I'm having some trouble getting a configuration script to match up with the columnfamily names I'm using. I feel like it would be a helpful debugging tool to be able to log all of the currently configured column families.
Is this possible? I've been looking around google groups and haven't found any mention of such a thing.
To display all of the keyspaces and their respective column families you can use nodetool cfstats
It will a very long list:
lyubent:bin lyubentodorov$ ./nodetool cfstats
Keyspace: system_traces <-------- KS
Read Count: 0
Read Latency: NaN ms.
Write Count: 0
Write Latency: NaN ms.
Pending Tasks: 0
Column Family: sessions <-------- CF
SSTable count: 0
Space used (live): 0
Space used (total): 0
...
Column Family: events <-------- CF
SSTable count: 0
Space used (live): 0
Space used (total): 0
Number of Keys (estimate): 0
Memtable Columns Count: 0
...ETC....
#Slater Tyranus
For CQL3 tables
>echo "describe keyspace <your_keyspace_name>;" > command.cql
>cqlsh -3 -f command.cql > /tmp/schema.txt
For Thrift column families
>echo "describe keyspace <your_keyspace_name>;" > command.txt
>cassandra-cli -f command.txt > /tmp/schema.txt
Related
When I query secondary index with pagination, query becomes slower when data grows.
I thought with pagination, no matter how large your data grow, it takes same time to query one page. Is that true? Why my query get slower?
My simplified table is
CREATE TABLE closed_executions (
domain_id uuid,
workflow_id text,
start_time timestamp,
workflow_type_name text,
PRIMARY KEY ((domain_id), start_time)
) WITH CLUSTERING ORDER BY (start_time DESC)
AND COMPACTION = {
'class': 'org.apache.cassandra.db.compaction.LeveledCompactionStrategy'
}
AND GC_GRACE_SECONDS = 172800;
And I create a secondary index as
CREATE INDEX closed_by_type ON closed_executions (workflow_type_name);
I query with following CQL
SELECT workflow_id, start_time, workflow_type_name
FROM closed_executions
WHERE domain_id = ?
AND start_time >= ?
AND start_time <= ?
AND workflow_type_name = ?
and code
query := v.session.Query(templateGetClosedWorkflowExecutionsByType,
request.DomainUUID,
common.UnixNanoToCQLTimestamp(request.EarliestStartTime),
common.UnixNanoToCQLTimestamp(request.LatestStartTime),
request.WorkflowTypeName).Consistency(gocql.One)
iter := query.PageSize(request.PageSize).PageState(request.NextPageToken).Iter()
// PageSize is 10, but could be thousand
Environement:
MacBook Pro
Cassandra: 3.11.0
GoCql: github.com/gocql/gocql master
Observation:
10K rows, within second
100K rows, ~3 second
1M rows, ~17 second
Debug log:
INFO [ScheduledTasks:1] 2018-09-11 16:29:48,349 NoSpamLogger.java:91 - Some operations were slow, details available at debug level (debug.log)
DEBUG [ScheduledTasks:1] 2018-09-11 16:29:48,357 MonitoringTask.java:173 - 1 operations were slow in the last 5005 msecs:
<SELECT * FROM cadence_visibility.closed_executions WHERE workflow_type_name = code.uber.internal/devexp/cadence-bench/load/basic.stressWorkflowExecute AND token(domain_id, domain_partition) >= token(d3138e78-abe7-48a0-adb9-8c466a9bb3fa, 0) AND token(domain_id, domain_partition) <= token(d3138e78-abe7-48a0-adb9-8c466a9bb3fa, 0) AND start_time >= 2018-09-11 16:29-0700 AND start_time <= 1969-12-31 16:00-0800 LIMIT 10>, time 2747 msec - slow timeout 500 msec
DEBUG [COMMIT-LOG-ALLOCATOR] 2018-09-11 16:31:47,774 AbstractCommitLogSegmentManager.java:107 - No segments in reserve; creating a fresh one
DEBUG [ScheduledTasks:1] 2018-09-11 16:40:22,922 ColumnFamilyStore.java:899 - Enqueuing flush of size_estimates: 23.997MiB (2%) on-heap, 0.000KiB (0%) off-heap
Related ref (no answer for my questions):
https://lists.apache.org/thread.html/%3CCAAiKoBidknHVOz8oQQmncZFZHdFiDfW6HTs63vxXCOhisQYZgg#mail.gmail.com%3E
https://www.datastax.com/dev/blog/cassandra-native-secondary-index-deep-dive
https://docs.datastax.com/en/developer/java-driver/3.2/manual/paging/
-- Edit
tablestats returns
Total number of tables: 105
----------------
Keyspace : cadence_visibility
Read Count: 19
Read Latency: 0.5125263157894736 ms.
