@Override
public long computeIndexLookupCosts(
IndexDescriptor index, TableDescriptor baseTable, long cardinality) {
PageSize indexPageSize = index.getSchema().getPageSize();
PageSize tablePageSize = baseTable.getSchema().getPageSize();
long BTreeCost =
(index.getStatistics().getTreeDepth() - 2)
* (getReadCost(indexPageSize) + randomReadOverhead);
long pageNbr;
if (cardinality == baseTable.getStatistics().getCardinality())
pageNbr = index.getStatistics().getNumberOfLeafs() + 1;
else
pageNbr =
(long)
Math.ceil(
index.getStatistics().getNumberOfLeafs()
* 1.0f
* cardinality
/ baseTable.getStatistics().getCardinality());
long scanCost = randomReadOverhead + pageNbr * getReadCost(tablePageSize);
return BTreeCost + scanCost;
}
@Override
public long computeTableScanCosts(TableDescriptor table) {
PageSize pageSize = table.getSchema().getPageSize();
int pageNbr = table.getStatistics().getNumberOfPages();
return randomReadOverhead + pageNbr * getReadCost(pageSize);
}
@Override
public long computeFetchCosts(
TableDescriptor fetchedTable, long cardinality, boolean sequential) {
PageSize pageSize = fetchedTable.getSchema().getPageSize();
int totalPages = fetchedTable.getStatistics().getNumberOfPages();
if (sequential) {
float k = 1.0f * (totalPages - 1) / totalPages;
// double nbrPages = (1/k - 1/(k- Math.pow(k, 2))) * Math.pow(k, cardinality)+ 1/(1-k);
double nbrPages = Math.floor((1 - Math.pow(k, cardinality)) / (1 - k));
// nbrPages = 249.05f;
double ratio = 1 - (1.0f * nbrPages / totalPages) * (7.0f / 8.0f);
/*System.out.println("k : " + k);
System.out.println("total pages : " + totalPages);
System.out.println("pages : " + nbrPages);
System.out.println("ratio : " + ratio);
System.out.println("PageSize : " + pageSize.toString());
*/
return (long) Math.floor(nbrPages * (getReadCost(pageSize) + ratio * randomReadOverhead));
} else {
double B = Math.pow(10 * totalPages, 1.0 / 0.66);
double H = Math.min(Math.log(cardinality) / Math.log(B), 0.8);
return (long)
Math.floor(cardinality * (1 - H) * (getReadCost(pageSize) + randomReadOverhead));
}
}
