Hi All,
I have been using Cassandra 0.7.2 and 0.7.4 with Thrift API (using Java).
I noticed that if I am querying a Column Family with indexed columns
sometimes I get a duplicate result in get_indexed_slices depending on the
number of rows in the CF and the count that I set in IndexClause.count.
It also depends on the order of rows in CF.
For example consider the following CF that I call Attributes:
create column family Attributes with comparator=UTF8Type
and column_metadata=[
{column_name: range_id, validation_class: LongType, index_type:
KEYS},
{column_name: attr_key, validation_class: UTF8Type, index_type:
KEYS},
{column_name: attr_val, validation_class: BytesType,
index_type: KEYS}
];
And suppose I have the following rows in the CF:
key range_id attr_key attr_val
"1/@1/0", 1, "A", "1"
"1/5/0", 1, "B", "1000"
"3/@1/0", 2, "A", "1"
"3/5/0", 2, "B", "1001"
"5/@1/0", 3, "A", "2"
"5/5/0", 3, "B", "1002"
"7/@1/0", 4, "A", "2"
"7/5/0", 4, "B", "1003"
Now if I have a query with IndexClause like this (in pseudo code):
attr_key == "A" AND attr_val == "1"
with indexClause.count = 4;
Then I ill get the rows with the following keys from get_indexed_slices :
"1/@1/0", "3/@1/0", "3/@1/0"
The last key is a duplicate!
This is very sensitive to the order of rows in the CF and the number of rows
and the number you set in indexClause.count. I noticed when the number of
rows in the CF is twice the indexClause.count this issue might happen
depending on the order of rows in CF!
This seems a bug. And it occurs in both 0.7.2 and 0.7.4.
Is there a solution to this problem?
Many Thanks,
Sam
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