Write Count: 3220964
Write Latency: 0.04900822269357869 ms.
Pending Flushes: 0
Table: closed_executions
SSTable count: 1
SSTables in each level: [1, 0, 0, 0, 0, 0, 0, 0, 0]
Space used (live): 20.3 MiB
Space used (total): 20.3 MiB
Space used by snapshots (total): 0 bytes
Off heap memory used (total): 6.35 KiB
SSTable Compression Ratio: 0.40192660515179696
Number of keys (estimate): 3
Memtable cell count: 28667
Memtable data size: 7.35 MiB
Memtable off heap memory used: 0 bytes
Memtable switch count: 9
Local read count: 9
Local read latency: NaN ms
Local write count: 327024
Local write latency: NaN ms
Pending flushes: 0
Percent repaired: 0.0
Bloom filter false positives: 0
Bloom filter false ratio: 0.00000
Bloom filter space used: 16 bytes
Bloom filter off heap memory used: 8 bytes
Index summary off heap memory used: 38 bytes
Compression metadata off heap memory used: 6.3 KiB
Compacted partition minimum bytes: 150
Compacted partition maximum bytes: 62479625
Compacted partition mean bytes: 31239902
Average live cells per slice (last five minutes): NaN
Maximum live cells per slice (last five minutes): 0
Average tombstones per slice (last five minutes): NaN
Maximum tombstones per slice (last five minutes): 0
Dropped Mutations: 0 bytes
----------------
Why pagination doesn't scale as the main table?
Your data in your secondary index is disperse
pagination will only apply logic
until it hits the page number
since your data is not clustered by time
you still have to sift through lots and lots of rows
before you can find your first 10 for example .
Query Tracing do show pagination plays at the very late phase.
Why secondary index is slow?
First Cassandra reads the index table to retrieve the primary key of all matching rows and for each of them, it will read the original table to fetch out the data. It is known anti-patterns with low cardinality index. (reference https://www.datastax.com/dev/blog/cassandra-native-secondary-index-deep-dive)
I'm working on a single Cassandra 3.11.2 node(RHEL 6.5). In keyspace(named 'test'), I've a table named 'test'. I entered some rows via cqlsh and then did nodetool flush. I checked in the data directory to confirm that a SSTable got created. Now I deleted all the .db files(from the test.test data directory using rm *.db).
Strangely, I can still see all the rows in cqlsh! I don't understand, how this is happening since I manually deleted the SSTable.
Given below is my keyspace:
CREATE KEYSPACE test WITH replication = {'class': 'SimpleStrategy', 'replication_factor': '1'} AND durable_writes = true;
Given below is the table:
CREATE TABLE test.test (
aadhar_number int PRIMARY KEY,
address text,
name text
) WITH bloom_filter_fp_chance = 0.01
AND caching = {'keys': 'ALL', 'rows_per_partition': 'NONE'}
AND comment = ''
AND compaction = {'class': 'org.apache.cassandra.db.compaction.SizeTieredCompactionStrategy', 'max_threshold': '32', 'min_threshold': '4'}
AND compression = {'chunk_length_in_kb': '64', 'class': 'org.apache.cassandra.io.compress.LZ4Compressor'}
AND crc_check_chance = 1.0
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 = '99PERCENTILE';
Given below is the output of nodetool tablestats command(after I had deleted the SSTable):
Keyspace : test
Read Count: 0
Read Latency: NaN ms
Write Count: 13
Write Latency: 0.11269230769230769 ms
Pending Flushes: 0
Table: test
SSTable count: 1
Space used (live): 5220
Space used (total): 5220
Space used by snapshots (total): 0
Off heap memory used (total): 48
SSTable Compression Ratio: 0.7974683544303798
Number of partitions (estimate): 255
Memtable cell count: 0
Memtable data size: 0
Memtable off heap memory used: 0
Memtable switch count: 4
Local read count: 0
Local read latency: NaN ms
Local write count: 10
Local write latency: NaN ms
Pending flushes: 0
Percent repaired: 0.0
Bloom filter false positives: 0
Bloom filter false ratio: 0.00000
Bloom filter space used: 24
Bloom filter off heap memory used: 16
Index summary off heap memory used: 16
Compression metadata off heap memory used: 16
Compacted partition minimum bytes: 18
Compacted partition maximum bytes: 50
Compacted partition mean bytes: 36
Average live cells per slice (last five minutes): 5.0
Maximum live cells per slice (last five minutes): 5
Average tombstones per slice (last five minutes): 1.0
Maximum tombstones per slice (last five minutes): 1
Dropped Mutations: 0
I restarted Cassandra and only then the data stopped showing in cqlsh.
