Sample Sizes for Update Statistics
The sample size that BRCONNECT uses when updating statistics was 1% or more in the past. Now it is possible to use much smaller sample sizes, which improves the performance of update statistics on large tables. You can now set sample sizes of 0.001% to 100%. This applies to the following ways of setting the sample size:
Parameter stats_sample_size in
init<DBSID>.sap
Field
OPTIO
(sample size) in the DBSTATC field
Example
To set the sample size to 0.05%, enter a value of P.05 in the brconnect —f stats -m E —s P.05
command, the stats_sample_size
parameter in init<DBSID>.sap
, or the OPTIO
field
of the DBSTATC
table.
The BRCONNECT standard formula to determine the sample size is as follows:
Number of Rows |
Sample Size in % |
|---|---|
0 - 9,999 |
100 |
10,000 - 99,999 |
30 |
100,000 - 999,999 |
10 |
1,000,000 - 9,999,999 |
3 |
10,000,000 - 99,999,999 |
1 |
100,000,000 - 999,999,999 |
0.3 |
1,000,000,000 - 9,999,999,999 |
0.1 |
10,000,000,000 - 99,999,999,999 |
0.03 |
100,000,000,000 - 999,999,999,999 |
0.01 |
1,000,000,000,000 - 9,999,999,999,999 |
0.003 |
> 9,999,999,999,999 |
0.001 |