Turboimage Database Enhancements - August 2001

TurboIMAGE
scalability II
•Lock dependency semaphores (one for each dataset)
one at a time
•lock all the necessary data blocks
•release the dependency semaphore
•Release all the data block locks at end of intrinsic
•EHWM introduced for detail dataset
•EHWM resides in dataset user label, starts from
15th double word (1 base)
•each EHWM has 21 entries, each entry
represents a block, with the 1st entry as a header
•each entry occupies 8 bytes
•allocated when the first DBPUT (if EHWM
enabled) access the dataset
•deallocate when user disable EHWM
•DBUTIL
>>ENABLE basename FOR EHWM
0th entry
1st
2nd 3rd
4th
5th 6th 7th
8th
1st 2nd 3rd 4th
5th
6th 7th 8th
Nth entry
E
H
W M
.
.
.
Blocking Factor
No. of Entries
Block number PIN
No. of records
used in block