A very good article for understanding filesystem details in linux.
On linux, filenames are just pointers (inodes) that point to the memory where the file resides. When Cassandra open the files, it holds a link to it. When you use rm to remove the file, you delete the link from the filesystem to the physical memory, but the file is still referenced by a live process and is therefore not deleted. You can easily check that with the command lsof (list open files). There is a flag to list for a given pid (check the cassandra pid with something like ps aux | grep cassandra)
Obviously, when you restart Cassandra, the file get deleted.
I have create a keyspace and table within it for documents store.
The code I used is
CREATE KEYSPACE space WITH replication = {'class':'SimpleStrategy', 'replication_factor' : 3};
USE space;
CREATE TABLE documents (
doc_id text,
path text,
content text,
metadata_id text,
PRIMARY KEY (doc_id)
)
WITH compression = { 'sstable_compression' : 'LZ4Compressor' };
Then I've pushed some data into it and with using a command nodetool cfstats orpd.documents I wanted to check compression ratio.
$ nodetool cfstats space.documents
Keyspace: space
Read Count: 0
Read Latency: NaN ms.
Write Count: 2005
Write Latency: 0.050547132169576056 ms.
Pending Flushes: 0
Table: documents
SSTable count: 0
Space used (live): 0
Space used (total): 0
Space used by snapshots (total): 0
Off heap memory used (total): 0
SSTable Compression Ratio: 0.0
Number of keys (estimate): 978
Memtable cell count: 8020
Memtable data size: 92999622
Memtable off heap memory used: 0
Memtable switch count: 0
Local read count: 0
Local read latency: NaN ms
Local write count: 2005
Local write latency: 0.051 ms
Pending flushes: 0
Bloom filter false positives: 0
Bloom filter false ratio: 0.00000
Bloom filter space used: 0
Bloom filter off heap memory used: 0
Index summary off heap memory used: 0
Compression metadata off heap memory used: 0
Compacted partition minimum bytes: 0
Compacted partition maximum bytes: 0
Compacted partition mean bytes: 0
Average live cells per slice (last five minutes): 0.0
Maximum live cells per slice (last five minutes): 0.0
Average tombstones per slice (last five minutes): 0.0
Maximum tombstones per slice (last five minutes): 0.0
----------------
However, I got confused because the ratio is 0.0, even though I use a compressor.
I am curious whether more data needs to be put into DB in order to get the measure or I am doing somethig wrong.
Your all data is in memtable
Run the below command to flush your memtable data to sstable
nodetool flush
We have a cluster with 7 nodes and we use the datastax java driver to connect to the cluster. The problem is that I am getting constant NoHostAvailableException like this:
Caused by:
com.datastax.driver.core.exceptions.NoHostAvailableException: All
host(s) tried for query failed (tried: /172.31.7.243:9042
(com.datastax.driver.core.exceptions.DriverException: Timeout while
trying to acquire available connection (you may want to increase the
driver number of per-host connections)), /172.31.7.245:9042
(com.datastax.driver.core.exceptions.DriverException: Timeout while
trying to acquire available connection (you may want to increase the
driver number of per-host connections)), /172.31.7.246:9042
(com.datastax.driver.core.exceptions.DriverException: Timeout while
trying to acquire available connection (you may want to increase the
driver number of per-host connections)), /172.31.7.247:9042,
/172.31.7.232:9042, /172.31.7.233:9042, /172.31.7.244:9042 [only
showing errors of first 3 hosts, use getErrors() for more details])
All the nodes are up:
UN 172.31.7.244 152.21 GB 256 14.5% 58abea69-e7ba-4e57-9609-24f3673a7e58 RAC1
UN 172.31.7.245 168.4 GB 256 14.5% bc11b4f0-cf96-4ca5-9a3e-33cc2b92a752 RAC1
UN 172.31.7.246 177.71 GB 256 13.7% 8dc7bb3d-38f7-49b9-b8db-a622cc80346c RAC1
UN 172.31.7.247 158.57 GB 256 14.1% 94022081-a563-4042-81ab-75ffe4d13194 RAC1
UN 172.31.7.243 176.83 GB 256 14.6% 0dda3410-db58-42f2-9351-068bdf68f530 RAC1
UN 172.31.7.233 159 GB 256 13.6% 01e013fb-2f57-44fb-b3c5-fd89d705bfdd RAC1
UN 172.31.7.232 166.05 GB 256 15.0% 4d009603-faa9-4add-b3a2-fe24ec16a7c1 RAC1
but two of them have high cpu load, especially the 232 because I am running a lot of deletes using cqlsh in that node.
