in flink-connector-cassandra/src/main/java/org/apache/flink/connector/cassandra/source/split/SplitsGenerator.java [125:134]
public long estimateTableSize() {
List<TokenRange> tokenRanges = getTokenRangesOfTable();
long size = 0L;
for (TokenRange tokenRange : tokenRanges) {
size += tokenRange.meanPartitionSize * tokenRange.partitionCount;
}
final float ringFraction = getRingFraction(tokenRanges);
// ringFraction can be null if the size estimates are not available
return ringFraction != 0 ? Math.round(size / ringFraction) : 0L;
}