cql - Cassandra sorting is not working -


i having cassandra table want data sorted according action_time field.

please find below script details.

    cassandra@cqlsh:activitylog> desc keyspace;cassandra@cqlsh:activitylog> desc keyspace;      create keyspace activitylog replication = {'class': 'simplestrategy', 'replication_factor': '3'}  , durable_writes = true;      create table activitylog.activity_log (         id timeuuid,         action_time timestamp,         vendor_id bigint,         primary key (id, action_time)     ) clustering order (action_time asc)         , bloom_filter_fp_chance = 0.01         , caching = '{"keys":"all", "rows_per_partition":"none"}'         , comment = ''         , compaction = {'min_threshold': '4', 'class': 'org.apache.cassandra.db.compaction.sizetieredcompactionstrategy', 'max_threshold': '32'}         , compression = {'sstable_compression': 'org.apache.cassandra.io.compress.lz4compressor'}         , dclocal_read_repair_chance = 0.1         , default_time_to_live = 0         , gc_grace_seconds = 864000         , max_index_interval = 2048         , memtable_flush_period_in_ms = 0         , min_index_interval = 128         , read_repair_chance = 0.0         , speculative_retry = '99.0percentile';      cassandra@cqlsh:activitylog> select id,action_time,vendor_id activity_log;       id                                   | action_time              | vendor_id     --------------------------------------+--------------------------+-----------      4ce8ea50-ea55-11e4-a220-4943c7dd5536 | 2015-04-24 13:11:18+0530 |      1234      4ce8ea53-ea55-11e4-a220-4943c7dd5536 | 2015-04-24 13:11:18+0530 |      1234      86aedb31-ea7f-11e4-aa45-4943c7dd5536 | 2015-04-24 18:13:34+0530 |      1234      09ec5340-ea55-11e4-a220-4943c7dd5536 | 2015-04-24 13:09:25+0530 |      1234      65e85a71-ea7f-11e4-aa45-4943c7dd5536 | 2015-04-24 18:12:39+0530 |      1234      65e85a72-ea7f-11e4-aa45-4943c7dd5536 | 2015-04-24 18:12:39+0530 |      1234      86aedb33-ea7f-11e4-aa45-4943c7dd5536 | 2015-04-24 18:13:34+0530 |      1234      4ce8ea52-ea55-11e4-a220-4943c7dd5536 | 2015-04-24 13:11:18+0530 |      1234      86aedb32-ea7f-11e4-aa45-4943c7dd5536 | 2015-04-24 18:13:34+0530 |      1234      09ec5341-ea55-11e4-a220-4943c7dd5536 | 2015-04-24 13:09:25+0530 |      1234      20935240-ea70-11e4-8fd7-4943c7dd5536 | 2015-04-24 16:23:20+0530 |      1234      65e85a73-ea7f-11e4-aa45-4943c7dd5536 | 2015-04-24 18:12:39+0530 |      1234      20935243-ea70-11e4-8fd7-4943c7dd5536 | 2015-04-24 16:23:20+0530 |      1234      86aedb30-ea7f-11e4-aa45-4943c7dd5536 | 2015-04-24 18:13:34+0530 |      1234      09ec5343-ea55-11e4-a220-4943c7dd5536 | 2015-04-24 13:09:25+0530 |      1234      20935241-ea70-11e4-8fd7-4943c7dd5536 | 2015-04-24 16:23:20+0530 |      1234      65e85a70-ea7f-11e4-aa45-4943c7dd5536 | 2015-04-24 18:12:39+0530 |      1234      20935242-ea70-11e4-8fd7-4943c7dd5536 | 2015-04-24 16:23:20+0530 |      1234      09ec5342-ea55-11e4-a220-4943c7dd5536 | 2015-04-24 13:09:25+0530 |      1234      4ce8ea51-ea55-11e4-a220-4943c7dd5536 | 2015-04-24 13:11:18+0530 |      1234       create keyspace activitylog replication = {'class': 'simplestrategy', 'replication_factor': '3'}  , durable_writes = true;      create table activitylog.activity_log (         id timeuuid,         action_time timestamp,         vendor_id bigint,         primary key (id, action_time)     ) clustering order (action_time asc)         , bloom_filter_fp_chance = 0.01         , caching = '{"keys":"all", "rows_per_partition":"none"}'         , comment = ''         , compaction = {'min_threshold': '4', 'class': 'org.apache.cassandra.db.compaction.sizetieredcompactionstrategy', 'max_threshold': '32'}         , compression = {'sstable_compression': 'org.apache.cassandra.io.compress.lz4compressor'}         , dclocal_read_repair_chance = 0.1         , default_time_to_live = 0         , gc_grace_seconds = 864000         , max_index_interval = 2048         , memtable_flush_period_in_ms = 0         , min_index_interval = 128         , read_repair_chance = 0.0         , speculative_retry = '99.0percentile';      cassandra@cqlsh:activitylog> select id,action_time,vendor_id activity_log;       id                                   | action_time              | vendor_id     --------------------------------------+--------------------------+-----------      4ce8ea50-ea55-11e4-a220-4943c7dd5536 | 2015-04-24 13:11:18+0530 |      1234      4ce8ea53-ea55-11e4-a220-4943c7dd5536 | 2015-04-24 13:11:18+0530 |      1234      86aedb31-ea7f-11e4-aa45-4943c7dd5536 | 2015-04-24 18:13:34+0530 |      1234      09ec5340-ea55-11e4-a220-4943c7dd5536 | 2015-04-24 13:09:25+0530 |      1234      65e85a71-ea7f-11e4-aa45-4943c7dd5536 | 2015-04-24 18:12:39+0530 |      1234      65e85a72-ea7f-11e4-aa45-4943c7dd5536 | 2015-04-24 18:12:39+0530 |      1234      86aedb33-ea7f-11e4-aa45-4943c7dd5536 | 2015-04-24 18:13:34+0530 |      1234      4ce8ea52-ea55-11e4-a220-4943c7dd5536 | 2015-04-24 13:11:18+0530 |      1234      86aedb32-ea7f-11e4-aa45-4943c7dd5536 | 2015-04-24 18:13:34+0530 |      1234      09ec5341-ea55-11e4-a220-4943c7dd5536 | 2015-04-24 13:09:25+0530 |      1234      20935240-ea70-11e4-8fd7-4943c7dd5536 | 2015-04-24 16:23:20+0530 |      1234      65e85a73-ea7f-11e4-aa45-4943c7dd5536 | 2015-04-24 18:12:39+0530 |      1234      20935243-ea70-11e4-8fd7-4943c7dd5536 | 2015-04-24 16:23:20+0530 |      1234      86aedb30-ea7f-11e4-aa45-4943c7dd5536 | 2015-04-24 18:13:34+0530 |      1234      09ec5343-ea55-11e4-a220-4943c7dd5536 | 2015-04-24 13:09:25+0530 |      1234      20935241-ea70-11e4-8fd7-4943c7dd5536 | 2015-04-24 16:23:20+0530 |      1234      65e85a70-ea7f-11e4-aa45-4943c7dd5536 | 2015-04-24 18:12:39+0530 |      1234      20935242-ea70-11e4-8fd7-4943c7dd5536 | 2015-04-24 16:23:20+0530 |      1234      09ec5342-ea55-11e4-a220-4943c7dd5536 | 2015-04-24 13:09:25+0530 |      1234      4ce8ea51-ea55-11e4-a220-4943c7dd5536 | 2015-04-24 13:11:18+0530 |      1234

