src/java/org/apache/cassandra/db/index/SecondaryIndexManager.java
/**
     * Removes a existing index
     * @param column the indexed column to remove
     * @throws IOException 
     */
Removes a existing index
@param column the indexed column to remove
@throws IOException
Removes a existing index @param column the indexed column to remove @throws IOException
public void removeIndexedColumn(ByteBuffer column) throws IOException
    {
        SecondaryIndex index = indexesByColumn.remove(column);
        if (index == null)
            return;
        if (index instanceof PerRowSecondaryIndex)
        {
            index.removeColumnDef(column);
            if (index.getColumnDefs().isEmpty())
                rowLevelIndexMap.remove(index.getClass());
        }
        index.removeIndex(column);
        SystemTable.setIndexRemoved(baseCfs.metadata.ksName, index.getNameForSystemTable(column));
    }
public void removeIndexedColumn ( ByteBuffer column ) throws IOException { SecondaryIndex index = indexesByColumn . remove ( column ) ; if ( index == null ) return ; if ( index instanceof PerRowSecondaryIndex ) { index . removeColumnDef ( column ) ; if ( index . getColumnDefs ( ) . isEmpty ( ) ) rowLevelIndexMap . remove ( index . getClass ( ) ) ; } index . removeIndex ( column ) ; SystemTable . setIndexRemoved ( baseCfs . metadata . ksName , index . getNameForSystemTable ( column ) ) ; }
Removes a existing index
 @param column the indexed column to remove
 @throws IOException
Removes a existing index @param column the indexed column to remove @throws IOException
// Remove this column from from row level index map //If now columns left on this CF remove from row level lookup