Announcement
Collapse
No announcement yet.
Maximum file sizes - how to determine "key length"
Collapse
X
-
Ryan,
The Maximum number of records is limited by the RRN definition which is defined as an unsigned integer value. (4.29B) This limit is per file member/partition.
I'm not sure of the conditions of when it could actually be less than the minimum IBM describes, but it can never be larger. The other limiting factor is the 1.7TB size limit per file.
Jim
Leave a comment:
-
Maximum file sizes - how to determine "key length"
Hello,
The machine I'm looking at is V7R1
Database file sizes states the following;
2 states the following;Number of records contained in a file member 4 294 967 294 records2
For files with keyed sequence access paths, the maximum number of records in a member varies and can be estimated using the following formulas.
When ACCPTHSIZ(*MAX4GB) is specified, use the following formula:
2,867,200,000
10 + (.8 x key length)
When ACCPTHSIZ(*MAX1TB) is specified, use the following formula:
725,680,000,000
12 + (.8 x key length)
Code:Access path size . . . . . . . . . . . . . : ACCPTHSIZ *MAX1TB Access path logical page size . . . . . . . : PAGESIZE *KEYLEN Maximum key length . . . . . . . . . . . . : 29 Maximum record length . . . . . . . . . . . : 168
725,680,000,000/ 12 + (0.8 * 29) = 20,615,909,090.91
Which is 5x the stated initially stated value, I was expecting the result would be less than 4.295B.
So is it genuinely the case that if you have sequenced access paths you can have more records? Or is "Maximum key length" the wrong value to use?
Many Thanks,
RyanTags: None
Leave a comment: