import org.apache.cassandra.db.index.SecondaryIndexSearcher; //导入依赖的package包/类
/**
 * Estimate the number of result rows (either cql3 rows or storage rows, as called for by the command) per
 * range in the ring based on our local data.  This assumes that ranges are uniformly distributed across the cluster
 * and that the queried data is also uniformly distributed.
 */
private static float estimateResultRowsPerRange(AbstractRangeCommand command, Keyspace keyspace)
{
    ColumnFamilyStore cfs = keyspace.getColumnFamilyStore(command.columnFamily);
    float resultRowsPerRange = Float.POSITIVE_INFINITY;
    if (command.rowFilter != null && !command.rowFilter.isEmpty())
    {
        List<SecondaryIndexSearcher> searchers = cfs.indexManager.getIndexSearchersForQuery(command.rowFilter);
        if (searchers.isEmpty())
        {
            resultRowsPerRange = calculateResultRowsUsingEstimatedKeys(cfs);
        }
        else
        {
            // Secondary index query (cql3 or otherwise).  Estimate result rows based on most selective 2ary index.
            for (SecondaryIndexSearcher searcher : searchers)
            {
                // use our own mean column count as our estimate for how many matching rows each node will have
                SecondaryIndex highestSelectivityIndex = searcher.highestSelectivityIndex(command.rowFilter);
                resultRowsPerRange = Math.min(resultRowsPerRange, highestSelectivityIndex.estimateResultRows());
            }
        }
    }
    else if (!command.countCQL3Rows())
    {
        // non-cql3 query
        resultRowsPerRange = cfs.estimateKeys();
    }
    else
    {
        resultRowsPerRange = calculateResultRowsUsingEstimatedKeys(cfs);
    }

    // adjust resultRowsPerRange by the number of tokens this node has and the replication factor for this ks
    return (resultRowsPerRange / DatabaseDescriptor.getNumTokens()) / keyspace.getReplicationStrategy().getReplicationFactor();
}
 

import org.apache.cassandra.db.index.SecondaryIndexSearcher; //导入依赖的package包/类
/**
 * Estimate the number of result rows (either cql3 rows or storage rows, as called for by the command) per
 * range in the ring based on our local data.  This assumes that ranges are uniformly distributed across the cluster
 * and that the queried data is also uniformly distributed.
 */
private static float estimateResultRowsPerRange(AbstractRangeCommand command, Keyspace keyspace)
{
    ColumnFamilyStore cfs = keyspace.getColumnFamilyStore(command.columnFamily);
    float resultRowsPerRange;
    if (command.rowFilter != null && !command.rowFilter.isEmpty())
    {
        // secondary index query (cql3 or otherwise)
        SecondaryIndexSearcher searcher = Iterables.getOnlyElement(cfs.indexManager.getIndexSearchersForQuery(command.rowFilter));
        SecondaryIndex highestSelectivityIndex = searcher.highestSelectivityIndex(command.rowFilter);
        // use our own mean column count as our estimate for how many matching rows each node will have
        resultRowsPerRange = highestSelectivityIndex.estimateResultRows();
    }
    else if (!command.countCQL3Rows())
    {
        // non-cql3 query
        resultRowsPerRange = cfs.estimateKeys();
    }
    else
    {
        if (cfs.metadata.comparator.isDense())
        {
            // one storage row per result row, so use key estimate directly
            resultRowsPerRange = cfs.estimateKeys();
        }
        else
        {
            float resultRowsPerStorageRow = ((float) cfs.getMeanColumns()) / cfs.metadata.regularColumns().size();
            resultRowsPerRange = resultRowsPerStorageRow * (cfs.estimateKeys());
        }
    }

    // adjust resultRowsPerRange by the number of tokens this node has and the replication factor for this ks
    return (resultRowsPerRange / DatabaseDescriptor.getNumTokens()) / keyspace.getReplicationStrategy().getReplicationFactor();
}
 

import org.apache.cassandra.db.index.SecondaryIndexSearcher; //导入依赖的package包/类
public SecondaryIndexSearcher createSecondaryIndexSearcher(Set<ByteBuffer> columns)
{
    return new CompositesSearcher(baseCfs.indexManager, columns);
}
 

import org.apache.cassandra.db.index.SecondaryIndexSearcher; //导入依赖的package包/类
public SecondaryIndexSearcher createSecondaryIndexSearcher(Set<ByteBuffer> columns)
{
    return new KeysSearcher(baseCfs.indexManager, columns);
}
 

import org.apache.cassandra.db.index.SecondaryIndexSearcher; //导入依赖的package包/类
protected SecondaryIndexSearcher createSecondaryIndexSearcher(Set<ByteBuffer> columns)
{
    return null;
}
 

import org.apache.cassandra.db.index.SecondaryIndexSearcher; //导入依赖的package包/类
@Override
protected SecondaryIndexSearcher createSecondaryIndexSearcher(Set<ByteBuffer> columns)
{
    return null;
}
 

import org.apache.cassandra.db.index.SecondaryIndexSearcher; //导入依赖的package包/类
public SecondaryIndexSearcher createSecondaryIndexSearcher(Set<ByteBuffer> columns)
{
    return new CompositesSearcher(baseCfs.indexManager, columns, prefixSize);
}
 

import org.apache.cassandra.db.index.SecondaryIndexSearcher; //导入依赖的package包/类
@Override
protected SecondaryIndexSearcher createSecondaryIndexSearcher(Set<ByteBuffer> columns) {
    Log.debug("Creating searcher for index %s", logName);
    return new RowIndexSearcher(secondaryIndexManager, this, columns, rowService);
}
 

import org.apache.cassandra.db.index.SecondaryIndexSearcher; //导入依赖的package包/类
@Override
protected SecondaryIndexSearcher createSecondaryIndexSearcher(Set<ByteBuffer> columns) {
    logger.info("Fake PerColumnLuceneIdx createSecondaryIndexSearcher method");
    return null;
}