setup test case for dataset common fields

[pindge]

Fixes: #433 and #431

Scope

• rework logic for datasets sampling as tablesample logic can return zero rows and its much more expensive to run compared with order by random
• add test case for different sampling percentage

UI Changes

• add heading for common fields and hover over information
  
  

Performance Comparison

odc=> select count(*) from agdc.dataset tablesample system (0.2) where dataset_type_ref = 1;
 count 
-------
    46
(1 row)

odc=> EXPLAIN select count(*) from agdc.dataset tablesample system (0.2) where dataset_type_ref = 1;
                             QUERY PLAN                              
---------------------------------------------------------------------
 Aggregate  (cost=29393.86..29393.87 rows=1 width=8)
   ->  Sample Scan on dataset  (cost=0.00..29393.81 rows=19 width=0)
         Sampling: system ('0.2'::real)
         Filter: (dataset_type_ref = 1)
(4 rows)

odc=> \q^C
odc=> EXPLAIN select id from agdc.dataset where dataset_type_ref  =1 order by random() limit 46;
                                                     QUERY PLAN                                                     
--------------------------------------------------------------------------------------------------------------------
 Limit  (cost=24471.98..24472.09 rows=46 width=24)
   ->  Sort  (cost=24471.98..24495.13 rows=9260 width=24)
         Sort Key: (random())
         ->  Index Scan using ix_agdc_dataset_dataset_type_ref on dataset  (cost=0.43..24169.94 rows=9260 width=24)
               Index Cond: (dataset_type_ref = 1)
(5 rows)

[codecov]

Codecov Report

Base: 86.95% // Head: 86.95% // Increases project coverage by +0.00% 🎉

Coverage data is based on head (ebc1223) compared to base (f6b233c).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #432   +/-   ##
========================================
  Coverage    86.95%   86.95%           
========================================
  Files           25       25           
  Lines         3165     3158    -7     
========================================
- Hits          2752     2746    -6     
+ Misses         413      412    -1     

Impacted Files	Coverage Δ
cubedash/summary/_stores.py	92.15% <100.00%> (+0.08%)	⬆️

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[jeremyh]

Looks good, thanks Pin!

We could also squash those two queries back into one query to keep latency smaller, but this is a good improvement as-is.