本文整理汇总了Java中org.apache.cassandra.db.index.SecondaryIndexSearcher.highestSelectivityIndex方法的典型用法代码示例。如果您正苦于以下问题：Java SecondaryIndexSearcher.highestSelectivityIndex方法的具体用法？Java SecondaryIndexSearcher.highestSelectivityIndex怎么用？Java SecondaryIndexSearcher.highestSelectivityIndex使用的例子？那么恭喜您, 这里精选的方法代码示例或许可以为您提供帮助。您也可以进一步了解该方法所在类org.apache.cassandra.db.index.SecondaryIndexSearcher的用法示例。
在下文中一共展示了SecondaryIndexSearcher.highestSelectivityIndex方法的2个代码示例，这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞，您的评价将有助于系统推荐出更棒的Java代码示例。
示例1: estimateResultRowsPerRange
import org.apache.cassandra.db.index.SecondaryIndexSearcher; //导入方法依赖的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();
}
示例2: estimateResultRowsPerRange
import org.apache.cassandra.db.index.SecondaryIndexSearcher; //导入方法依赖的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();
}