[ https://issues.apache.org/jira/browse/CASSANDRA-13880?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16170260#comment-16170260 ]
Aleksey Yeschenko commented on CASSANDRA-13880: ----------------------------------------------- Branches with fixes: [3.0|https://github.com/iamaleksey/cassandra/commits/13880-3.0], [3.11|https://github.com/iamaleksey/cassandra/commits/13880-3.11], [4.0|https://github.com/iamaleksey/cassandra/commits/13880-4.0]. An isolated dtest [here|https://github.com/iamaleksey/cassandra-dtest/commits/13880]. The issue only triggers with a per partition limit set, doesn't with a regular limit. I am investigating why, but whatever the reason is, this fix is wanted/needed anyway - it does save us a pointless roundtrip in many scenarios. > Fix short read protection for tables with single columns PKs > ------------------------------------------------------------ > > Key: CASSANDRA-13880 > URL: https://issues.apache.org/jira/browse/CASSANDRA-13880 > Project: Cassandra > Issue Type: Bug > Components: Coordination > Reporter: Aleksey Yeschenko > Assignee: Aleksey Yeschenko > Priority: Critical > Fix For: 3.0.x, 3.11.x > > > CASSANDRA-12872 fixed counting replica rows, so that we do now fetch more > than one extra row if necessary. > Fixing the issue caused consistency_test.py:TestConsistency.test_13747 to > start failing, by exposing a bug in the way we handle empty clusterings. > When {{moreContents()}} asks for another row and {{lastClustering}} is > {{EMPTY}}, the response again (and again) contains the row with {{EMPTY}} > clustering. > SRP assumes it’s a new row, counts it as one, gets confused and keeps asking > for more, in a loop, again and again. > Arguably, a response to a read command with the following non-inclusive > {{ClusteringIndexFilter}}: > {code} > command.clusteringIndexFilter(partitionKey).forPaging(metadata.comparator, > Clustering.EMPTY, false); > {code} > ... should return nothing at all rather than a row with an empty clustering. > Also arguably, SRP should not even attempt to fetch more rows if > {{lastClustering == Clustering.EMPTY}}. In a partition key only column > we shouldn’t expect any more rows. > This JIRA is to fix the latter issue on SRP side - to modify SRP logic to > short-circuit execution if {{lastClustering}} was an {{EMPTY}} one instead of > querying pointlessly for non-existent extra rows. -- This message was sent by Atlassian JIRA (v6.4.14#64029) --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@cassandra.apache.org For additional commands, e-mail: commits-h...@cassandra.apache.org