I know that deletes generate tombstones, but with 7 nodes in the cluster I do not think is normal that all the host are not accesible.
Our configuration for the java connection is:
com.datastax.driver.core.Cluster cluster = null;
//Get contact points
String[] contactPoints=this.environment.getRequiredProperty(CASSANDRA_CLUSTER_URL).split(",");
cluster = com.datastax.driver.core.Cluster.builder()
.addContactPoints(contactPoints))
.withCredentials(this.environment.getRequiredProperty(CASSANDRA_CLUSTER_USERNAME),
this.environment.getRequiredProperty(CASSANDRA_CLUSTER_PASSWORD))
.withQueryOptions(new QueryOptions()
.setConsistencyLevel(ConsistencyLevel.QUORUM))
.withLoadBalancingPolicy(new TokenAwarePolicy(new RoundRobinPolicy()))
.withRetryPolicy(new LoggingRetryPolicy(DowngradingConsistencyRetryPolicy.INSTANCE))
.withPort(Integer.parseInt(this.environment.getRequiredProperty(CASSANDRA_CLUSTER_PORT)))
.build();
Metadata metadata = cluster.getMetadata();
for ( Host host : metadata.getAllHosts() ) {
LOG.info("Datacenter: "+host.getDatacenter()+"; Host: "+host.getAddress()+"; DC: "+host.getDatacenter()+"\n");
}
and the contact points are:
172.31.7.244,172.31.7.243,172.31.7.245,172.31.7.246,172.31.7.247
Anyone knows how I can solve this problem? Or at least have anyone some hint about how to deal with this situation?
Update: If I get the error messages withe.getErrors() I obtain:
/172.31.7.243:9042=com.datastax.driver.core.OperationTimedOutException: [/172.31.7.243:9042] Operation timed out,
/172.31.7.244:9042=com.datastax.driver.core.OperationTimedOutException: [/172.31.7.244:9042] Operation timed out,
/172.31.7.245:9042=com.datastax.driver.core.OperationTimedOutException: [/172.31.7.245:9042] Operation timed out,
/172.31.7.246:9042=com.datastax.driver.core.OperationTimedOutException: [/172.31.7.246:9042] Operation timed out,
/172.31.7.247:9042=com.datastax.driver.core.OperationTimedOutException: [/172.31.7.247:9042] Operation timed out}
UPDATE:
The replication factor of the keyspace is 3.
For the deletes Im running them using different files with the cql queries:
cqlsh ip_node_1 -f script-1.duplicates
cqlsh ip_node_1 -f script-2.duplicates
cqlsh ip_node_1 -f script-3.duplicates
...
I am not specifying any consistency level, so is using the default one which is ONE.
Each of the previous files contain deletes like this:
DELETE FROM keyspace_name.search WHERE idline1 = 837 and idline2 = 841 and partid = 8558 and id = 18c04c20-8a3a-11e5-9e20-0025905a2ab2;
And the column family is:
CREATE TABLE search (
idline1 bigint,
idline2 bigint,
partid int,
id uuid,
field3 int,
field4 int,
field5 int,
field6 int,
field7 int,
field8 int,
field9 double,
field10 bigint,
field11 bigint,
field12 bigint,
field13 boolean,
field14 boolean,
field15 int,
field16 bigint,
field17 int,
field18 int,
field19 int,
field20 int,
field21 uuid,
field22 boolean,
PRIMARY KEY ((idline1, idline2, partid), id)
) WITH
bloom_filter_fp_chance=0.010000 AND
caching='KEYS_ONLY' AND
comment='Table with the snp between lines' AND
dclocal_read_repair_chance=0.000000 AND
gc_grace_seconds=0 AND
index_interval=128 AND
read_repair_chance=0.100000 AND
replicate_on_write='true' AND
populate_io_cache_on_flush='false' AND
default_time_to_live=0 AND
speculative_retry='99.0PERCENTILE' AND
memtable_flush_period_in_ms=0 AND
compaction={'class': 'SizeTieredCompactionStrategy'} AND
compression={'sstable_compression': 'LZ4Compressor'};
CREATE INDEX search_partid ON search (partid);
CREATE INDEX search_field8 ON search (field8);
UPDATE (18-03-2016):
After the deletes start to be executed I found the cpu of some of the nodes increases a lot:
I check the processes on that nodes and only cassandra is running but consuming a lot of cpu. The rest of the nodes are not using almost cpu.
