System information¶
CrateDB provides the sys
schema which contains virtual tables. These tables
are read-only and can be queried to get statistical real-time information about
the cluster, its nodes and their shards:
Table of contents
Cluster¶
Basic information about the CrateDB cluster can be retrieved from the
sys.cluster
table:
Name |
Description |
Return Type |
---|---|---|
|
A unique ID generated by the system. |
|
|
The current CrateDB license information. Always NULL. This exists for backward compatibility |
|
|
The cluster name. |
|
|
Node ID of the node which currently operates as master |
|
|
The cluster settings. |
|
The result has at most 1 row:
cr> select name from sys.cluster;
+-----------------+
| name |
+-----------------+
| Testing-CrateDB |
+-----------------+
SELECT 1 row in set (... sec)
Cluster license¶
The sys.cluster.license
expression returns
information about the currently registered license.
Note
Licenses were removed in CrateDB 4.5. Accordingly, these values are deprecated and return NULL in CrateDB 4.5 and higher.
license
¶
Column Name |
Description |
Return Type |
---|---|---|
|
|
|
|
The Dates and times on which the license expires. |
|
|
The organisation for which the license is issued. |
|
|
The maximum number of nodes the license is valid for. |
|
Cluster settings¶
The sys.cluster.settings
expression returns
information about the currently applied cluster settings.
cr> select settings from sys.cluster;
+-------------------------------------------------------...-+
| settings |
+-------------------------------------------------------...-+
| {"bulk": {...}, "cluster": {...}, "discovery": {...}, ... |
+-------------------------------------------------------...-+
SELECT 1 row in set (... sec)
cr> select column_name, data_type from information_schema.columns
... where column_name like 'settings%'
... and table_name = 'cluster';
+-----------------------------------------------------------------------------------+------------------+
| column_name | data_type |
+-----------------------------------------------------------------------------------+------------------+
| settings | object |
| settings['bulk'] | object |
| settings['bulk']['request_timeout'] | text |
| settings['cluster'] | object |
| settings['cluster']['graceful_stop'] | object |
| settings['cluster']['graceful_stop']['force'] | boolean |
| settings['cluster']['graceful_stop']['min_availability'] | text |
| settings['cluster']['graceful_stop']['timeout'] | text |
| settings['cluster']['info'] | object |
| settings['cluster']['info']['update'] | object |
| settings['cluster']['info']['update']['interval'] | text |
| settings['cluster']['max_shards_per_node'] | integer |
| settings['cluster']['routing'] | object |
| settings['cluster']['routing']['allocation'] | object |
| settings['cluster']['routing']['allocation']['allow_rebalance'] | text |
| settings['cluster']['routing']['allocation']['balance'] | object |
| settings['cluster']['routing']['allocation']['balance']['index'] | real |
| settings['cluster']['routing']['allocation']['balance']['shard'] | real |
| settings['cluster']['routing']['allocation']['balance']['threshold'] | real |
| settings['cluster']['routing']['allocation']['cluster_concurrent_rebalance'] | integer |
| settings['cluster']['routing']['allocation']['disk'] | object |
| settings['cluster']['routing']['allocation']['disk']['threshold_enabled'] | boolean |
| settings['cluster']['routing']['allocation']['disk']['watermark'] | object |
| settings['cluster']['routing']['allocation']['disk']['watermark']['flood_stage'] | text |
| settings['cluster']['routing']['allocation']['disk']['watermark']['high'] | text |
| settings['cluster']['routing']['allocation']['disk']['watermark']['low'] | text |
| settings['cluster']['routing']['allocation']['enable'] | text |
| settings['cluster']['routing']['allocation']['exclude'] | object |
| settings['cluster']['routing']['allocation']['exclude']['_host'] | text |
| settings['cluster']['routing']['allocation']['exclude']['_id'] | text |
