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https://issues.apache.org/jira/browse/CASSANDRA-8636?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jonathan Ellis resolved CASSANDRA-8636.
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Resolution: Cannot Reproduce
Fix Version/s: (was: 2.1.x)
Please reopen if you can reproduce on 3.0.x.
> Inconsistencies between two tables if BATCH used
> ------------------------------------------------
>
> Key: CASSANDRA-8636
> URL: https://issues.apache.org/jira/browse/CASSANDRA-8636
> Project: Cassandra
> Issue Type: Bug
> Environment: Cassandra 2.1.2, cqlengine 0.20.0, Debian Wheezy
> Reporter: mlowicki
>
> Two tables:
> * First one *entity* has log-like structure - whenever entity is modified we
> create new version of it and put into the table with new mtime which is part
> of compound key. Old one is removed.
> * Second one called *entity_by_id* is manually managed index for *entity*. By
> having only id you can get basic entity attributes from *entity_by_id*.
> While adding entity we do two inserts - to *entity* and *entity_by_id* (in
> this order)
> While deleting we do the same using the same order so first we remove record
> from entity table.
> It turned out that these two tables were inconsistent. We had ~260 records in
> *entity_by_id* for which there is no corresponding record in *entity*. In
> *entity* table it's much worse because ~7000 records in *entity_by_id* are
> missing and it was growing much faster.
> We were using LOCAL_QUROUM. Two datacenters. We didn't get any exceptions
> while inserts or deletes. BatchQuery from cqlengine has been used.
> if BatchQuery is not used:
> {code}
> with BatchQuery() as b:
> - entity.batch(b).save()
> - entity_by_id = EntityById.copy_fields_from(entity)
> - entity_by_id.batch(b).save()
> + entity.save()
> + entity_by_id = EntityById.copy_fields_from(entity)
> + entity_by_id.save()
> {code}
> Everything is fine. We don't have more inconsistencies. I've check what
> cqlengine generates and seems that works as expected:
> {code}
> ('BEGIN BATCH\n UPDATE sync.entity SET "name" = %(4)s WHERE "user_id" =
> %(0)s AND "data_type_id" = %(1)s AND "version" = %(2)s AND "id" = %(3)s\n
> INSERT INTO sync.entity_by_id ("user_id", "id", "parent_id", "deleted",
> "folder", "data_type_id", "version") VALUES (%(5)s, %(6)s, %(7)s, %(8)s,
> %(9)s, %(10)s, %(11)s)\nAPPLY BATCH;',)
> {code}
> Schemas:
> {code}
> CREATE TABLE entity (
> user_id text,
> data_type_id int,
> version bigint,
> id text,
> cache_guid text,
> client_defined_unique_tag text,
> ctime timestamp,
> deleted boolean,
> folder boolean,
> mtime timestamp,
> name text,
> originator_client_item_id text,
> parent_id text,
> position blob,
> server_defined_unique_tag text,
> specifics blob,
> PRIMARY KEY (user_id, data_type_id, version, id)
> ) WITH CLUSTERING ORDER BY (data_type_id ASC, version ASC, id ASC)
> AND bloom_filter_fp_chance = 0.01
> AND caching = '{"keys":"ALL", "rows_per_partition":"NONE"}'
> AND comment = ''
> AND compaction = {'min_threshold': '4', 'class':
> 'org.apache.cassandra.db.compaction.SizeTieredCompactionStrategy',
> 'max_threshold': '32'}
> AND compression = {'sstable_compression':
> 'org.apache.cassandra.io.compress.LZ4Compressor'}
> AND dclocal_read_repair_chance = 0.1
> AND default_time_to_live = 0
> AND gc_grace_seconds = 864000
> AND max_index_interval = 2048
> AND memtable_flush_period_in_ms = 0
> AND min_index_interval = 128
> AND read_repair_chance = 0.0
> AND speculative_retry = '99.0PERCENTILE';
> CREATE INDEX index_entity_parent_id ON sync.entity (parent_id);
> CREATE TABLE entity_by_id (
> user_id text,
> id text,
> cache_guid text,
> data_type_id int,
> deleted boolean,
> folder boolean,
> originator_client_item_id text,
> parent_id text,
> version bigint,
> PRIMARY KEY (user_id, id)
> ) WITH CLUSTERING ORDER BY (id ASC)
> AND bloom_filter_fp_chance = 0.01
> AND caching = '{"keys":"ALL", "rows_per_partition":"NONE"}'
> AND comment = ''
> AND compaction = {'min_threshold': '4', 'class':
> 'org.apache.cassandra.db.compaction.SizeTieredCompactionStrategy',
> 'max_threshold': '32'}
> AND compression = {'sstable_compression':
> 'org.apache.cassandra.io.compress.LZ4Compressor'}
> AND dclocal_read_repair_chance = 0.1
> AND default_time_to_live = 0
> AND gc_grace_seconds = 864000
> AND max_index_interval = 2048
> AND memtable_flush_period_in_ms = 0
> AND min_index_interval = 128
> AND read_repair_chance = 0.0
> AND speculative_retry = '99.0PERCENTILE';
> CREATE INDEX index_entity_by_id_parent_id ON entity_by_id (parent_id);
> {code}
> Previously we had many "batch size exceeded" warnings but limit is increased
> now as sometimes we put many KB of data into *specifics* blob field
> (*batch_size_warn_threshold_in_kb* is set now to 20).
> We had similar data model in other project where we have the same issue.
> There are not missing records in *entity* but couple of thousands in
> *entity_by_id*. I'll send more details on this soon.
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