Solver
The Solver step solves linear programming and mixed-integer programming problems from PlaidCloud tables. Use it when a workflow needs to choose values that minimize or maximize an objective while satisfying linear constraints.
Solver runs in a workflow job pod and writes results back to project tables.
Inputs
Section titled “Inputs”Configure four input tables. Each input has a source table, data mapping, and filters. PlaidCloud translates those settings into the database query used to read each input, so selection happens before Solver receives the rows.
Variables
Section titled “Variables”One row per decision variable.
| Column | Description |
|---|---|
variable_id |
Unique variable name used by the other input tables. |
lower_bound |
Minimum value. Leave blank for no lower bound. |
upper_bound |
Maximum value. Leave blank for no upper bound. |
type |
continuous, integer, or binary. Binary variables use bounds 0 and 1. |
Objective
Section titled “Objective”One row per variable with a non-zero objective coefficient.
| Column | Description |
|---|---|
variable_id |
Variable from the Variables input. |
coefficient |
Objective coefficient for that variable. |
Variables missing from this table use coefficient 0.
Constraints
Section titled “Constraints”One row per linear constraint.
| Column | Description |
|---|---|
constraint_id |
Unique constraint name used by the Coefficients input. |
lower_bound |
Minimum allowed activity. Leave blank for no lower bound. |
upper_bound |
Maximum allowed activity. Leave blank for no upper bound. |
Set the same lower and upper bound for an equality constraint.
Coefficients
Section titled “Coefficients”Sparse matrix of constraint coefficients.
| Column | Description |
|---|---|
constraint_id |
Constraint from the Constraints input. |
variable_id |
Variable from the Variables input. |
coefficient |
Coefficient for that variable in that constraint. |
Solver Options
Section titled “Solver Options”| Option | Description |
|---|---|
| Objective Direction | Choose Minimize or Maximize. |
| Time Limit | Optional runtime limit in seconds. |
| MIP Gap | Optional relative MIP gap for mixed-integer problems. |
| Enable Presolve | Let the solver simplify the model before solving. |
| Use Custom Resources | Set CPU cores and memory for the job pod. |
Outputs
Section titled “Outputs”Solver writes three output tables.
Solution Table
Section titled “Solution Table”Contains one row per variable with the solved value, bounds, variable type, objective coefficient, and reduced cost when available.
Constraint Results Table
Section titled “Constraint Results Table”Contains one row per constraint with activity, bounds, slack, and dual value when available.
Summary Table
Section titled “Summary Table”Contains one row with solver status, objective value, runtime, MIP gap, MIP dual bound, node count, iteration count, variable count, and constraint count.
Status Behavior
Section titled “Status Behavior”An optimal solve completes the step successfully. If the solver returns a usable solution with a non-optimal status, the step finishes with a warning and still writes the output tables. If no usable solution is available, the step fails with the solver status message.