The Main IQ Store blocks message displays information about use of the blocks and buffers in the Main IQ Store.
This line in the IQ message log (.iqmsg file) describes the permanent Main IQ Store:
Main Blks: U63137/6%, Buffers: U12578/L7
Item |
Description |
|---|---|
U# |
Number of blocks in use. |
#% |
Percentage of database filled. |
Buffers: U# |
Number of buffers in use. Normally this will be 100% because the buffer manager leaves buffers in memory until the buffer needs to be used for some other data. In general, the buffers used and buffers locked numbers are meaningless, because IQ uses buffers as aggressively and efficiently as it can. Note: This value will grow to maximum
number of buffers that fit in the main buffer cache. The number
increments whenever a buffer is allocated, but only decrements when
a buffer is destroyed, not when it is unlocked or flushed. Objects
in the temporary cache release their buffers when they are finished,
but in the main cache, IQ may or may not destroy the buffers because
as long as a buffer is unlocked, it is available for reuse, whether
it is empty, contains data, or contains destroyed data.
|
L# |
Number of locked buffers. A locked buffer is a buffer that is in use and cannot be removed from the cache. IQ locks buffers of some objects, such as hash objects, to keep them in memory. It locks buffers of other objects, such as a sort, depending on the workload and what it considers a fair share for that object. This number increments whenever you request a buffer. If you exceed the maximum while running a script, the command that exceeds it will fail and subsequent commands may complete incorrectly. Note: Buffer locks do not take any memory. A locked buffer
has a flag set in the in-memory structure and the flag exists whether
or not the buffer is locked.
|
Recognizing when the server is low on disk space and adding a new dbspace before the server runs out of space is important. For an example of using an event handler to monitor disk space usage and to notify you when available space is low during a load, see the section Monitoring disk space usage.