| settings['cluster']['routing']['allocation']['exclude']['_ip'] | text |
| settings['cluster']['routing']['allocation']['exclude']['_name'] | text |
| settings['cluster']['routing']['allocation']['include'] | object |
| settings['cluster']['routing']['allocation']['include']['_host'] | text |
| settings['cluster']['routing']['allocation']['include']['_id'] | text |
| settings['cluster']['routing']['allocation']['include']['_ip'] | text |
| settings['cluster']['routing']['allocation']['include']['_name'] | text |
| settings['cluster']['routing']['allocation']['node_concurrent_recoveries'] | integer |
| settings['cluster']['routing']['allocation']['node_initial_primaries_recoveries'] | integer |
| settings['cluster']['routing']['allocation']['require'] | object |
| settings['cluster']['routing']['allocation']['require']['_host'] | text |
| settings['cluster']['routing']['allocation']['require']['_id'] | text |
| settings['cluster']['routing']['allocation']['require']['_ip'] | text |
| settings['cluster']['routing']['allocation']['require']['_name'] | text |
| settings['cluster']['routing']['allocation']['total_shards_per_node'] | integer |
| settings['cluster']['routing']['rebalance'] | object |
| settings['cluster']['routing']['rebalance']['enable'] | text |
| settings['discovery'] | object |
| settings['discovery']['zen'] | object |
| settings['discovery']['zen']['publish_timeout'] | text |
| settings['gateway'] | object |
| settings['gateway']['expected_data_nodes'] | integer |
| settings['gateway']['expected_nodes'] | integer |
| settings['gateway']['recover_after_data_nodes'] | integer |
| settings['gateway']['recover_after_nodes'] | integer |
| settings['gateway']['recover_after_time'] | text |
| settings['indices'] | object |
| settings['indices']['breaker'] | object |
| settings['indices']['breaker']['fielddata'] | object |
| settings['indices']['breaker']['fielddata']['limit'] | text |
| settings['indices']['breaker']['fielddata']['overhead'] | double precision |
| settings['indices']['breaker']['query'] | object |
| settings['indices']['breaker']['query']['limit'] | text |
| settings['indices']['breaker']['query']['overhead'] | double precision |
| settings['indices']['breaker']['request'] | object |
| settings['indices']['breaker']['request']['limit'] | text |
| settings['indices']['breaker']['request']['overhead'] | double precision |
| settings['indices']['breaker']['total'] | object |
| settings['indices']['breaker']['total']['limit'] | text |
| settings['indices']['recovery'] | object |
| settings['indices']['recovery']['internal_action_long_timeout'] | text |
| settings['indices']['recovery']['internal_action_timeout'] | text |
| settings['indices']['recovery']['max_bytes_per_sec'] | text |
| settings['indices']['recovery']['recovery_activity_timeout'] | text |
| settings['indices']['recovery']['retry_delay_network'] | text |
| settings['indices']['recovery']['retry_delay_state_sync'] | text |
| settings['indices']['replication'] | object |
| settings['indices']['replication']['retry_timeout'] | text |
| settings['logger'] | object_array |
| settings['logger']['level'] | text_array |
| settings['logger']['name'] | text_array |
| settings['memory'] | object |
| settings['memory']['allocation'] | object |
| settings['memory']['allocation']['type'] | text |
| settings['overload_protection'] | object |
| settings['overload_protection']['dml'] | object |
| settings['overload_protection']['dml']['initial_concurrency'] | integer |
| settings['overload_protection']['dml']['max_concurrency'] | integer |
| settings['overload_protection']['dml']['min_concurrency'] | integer |
| settings['overload_protection']['dml']['queue_size'] | integer |
| settings['replication'] | object |
| settings['replication']['logical'] | object |
| settings['replication']['logical']['ops_batch_size'] | integer |
| settings['replication']['logical']['reads_poll_duration'] | text |
| settings['replication']['logical']['recovery'] | object |
| settings['replication']['logical']['recovery']['chunk_size'] | text |
