It requires the ADMIN privilege to change the current values.

Usage in TimesTen Scaleout and TimesTen Classic

This procedure is supported in TimesTen Classic but not supported in TimesTen Scaleout.

Related Views

This procedure has no related views.

Syntax

ttAgingLRUConfig([LowUsageThreshHold], [HighUsageThreshHold], [AgingCycle])

Parameters

ttAgingLRUConfig has these optional parameters:

Parameter Type Description

Parameter	Type	Description
`lowUsageThreshold`	`BINARY_FLOAT`	Sets, displays or resets the low end of percentage of database `PermSize`, specified in decimals. The bottom of the threshold range in which LRU aging should be deactivated. The default low usage threshold is .8 (80 percent).
`highUsageThreshold`	`BINARY_FLOAT`	Sets, displays or resets the high end of percentage of database `PermSize`, specified in decimals. The top of the threshold range in which LRU aging should be activated. The default high usage threshold is .9 (90 percent).
`agingCycle`	`TT_INTEGER`	Sets, displays or resets the number of minutes between aging cycles, specified in minutes. Default is 1 minute. If you use this procedure to change the aging cycle, the cycle is reset based on the time that this procedure is called. For example, if you call this procedure at 12:00 p.m. and specify a cycle of 15 minutes, aging occurs at 12:15, 12:30, 12:45, and so on. If the cycle is set to a value of `0`, aging occurs once every second.

lowUsageThreshold

BINARY_FLOAT

Sets, displays or resets the low end of percentage of database PermSize, specified in decimals. The bottom of the threshold range in which LRU aging should be deactivated. The default low usage threshold is .8 (80 percent).

highUsageThreshold

BINARY_FLOAT

Sets, displays or resets the high end of percentage of database PermSize, specified in decimals. The top of the threshold range in which LRU aging should be activated. The default high usage threshold is .9 (90 percent).

agingCycle

TT_INTEGER

Sets, displays or resets the number of minutes between aging cycles, specified in minutes. Default is 1 minute. If you use this procedure to change the aging cycle, the cycle is reset based on the time that this procedure is called. For example, if you call this procedure at 12:00 p.m. and specify a cycle of 15 minutes, aging occurs at 12:15, 12:30, 12:45, and so on.

If the cycle is set to a value of 0, aging occurs once every second.

Result Set

ttAgingLRUConfig returns these results:

Column	Type	Description
`lowUsageThreshold`	`BINARY_FLOAT NOT NULL`	The current setting for the low end of percentage of database `PermSize`, specified in decimals.
`highUsageThreshold`	`BINARY_FLOAT NOT NULL`	The current setting for the high end of percentage of database `PermSize`, specified in decimals.
`agingCycle`	`TT_INTEGER NOT NULL`	The current setting for the number of minutes between aging cycles, specified in minutes.

Examples

To set the aging threshold to a low of 75 percent and a high of 95 percent and the aging cycle to 5 minutes, use:

CALL ttAgingLRUConfig (.75, .90, 5);
<.7500000, .9000000, 5>

To display the current LRU aging policy for all tables that defined with an LRU aging policy, call ttAgingLRUConfig without any parameters:

CALL ttAgingLRUConfig();

If the tables are defined with the default thresholds and aging cycle, the procedure returns:

<.8000000, .9000000, 1>
1 row found.

To change the low usage threshold to 60 percent, the aging cycle to 5 minutes and to retain the previous high usage threshold, use:

CALL ttAgingLRUConfig (60,,5);
< .6000000, .9000000, 5 >
1 row found.

Note:

The values of this procedure are persistent, even across system failures.

If no parameters are supplied, this procedure only returns the current LRU aging attribute settings.