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https://issues.apache.org/jira/browse/CASSANDRA-7575?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14074678#comment-14074678
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Robert Stupp commented on CASSANDRA-7575:
-----------------------------------------
The custom column solution is a bit dirty by that you query column 'foo' for
something that is in column 'bar'.
I think we can add support for 2i in UDFs (as an extension to UDFs - not with
the basics covered by CASSANDRA-7395) - maybe by providing some information
like table/row/column meta data to the UDF information.
UDFs could also help to cover "complex" queries against
lucene/solr/elasticsearch (conditional filter/query against multiple fields,
highlighting, etc). For example with something like this to get every row with
a full-text-search score > .75. But that's stuff for a separate ticket - the
UDF impl would then return a set of primary keys - so it's a "query rewrite"
behind the scenes. But the syntax is much more obvious.
{noformat}
SELECT * FROM my_super_table WHERE elasticsearch('{
filter: {
type: "range",
field: "company",
lower: "a",
upper: "p"
},
sort:{
fields: [{field:"name",reverse:true}]
}
}') > 0.75
{noformat}
> Custom 2i validation
> --------------------
>
> Key: CASSANDRA-7575
> URL: https://issues.apache.org/jira/browse/CASSANDRA-7575
> Project: Cassandra
> Issue Type: Improvement
> Components: API
> Reporter: Andrés de la Peña
> Assignee: Andrés de la Peña
> Priority: Minor
> Labels: 2i, cql3, secondaryIndex, secondary_index, select
> Attachments: 2i_validation.patch
>
>
> 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|http://www.datastax.com/what-we-offer/products-services/datastax-enterprise]
> embeds Solr syntax this way:
> {code}
> SELECT title FROM solr WHERE solr_query='title:natio*';
> {code}
> [Stratio platform|https://github.com/Stratio/stratio-cassandra] embeds custom
> JSON syntax for searching in Lucene indexes:
> {code}
> 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} ] }
> }';
> {code}
> Tuplejump [Stargate|http://tuplejump.github.io/stargate/] also uses the
> Stratio's open source JSON syntax:
> {code}
> SELECT name,company FROM PERSON WHERE stargate ='{
> filter: {
> type: "range",
> field: "company",
> lower: "a",
> upper: "p"
> },
> sort:{
> fields: [{field:"name",reverse:true}]
> }
> }';
> {code}
> 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:
> {code}
> public void validate(List<IndexExpression> clause) {}
> {code}
> And call it from SelectStatement#getRangeCommand:
> {code}
> 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");
> }
> }
> {code}
> 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.
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