| settings['replication']['logical']['recovery']['max_concurrent_file_chunks'] | integer |
| settings['stats'] | object |
| settings['stats']['breaker'] | object |
| settings['stats']['breaker']['log'] | object |
| settings['stats']['breaker']['log']['jobs'] | object |
| settings['stats']['breaker']['log']['jobs']['limit'] | text |
| settings['stats']['breaker']['log']['jobs']['overhead'] | double precision |
| settings['stats']['breaker']['log']['operations'] | object |
| settings['stats']['breaker']['log']['operations']['limit'] | text |
| settings['stats']['breaker']['log']['operations']['overhead'] | double precision |
| settings['stats']['enabled'] | boolean |
| settings['stats']['jobs_log_expiration'] | text |
| settings['stats']['jobs_log_filter'] | text |
| settings['stats']['jobs_log_persistent_filter'] | text |
| settings['stats']['jobs_log_size'] | integer |
| settings['stats']['operations_log_expiration'] | text |
| settings['stats']['operations_log_size'] | integer |
| settings['stats']['service'] | object |
| settings['stats']['service']['interval'] | text |
| settings['udc'] | object |
| settings['udc']['enabled'] | boolean |
| settings['udc']['initial_delay'] | text |
| settings['udc']['interval'] | text |
| settings['udc']['url'] | text |
+-----------------------------------------------------------------------------------+------------------+
SELECT ... rows in set (... sec)
For further details, see the Cluster Settings configuration section.
Nodes¶
To get information about the nodes query for sys.nodes
.
This table can be queried for one, multiple or all nodes within a cluster.
The table schema is as follows:
id
¶
Column Name |
Description |
Return Type |
---|---|---|
|
A unique ID within the cluster generated by the system. |
|
name
¶
Column Name |
Description |
Return Type |
---|---|---|
|
The node name within a cluster. The system will choose a random name. You can also customize the node name, see Node-specific settings. |
|
hostname
¶
Column Name |
Description |
Return Type |
---|---|---|
|
The specified host name of the machine the node is running on. |
|
rest_url
¶
Column Name |
Description |
Return Type |
---|---|---|
|
Full HTTP(s) address where the REST API of the node is exposed, including schema, hostname (or IP) and port. |
|
port
¶
Column Name |
Description |
Return Type |
---|---|---|
|
The specified ports for both HTTP and binary transport interfaces. You can also customize the ports setting, see Ports. |
|
|
CrateDB’s HTTP port. |
|
|
CrateDB’s binary transport port. |
|
|
The PostgreSQL wire protocol port. |
|
load
¶
Column Name |
Description |
Return Type |
---|---|---|
|
System load statistics |
|
|
Average load over the last 1 minute. |
|
|
Average load over the last 5 minutes. |
|
|
Average load over the last 15 minutes. |
|
|
Unix timestamp at the time of collection of the load probe. |
|
mem
¶
Column Name |
Description |
Return Type |
---|---|---|
|
Memory utilization statistics of the host. |
|
|
Currently used memory in bytes. |
|
|
Currently used memory in percent of total. |
|
|
Currently available memory in bytes. |
|
|
Currently available memory in percent of total. |
|
|
Unix timestamp at the time of collection of the memory probe. |
|
heap
¶
Column Name |
Description |
Return Type |
---|---|---|
|
Heap memory utilization statistics. |
|
|
Currently used heap memory in bytes. |
|
|
Maximum available heap memory. You can specify the max heap memory CrateDB should use in the Configuration. |
|
|
Currently available heap memory in bytes. |
|
|
Unix timestamp at the time of collection of the heap probe. |
|
version
¶
Column Name |
Description |
Return Type |
---|---|---|
|
CrateDB version information. |
|
|
Version string in format |
|
|
SHA hash of the GitHub commit which this build was built from. |
|
|
Indicates whether this build is a snapshot build. |
|
|
Indicates the minimum compatible index version which is supported. |
|
|
Indicates the minimum compatible wire protocol version which is supported. |
|
