Skip to content
About
Main content
Model

Restarting the whole query

The model stops being practical once nTλ approaches 1.

Tasks
tasks in the query
Task duration
hours each task runs
Failure rate
failures per task-hour

Recurring principle: Independence is assumed

How it behaves

One input on the horizontal axis, the others held fixed.

Data table
Expected full attempts by n·T·λ
n · T · λExpected attempts
01×
0.0631.06×
0.1251.13×
0.1881.21×
0.251.28×
0.3131.37×
0.3751.45×
0.4381.55×
0.51.65×
0.5631.76×
0.6251.87×
0.6881.99×
0.752.12×
0.8132.25×
0.8752.4×
0.9382.55×
12.72×
1.062.89×
1.133.08×
1.193.28×
1.253.49×
1.313.72×
1.383.96×
1.444.21×
1.54.48×
1.564.77×
1.635.08×
1.695.41×
1.755.75×
1.816.13×
1.886.52×
1.946.94×
27.39×
2.067.87×
2.138.37×
2.198.91×
2.259.49×
2.3110.1×
2.3810.8×
2.4411.4×
2.512.2×
2.5613×
2.6313.8×
2.6914.7×
2.7515.6×
2.8116.7×
2.8817.7×
2.9418.9×
320.1×
3.0621.4×
3.1322.8×
3.1924.2×
3.2525.8×
3.3127.5×
3.3829.2×
3.4431.1×
3.533.1×
3.5635.3×
3.6337.5×
3.6939.9×
3.7542.5×
3.8145.3×
3.8848.2×
3.9451.3×
454.6×
4.0658.1×
4.1361.9×
4.1965.9×
4.2570.1×
4.3174.6×
4.3879.4×
4.4484.6×
4.590×
4.5695.8×
4.63102×
4.69109×
4.75116×
4.81123×
4.88131×
4.94139×
5148×

Worked examples, recomputed

Every number the mechanisms quote for this relationship is recomputed from it, so none of them disagrees with it.

Where it appears

Each mechanism states it in its own names. The general symbol each name stands for is shown with it.

  • Execution Engine Runtime

    Once a query plan is chosen, why does the machine still sit idle, and what does each mechanism of a query runtime pay to buy that idle time back?

    Read it in place →