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https://issues.apache.org/jira/browse/CASSANDRA-5540?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13650762#comment-13650762
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Sam Tunnicliffe commented on CASSANDRA-5540:
--------------------------------------------
I don't think this is caused by the index updates in KeysSearcher. There, we
only compare the values & since this test always writes the same values the
index entry is never deemed stale, and so we don't ever write a tombstone.
The test script does reproduce the issue completely reliably though, so I'll
dig in and find the actual cause.
> Concurrent secondary index updates remove rows from the index
> -------------------------------------------------------------
>
> Key: CASSANDRA-5540
> URL: https://issues.apache.org/jira/browse/CASSANDRA-5540
> Project: Cassandra
> Issue Type: Bug
> Affects Versions: 1.2.4
> Reporter: Alexei Bakanov
>
> Existing rows disappear from secondary index when doing simultaneous updates
> of a row with the same secondary index value.
> Here is a little pycassa script that reproduces a bug. The script inserts 4
> rows with same secondary index value, reads those rows back and check that
> there are 4 of them.
> Please run two instances of the script simultaneously in two separate
> terminals in order to simulate concurrent updates:
> {code}
> -----scrpit.py START-----
> import pycassa
> from pycassa.index import *
> pool = pycassa.ConnectionPool('ks123')
> cf = pycassa.ColumnFamily(pool, 'cf1')
> while True:
> for rowKey in xrange(4):
> cf.insert(str(rowKey), {'indexedColumn': 'indexedValue'})
> index_expression = create_index_expression('indexedColumn',
> 'indexedValue')
> index_clause = create_index_clause([index_expression])
> rows = cf.get_indexed_slices(index_clause)
> length = len(list(rows))
> if length == 4:
> pass
> else:
> print 'found just %d rows out of 4' % length
> pool.dispose()
> ---script.py FINISH---
> ---schema cli start---
> create keyspace ks123
> with placement_strategy = 'NetworkTopologyStrategy'
> and strategy_options = {datacenter1 : 1}
> and durable_writes = true;
> use ks123;
> create column family cf1
> with column_type = 'Standard'
> and comparator = 'AsciiType'
> and default_validation_class = 'AsciiType'
> and key_validation_class = 'AsciiType'
> and read_repair_chance = 0.1
> and dclocal_read_repair_chance = 0.0
> and populate_io_cache_on_flush = false
> and gc_grace = 864000
> and min_compaction_threshold = 4
> and max_compaction_threshold = 32
> and replicate_on_write = true
> and compaction_strategy =
> 'org.apache.cassandra.db.compaction.SizeTieredCompactionStrategy'
> and caching = 'KEYS_ONLY'
> and column_metadata = [
> {column_name : 'indexedColumn',
> validation_class : AsciiType,
> index_name : 'INDEX1',
> index_type : 0}]
> and compression_options = {'sstable_compression' :
> 'org.apache.cassandra.io.compress.SnappyCompressor'};
> ---schema cli finish---
> {code}
> Test cluster created with 'ccm create --cassandra-version 1.2.4 --nodes 1
> --start testUpdate'
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