[
https://issues.apache.org/jira/browse/CASSANDRA-12674?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Alex Petrov reassigned CASSANDRA-12674:
---------------------------------------
Assignee: (was: Alex Petrov)
> [SASI] Confusing AND/OR semantics for StandardAnalyzer
> -------------------------------------------------------
>
> Key: CASSANDRA-12674
> URL: https://issues.apache.org/jira/browse/CASSANDRA-12674
> Project: Cassandra
> Issue Type: Bug
> Components: Feature/SASI
> Environment: Cassandra 3.7
> Reporter: DuyHai Doan
> Priority: Normal
>
> {code:sql}
> Connected to Test Cluster at 127.0.0.1:9042.
> [cqlsh 5.0.1 | Cassandra 3.7 | CQL spec 3.4.2 | Native protocol v4]
> Use HELP for help.
> cqlsh> use test;
> cqlsh:test> CREATE TABLE sasi_bug(id int, clustering int, val text, PRIMARY
> KEY((id), clustering));
> cqlsh:test> CREATE CUSTOM INDEX ON sasi_bug(val) USING
> 'org.apache.cassandra.index.sasi.SASIIndex' WITH OPTIONS = {
> 'mode': 'CONTAINS',
> 'analyzer_class':
> 'org.apache.cassandra.index.sasi.analyzer.StandardAnalyzer',
> 'analyzed': 'true'};
> //1st example SAME PARTITION KEY
> cqlsh:test> INSERT INTO sasi_bug(id, clustering , val ) VALUES(1, 1,
> 'homeworker');
> cqlsh:test> INSERT INTO sasi_bug(id, clustering , val ) VALUES(1, 2,
> 'hardworker');
> cqlsh:test> SELECT * FROM sasi_bug WHERE val LIKE '%work home%';
> id | clustering | val
> ----+------------+------------
> 1 | 1 | homeworker
> 1 | 2 | hardworker
> (2 rows)
> //2nd example DIFFERENT PARTITION KEY
> cqlsh:test> INSERT INTO sasi_bug(id, clustering, val) VALUES(10, 1,
> 'speedrun');
> cqlsh:test> INSERT INTO sasi_bug(id, clustering, val) VALUES(11, 1,
> 'longrun');
> cqlsh:test> SELECT * FROM sasi_bug WHERE val LIKE '%long run%';
> id | clustering | val
> ----+------------+---------
> 11 | 1 | longrun
> (1 rows)
> {code}
> In the 1st example, both rows belong to the same partition so SASI returns
> both values. Indeed {{LIKE '%work home%'}} means {{contains 'work' OR
> 'home'}} so the result makes sense
> In the 2nd example, only one row is returned whereas we expect 2 rows because
> {{LIKE '%long run%'}} means {{contains 'long' OR 'run'}} so *speedrun* should
> be returned too.
> So where is the problem ? Explanation:
> When there is only 1 predicate, the root operation type is an *AND*:
> {code:java|title=QueryPlan}
> private Operation analyze()
> {
> try
> {
> Operation.Builder and = new Operation.Builder(OperationType.AND,
> controller);
> controller.getExpressions().forEach(and::add);
> return and.complete();
> }
> ...
> }
> {code}
> During the parsing of {{LIKE '%long run%'}}, SASI creates 2 expressions for
> the searched term: {{long}} and {{run}}, which corresponds to an *OR* logic.
> However, this piece of code just ruins the *OR* logic:
> {code:java|title=Operation}
> public Operation complete()
> {
> if (!expressions.isEmpty())
> {
> ListMultimap<ColumnDefinition, Expression>
> analyzedExpressions = analyzeGroup(controller, op, expressions);
> RangeIterator.Builder<Long, Token> range =
> controller.getIndexes(op, analyzedExpressions.values());
> ...
> }
> {code}
> As you can see, we blindly take all the *values* of the MultiMap (which
> contains a single entry for the {{val}} column with 2 expressions) and pass
> it to {{controller.getIndexes(...)}}
> {code:java|title=QueryController}
> public RangeIterator.Builder<Long, Token> getIndexes(OperationType op,
> Collection<Expression> expressions)
> {
> if (resources.containsKey(expressions))
> throw new IllegalArgumentException("Can't process the same
> expressions multiple times.");
> RangeIterator.Builder<Long, Token> builder = op == OperationType.OR
> ? RangeUnionIterator.<Long,
> Token>builder()
> :
> RangeIntersectionIterator.<Long, Token>builder();
> ...
> }
> {code}
> And because the root operation has *AND* type, the
> {{RangeIntersectionIterator}} will be used on both expressions {{long}} and
> {{run}}.
> So when data belong to different partitions, we have the *AND* logic that
> applies and eliminates _speedrun_
> When data belong to the same partition but different row, the
> {{RangeIntersectionIterator}} returns a single partition and then the rows
> are filtered further by {{operationTree.satisfiedBy}} and the results are
> correct
> {code:java|title=QueryPlan}
> while (currentKeys.hasNext())
> {
> DecoratedKey key = currentKeys.next();
> if (!keyRange.right.isMinimum() &&
> keyRange.right.compareTo(key) < 0)
> return endOfData();
> try (UnfilteredRowIterator partition =
> controller.getPartition(key, executionController))
> {
> Row staticRow = partition.staticRow();
> List<Unfiltered> clusters = new ArrayList<>();
> while (partition.hasNext())
> {
> Unfiltered row = partition.next();
> if (operationTree.satisfiedBy(row, staticRow,
> true))
> clusters.add(row);
> }
> ...
> }
> {code}
> /cc [~xedin] [~ifesdjeen]
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