GoSelector
Database Column Selectivity is used as a guide by SQL Engine to influence choice of indexes for queries.
Implemented values maybe have already been added to distributed code for example by:
Do $SYSTEM.SQL.Stats.Table.SetFieldSelectivity("TEST","PropertyLen2","T1","5.1%")
Affects class storage definition adding:
<Property name="T1">
<Selectivity>5.1%</Selectivity>
</Property>
This scheduled Task:
- Does NOT modify Table / Class definitions
- Extracts existing column selectivity values found in an environment
- Profiles corresponding data values
- Generates a report of Column implemented selectivity versus actual ratio of distinct values
- Is not intended to replace or compete with other utilities
Can Use Task Schedule Output file option to create report file.
set task=##class(alwo.GoSelector).%New()
set task.ClassNamePattern="1""TEST."".E"
do task.OnTask()
| Classname |
SQL_TableName |
Property |
SQL_FieldName |
Code_Selectivity |
RecordCount |
Count_DistinctValues |
Calculated_Ratio |
| TEST.PropertyLen |
TEST.PropertyLen |
Def |
Def |
2.5% |
3 |
3 |
33.33% |
| TEST.PropertyLen2 |
TEST.PropertyLen2 |
T1 |
T1 |
5.1% |
7 |
6 |
16.67% |
| TEST.PropertyLen2 |
TEST.PropertyLen2 |
T2 |
T2 |
5.2% |
7 |
5 |
20.00% |
| TEST.PropertyLen2 |
TEST.PropertyLen2 |
T3 |
T3 |
5.3% |
7 |
4 |
25.00% |
| TEST.PropertyLen2 |
TEST.PropertyLen2 |
T4 |
T4 |
5.4% |
7 |
3 |
33.33% |
| TEST.PropertyLen2 |
TEST.PropertyLen2 |
T5 |
T5 |
5.5% |
7 |
3 |
33.33% |
Hope this utility may inspire reuse for other developer reporting needs.
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zpm install alwo-goselector 
download archive