UPDATE (04-04-2016): I do not know if it is related. I check the nodes which a lot of CPU (near 96%) and th gc activity remains on 1.6% (using only 3 GB from the 10 which have assigned).
Checing the thread pool stats:
nodetool tpstats
Pool Name Active Pending Completed Blocked All time blocked
ReadStage 0 0 20042001 0 0
RequestResponseStage 0 0 149365845 0 0
MutationStage 32 117720 181498576 0 0
ReadRepairStage 0 0 799373 0 0
ReplicateOnWriteStage 0 0 13624173 0 0
GossipStage 0 0 5580503 0 0
CacheCleanupExecutor 0 0 0 0 0
AntiEntropyStage 0 0 32173 0 0
MigrationStage 0 0 9 0 0
MemtablePostFlusher 0 0 45044 0 0
MemoryMeter 0 0 9553 0 0
FlushWriter 0 0 9425 0 18
ValidationExecutor 0 0 15980 0 0
MiscStage 0 0 0 0 0
PendingRangeCalculator 0 0 7 0 0
CompactionExecutor 0 0 1293147 0 0
commitlog_archiver 0 0 0 0 0
InternalResponseStage 0 0 0 0 0
HintedHandoff 0 0 273 0 0
Message type Dropped
RANGE_SLICE 0
READ_REPAIR 0
PAGED_RANGE 0
BINARY 0
READ 0
MUTATION 0
_TRACE 0
REQUEST_RESPONSE 0
COUNTER_MUTATION 0
I realize that the pending mutation stages are growing but the active value remain the same, could be this the problem?
I see two problems with your datamodel.
You use two secondary indexes. One is on a field on the partition key. I don't know how cassandra behaves in this case. Worst case is, that even if you use the complete partition key (like you do in your example delete) cassandra does a lookup in the secondary index. In that case this would mean a full cluster scan, because secondary indexes are only stored per partition. Since only a part of the partition key is indexed cassandra does not know on which partition the index informations lies. This behavior at least would explain the timeouts.
You said, you delete a lot of rows in a specific partition. That is also a problem. For each deletion cassandra creates a tombstone. The more tombstones there are, the slower the read will become. This will sooner or later lead to timeouts or exceptions (I believe cassandra will write warnings when 1000 tombstones are reached and throw exceptions when 10.000 tombstones are reached). Btw. these tombstones are also created in the secondary index. By default cassandra will remove tombstones after gc_grace_seconds (by default 10 days) when a compaction is performed. You could change this property per table. More information on these table properties can be found here: Table Properties
I believe the first point could be the reason for the timeouts.
I have CF with 1280 rows.
Each row has 6 columns. Im trying to $cf->get_range('pq_questions','','',1200) and it gets all rows but too slow(about 4-6 sec)
Column Family: pq_questions
SSTable count: 1
Space used (live): 668363
Space used (total): 668363
Number of Keys (estimate): 1280
Memtable Columns Count: 0
Memtable Data Size: 0
Memtable Switch Count: 0
Read Count: 0
Read Latency: NaN ms.
Write Count: 0
Write Latency: NaN ms.
Pending Tasks: 0
Key cache capacity: 200000
Key cache size: 1000
Key cache hit rate: 0.10998439937597504
Row cache capacity: 1000
Row cache size: 1000
Row cache hit rate: 0.0
Compacted row minimum size: 373
Compacted row maximum size: 1331
Compacted row mean size: 574
It is strange but read latency in cfstats is NaN ms
When i calling htop on debian i see that the most load causes phpcassa
I has only one node and use consistency level ONE.
What can cause so slow quering?
I'm guessing you don't have the C extension installed. Without it, a similar query takes 1-2 seconds for me. With it installed, the same query takes about 0.2 seconds.
Regarding the NaN read latency, latencies aren't captured for get_range_slices (get_range in phpcassa).