/**
* Computes the number of atomic cells in a cell identified by a list of members.
*
* <p>The method may be expensive. If the value is not in the cache, computes it immediately using
* a database access. It uses an aggregate table if applicable, and puts the value into the cache.
*
* <p>Compare with {@link #evaluateAtomicCellCount(RolapEvaluator)}, which gets the value from the
* cache but may lie (and generate a cache miss) if the value is not present.
*
* @param cube Cube
* @param memberList Coordinate members of cell
* @return Number of atomic cells in cell
*/
private static double computeAtomicCellCount(RolapCube cube, List<RolapMember> memberList) {
// Implementation generates and executes a recursive MDX query. This
// may not be the most efficient implementation, but achieves the
// design goals of (a) immediacy, (b) cache use, (c) aggregate table
// use.
final StringBuilder buf = new StringBuilder();
buf.append("select from ");
buf.append(cube.getUniqueName());
int k = 0;
for (Member member : memberList) {
if (member.isMeasure()) {
member = cube.factCountMeasure;
assert member != null : "fact count measure is required for writeback cubes";
}
if (!member.equals(member.getHierarchy().getDefaultMember())) {
if (k++ > 0) {
buf.append(", ");
} else {
buf.append(" where (");
}
buf.append(member.getUniqueName());
}
}
if (k > 0) {
buf.append(")");
}
final String mdx = buf.toString();
final RolapConnection connection = cube.getSchema().getInternalConnection();
final Query query = connection.parseQuery(mdx);
final Result result = connection.execute(query);
final Object o = result.getCell(new int[0]).getValue();
return o instanceof Number ? ((Number) o).doubleValue() : 0d;
}
