[CASSANDRA-7575] Custom 2i validation

• Type: Improvement
• Status: Resolved
• Priority: Low
• Resolution: Fixed
• Fix Version/s: 2.1.1
• Component/s: Legacy/CQL
• Labels: 2i cql3 secondaryIndex secondary_index select
• Assignee: Andres de la Peña Assign to me
• Reporter: Andres de la Peña

Authors

Andres de la Peña

Reviewers

Sergio Bossa

• Created: 19/Jul/14 16:36
• Updated: 16/Apr/19 12:31
• Resolved: 04/Aug/14 16:34

Description

There are several projects using custom secondary indexes as an extension point to integrate C* with other systems such as Solr or Lucene. The usual approach is to embed third party indexing queries in CQL clauses.

For example, DSE Search embeds Solr syntax this way:

SELECT title FROM solr WHERE solr_query='title:natio*';

Stratio platform embeds custom JSON syntax for searching in Lucene indexes:

SELECT * FROM tweets WHERE lucene='{
    filter : {
        type: "range",
        field: "time",
        lower: "2014/04/25",
        upper: "2014/04/1"
    },
    query  : {
        type: "phrase", 
        field: "body", 
        values: ["big", "data"]
    },
    sort  : {fields: [ {field:"time", reverse:true} ] }
}';

Tuplejump Stargate also uses the Stratio's open source JSON syntax:

SELECT name,company FROM PERSON WHERE stargate ='{
    filter: {
        type: "range",
        field: "company",
        lower: "a",
        upper: "p"
    },
    sort:{
       fields: [{field:"name",reverse:true}]
    }
}';

These syntaxes are validated by the corresponding 2i implementation. This validation is done behind the StorageProxy command distribution. So, far as I know, there is no way to give rich feedback about syntax errors to CQL users.

I'm uploading a patch with some changes trying to improve this. I propose adding an empty validation method to SecondaryIndexSearcher that can be overridden by custom 2i implementations:

public void validate(List<IndexExpression> clause) {}

And call it from SelectStatement#getRangeCommand:

ColumnFamilyStore cfs = Keyspace.open(keyspace()).getColumnFamilyStore(columnFamily());
        for (SecondaryIndexSearcher searcher : cfs.indexManager.getIndexSearchersForQuery(expressions))
        {

            try
            {
                searcher.validate(expressions);
            }
            catch (RuntimeException e)
            {
                String exceptionMessage = e.getMessage();
                if (exceptionMessage != null 
                        && !exceptionMessage.trim().isEmpty())
                    throw new InvalidRequestException(
                            "Invalid index expression: " + e.getMessage());
                else
                    throw new InvalidRequestException(
                            "Invalid index expression");
            }
        }

In this way C* allows custom 2i implementations to give feedback about syntax errors.

We are currently using these changes in a fork with no problems.

Issue Links

• is duplicated by: CASSANDRA-7574 Support Custom Predicate in CQL SELECT for Custom Secondary Index