private boolean testPlan(TableFilter[] list) {
Plan p = new Plan(list, list.length, condition);
double costNow = p.calculateCost(session);
if (cost < 0 || costNow < cost) {
cost = costNow;
bestPlan = p;
return true;
}
return false;
}
/** Calculate the best query plan to use. */
void optimize() {
calculateBestPlan();
bestPlan.removeUnusableIndexConditions();
TableFilter[] f2 = bestPlan.getFilters();
topFilter = f2[0];
for (int i = 0; i < f2.length - 1; i++) {
f2[i].addJoin(f2[i + 1], false, false, null);
}
for (TableFilter f : f2) {
PlanItem item = bestPlan.getItem(f);
f.setPlanItem(item);
}
}
private void calculateBruteForceSome() {
int bruteForce = getMaxBruteForceFilters(filters.length);
TableFilter[] list = new TableFilter[filters.length];
Permutations<TableFilter> p = Permutations.create(filters, list, bruteForce);
for (int x = 0; !canStop(x) && p.next(); x++) {
// find out what filters are not used yet
for (TableFilter f : filters) {
f.setUsed(false);
}
for (int i = 0; i < bruteForce; i++) {
list[i].setUsed(true);
}
// fill the remaining elements with the unused elements (greedy)
for (int i = bruteForce; i < filters.length; i++) {
double costPart = -1.0;
int bestPart = -1;
for (int j = 0; j < filters.length; j++) {
if (!filters[j].isUsed()) {
if (i == filters.length - 1) {
bestPart = j;
break;
}
list[i] = filters[j];
Plan part = new Plan(list, i + 1, condition);
double costNow = part.calculateCost(session);
if (costPart < 0 || costNow < costPart) {
costPart = costNow;
bestPart = j;
}
}
}
filters[bestPart].setUsed(true);
list[i] = filters[bestPart];
}
testPlan(list);
}
}