as can see select statement not sorted per action_time column. while getting description of table showing data sorted action_time in asc order.

please me out.

it important note cassandra enforce sorting order only within partition key. in case, partition key id, , table definition indicates rows similar partition keys ordered clustering key action_time.

your problem not sort order not work. cardinality of partition key high cassandra doesn't have sort.

this becomes clear when model data lower-cardinality partition key. watch happens when re-create table activity_log_by_vendor re-ordered primary key: 

create table activity_log_by_vendor (     id timeuuid,     action_time timestamp,     vendor_id bigint,     primary key (vendor_id, action_time, id));  aploetz@cqlsh:stackoverflow2> select * activity_log_by_vendor vendor_id = 1234;   vendor_id | action_time              | id -----------+--------------------------+--------------------------------------       1234 | 2015-04-24 02:39:25-0500 | 09ec5340-ea55-11e4-a220-4943c7dd5536       1234 | 2015-04-24 02:39:25-0500 | 09ec5341-ea55-11e4-a220-4943c7dd5536       1234 | 2015-04-24 02:39:25-0500 | 09ec5342-ea55-11e4-a220-4943c7dd5536       1234 | 2015-04-24 02:39:25-0500 | 09ec5343-ea55-11e4-a220-4943c7dd5536       1234 | 2015-04-24 02:41:18-0500 | 4ce8ea50-ea55-11e4-a220-4943c7dd5536       1234 | 2015-04-24 02:41:18-0500 | 4ce8ea51-ea55-11e4-a220-4943c7dd5536       1234 | 2015-04-24 02:41:18-0500 | 4ce8ea52-ea55-11e4-a220-4943c7dd5536       1234 | 2015-04-24 02:41:18-0500 | 4ce8ea53-ea55-11e4-a220-4943c7dd5536       1234 | 2015-04-24 05:53:20-0500 | 20935240-ea70-11e4-8fd7-4943c7dd5536       1234 | 2015-04-24 05:53:20-0500 | 20935241-ea70-11e4-8fd7-4943c7dd5536       1234 | 2015-04-24 05:53:20-0500 | 20935242-ea70-11e4-8fd7-4943c7dd5536       1234 | 2015-04-24 05:53:20-0500 | 20935243-ea70-11e4-8fd7-4943c7dd5536       1234 | 2015-04-24 07:42:39-0500 | 65e85a70-ea7f-11e4-aa45-4943c7dd5536       1234 | 2015-04-24 07:42:39-0500 | 65e85a71-ea7f-11e4-aa45-4943c7dd5536       1234 | 2015-04-24 07:42:39-0500 | 65e85a72-ea7f-11e4-aa45-4943c7dd5536       1234 | 2015-04-24 07:42:39-0500 | 65e85a73-ea7f-11e4-aa45-4943c7dd5536       1234 | 2015-04-24 07:43:34-0500 | 86aedb30-ea7f-11e4-aa45-4943c7dd5536       1234 | 2015-04-24 07:43:34-0500 | 86aedb31-ea7f-11e4-aa45-4943c7dd5536       1234 | 2015-04-24 07:43:34-0500 | 86aedb32-ea7f-11e4-aa45-4943c7dd5536       1234 | 2015-04-24 07:43:34-0500 | 86aedb33-ea7f-11e4-aa45-4943c7dd5536  (20 rows)

by partitioning on vendor_id, cassandra has 20 cql rows sort. , since have same vendor_id, cassandra enforce sort order on action_time , id, descending (note, added id primary key ensure uniqueness).

last month wrote article planetcassandra describing behavior: we shall have order!

datastax's patrick mcfadin has article great job discussing how model these types of problems: getting started time series data modeling.

give 2 articles read, , should better understanding of how leverage cassandra clustering order.


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