The onstat -h command provides information on the buffer header hash chain used to access pages in the buffer pool.
Buffer pool page size: 2048 buffer hash chain length histogram # of chains of len 3021028 0 616286 1 238274 2 141138 3 17567 4 15102 5 12672 6 17334 7 18243 8 21599 9 29354 10 41973 11 3568 12 164 13 2 14 4194304 total chains 2999950 hashed buffs 3000000 total buffs
|# of chains||A count of the number of hash chains for which the length for members of that chain is the same.||Dec||onstat -b|
|of len||The length of the chains.||Dec|
|total chains||The number of hash chains (buckets) created.||Dec|
|hashed buffs||The number of buffer headers hashed into the hash buckets.||Dec|
|total buffs||The number of buffers in the buffer pool.||Dec|
In some earlier versions, the onstat -h command does not show up in the normal onstat command usage.
Tuning to the hash chain is performed indirectly by tuning the number of buffers. As pages are read into the buffer pool, the page number is hashed to a value for one of the hash buckets. Since there are only a limited number of hash buckets, multiple page numbers will hash to the same value and thus the same hash bucket, creating a chain. Although the onstat -h command doesn't show the length of each individual hash bucket, it does show the total number of hash buckets with a particular length.
To discuss how Oninit ® can assist please call on +1-913-674-0360 or alternatively just send an email specifying your requirements.