[CASSANDRA-15169] SASI does not compare strings correctly

• Type: Bug
• Status: Resolved
• Priority: Normal
• Resolution: Fixed
• Fix Version/s: 3.11.5, 4.0-alpha
• Component/s: Feature/SASI
• Bug Category: Correctness - API / Semantic Implementation
• Severity: Normal
• Complexity: Normal
• Discovered By: User Report
• Platform: All
• Since Version: 3.4

Source Control Link

https://github.com/apache/cassandra/commit/b20daee68d96cca7e23f5c2e83f687ba2f3b1852

Test and Documentation Plan

unit test

• Assignee: mazhenlin
• Reporter: mazhenlin

Authors

mazhenlin

Reviewers

Michael Semb Wever

• Created: 18/Jun/19 15:58
• Updated: 17/Oct/19 06:11
• Resolved: 17/Oct/19 06:11

Description

In our scenario, we need to query with '>' conditions on string columns. So I created index with  is_literal = false. like the following:

 

CREATE TABLE test (id int primary key, t text);

CREATE CUSTOM INDEX ON test (t) USING 'org.apache.cassandra.index.sasi.SASIIndex' WITH OPTIONS = {'is_literal': 'false'};

 I also inserted some records and query:

 

insert into test(id,t) values(1,'abc');
select * from test where t > 'ab';

At first ,it worked. But after flush, the query returned none record.

I have read the code of SASIIndex and found that it is because in the 

Expression.isLowerSatisfiedBy

function,

term.compareTo

was called with parameter checkFully=false, which cause the string 'abc' was only compared with its first 2 characters( length of expression value).

 

I have wrote a UT for this case and fixed it.