Empty Result with Secondary Index Queries with "limit 1"
--------------------------------------------------------
Key: CASSANDRA-2628
URL: https://issues.apache.org/jira/browse/CASSANDRA-2628
Project: Cassandra
Issue Type: Bug
Components: Core
Affects Versions: 0.7.5
Environment: CentOS 5.5
Reporter: Muga Nishizawa
Fix For: 0.7.6
Empty result is returned by secondary index queries with "limit 1". Cassandra
returns correct result for other numbers than "1" (e.g. limit 2, limit 3,
etc.).
You can reproduce the problem with programs attached on CASSANDRA-2406.
- 1. Start Cassandra cluster. It consists of 3 cassandra nodes and distributes
data by ByteOrderedPartitioner. Initial tokens of those nodes are ["31", "32",
"33"].
- 2. Create keyspace and column family, according to "create_table.cli",
- 3. Execute "secondary_index_insertv2.py", inserting a few hundred columns to
cluster
- 4. Here, when you first use cassandra-cli and execute following lines, you
can get correct result.
{quote}
% bin/cassandra-cli
[default@unknown] connect localhost/9160;
[default@unknown] use SampleKS;
[default@SampleKS] get SampleCF where up = 'up' limit 3;
-------------------
RowKey: 150
=> (column=date, value=150, timestamp=1304937931)
=> (column=up, value=up, timestamp=1304937931)
-------------------
RowKey: 151
=> (column=date, value=151, timestamp=1304937932)
=> (column=up, value=up, timestamp=1304937932)
-------------------
RowKey: 152
=> (column=date, value=152, timestamp=1304937932)
=> (column=up, value=up, timestamp=1304937932)
3 Rows Returned.
{quote}
On the other hand, if you set limit to "1", you can reproduce the problem.
{quote}
[default@SampleKS] get SampleCF where up = 'up' and date > 150 limit 1;
0 Row Returned.
{quote}
There are two factors to cause this problem:
- 1. scanned first column doesn't match at specified clause like "date > 150".
- 2. "limit 1"
Only one factor doesn't cause problem. For example, I can get correct data
when I specify as following:
- "limit 1" -> "limit 2"
{quote}
[default@SampleKS] get SampleCF where up = 'up' and date > 150 limit 2;
-------------------
RowKey: 151
=> (column=date, value=151, timestamp=1304937932)
=> (column=up, value=up, timestamp=1304937932)
-------------------
RowKey: 152
=> (column=date, value=152, timestamp=1304937932)
=> (column=up, value=up, timestamp=1304937932)
2 Rows Returned.
{quote}
- "date > 150" -> "date >= 150"
{quote}
[default@SampleKS] get SampleCF where up = 'up' and date >= 150 limit 1;
-------------------
RowKey: 150
=> (column=date, value=150, timestamp=1304937931)
=> (column=up, value=up, timestamp=1304937931)
1 Row Returned.
{quote}
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