cluster_state_version
¶
Column Name |
Description |
Return Type |
---|---|---|
|
The current version of the cluster state. The cluster state is an immutable structure and that is recreated when a change is published. |
|
fs
¶
Column Name |
Description |
Return Type |
---|---|---|
|
Utilization statistics about the file system. |
|
|
Aggregated usage statistic of all disks on the host. |
|
|
Total size of all disks in bytes. |
|
|
Total used space of all disks in bytes. |
|
|
Total available space of all disks in bytes. |
|
|
Total number of reads on all disks. |
|
|
Total size of reads on all disks in bytes. |
|
|
Total number of writes on all disks. |
|
|
Total size of writes on all disks in bytes. |
|
|
Usage statistics of individual disks on the host. |
|
|
Device name |
|
|
Total size of the disk in bytes. |
|
|
Used space of the disk in bytes. |
|
|
Available space of the disk in bytes. |
|
|
Information about data paths used by the node. |
|
|
Device name |
|
|
File path where the data of the node resides. |
|
thread_pools
¶
Column Name |
Description |
Return Type |
---|---|---|
|
Usage statistics of Java thread pools. |
|
|
Name of the pool. |
|
|
Number of currently running thread in the thread pool. |
|
|
Total number of rejected threads in the thread pool. |
|
|
Largest number of threads that have ever simultaneously been in the pool. |
|
|
Total number of completed thread in the thread pool. |
|
|
Size of the thread pool. |
|
|
Number of thread currently in the queue. |
|
os
¶
Column Name |
Description |
Return Type |
---|---|---|
|
Operating system stats |
|
|
System uptime in milliseconds Requires allowing system calls on Windows and macOS. See notes in Uptime limitations. |
|
|
UNIX timestamp in millisecond resolution |
|
|
Information about CPU utilization |
|
|
System CPU usage as percentage |
|
|
Unix timestamp at the time of collection of the OS probe. |
|
|
Information about cgroups (Linux only) |
|
|
Information about CPU accounting |
|
|
The path to the CPU accounting cgroup |
|
|
The total CPU time (in nanoseconds) consumed by all tasks in this cgroup. |
|
|
Information about the CPU subsystem |
|
|
The path to the CPU cgroup |
|
|
The period of time (in microseconds) the cgroup access to the CPU gets reallocated. |
|
|
The total amount of time (in microseconds) for which all tasks in the cgroup can run during one period (cfs_period_micros). |
|
|
The nr. of period intervals (cfs_period_micros) that have elapsed. |
|
|
The nr. of times tasks in the cgroup have been throttled. |
|
|
The total time (in nanoseconds) for which tasks in the cgroup have been throttled. |
|
|
Information about memory resources used by tasks in a cgroup. |
|
|
The path to the memory cgroup |
|
|
The total current memory usage by processes in the cgroup. |
|
|
The max. amount of user memory in the cgroup. |
|
The CPU information values are cached for 1s. They might differ from the actual
values at query time. Use the probe timestamp to get the time of collection.
When analyzing the CPU usage over time, always use os['probe_timestamp']
to
calculate the time difference between 2 probes.
cgroup limitations¶
Note
cgroup metrics only work if the stats are available from
/sys/fs/cgroup/cpu
and /sys/fs/cgroup/cpuacct
.
Uptime limitations¶
Note
os[‘uptime’] required a system call when running CrateDB on Windows or
macOS, however, system calls are not permitted by default. If you require
this metric you need to allow system calls by setting bootstrap.seccomp
to false
. This setting must be set in the crate.yml or via command line
argument and cannot be changed at runtime.
os_info
¶
Column Name |
Description |
Return Type |
---|---|---|
|
Operating system information |
|
|
Number of processors that are available in the JVM. This is usually equal to the number of cores of the CPU. |
|
|
Name of the operating system (ex: Linux, Windows, macOS) |
|
|
Name of the JVM architecture (ex: amd64, x86) |
|
|
Version of the operating system |
|
|
Information about the JVM (Java Virtual Machine) |
|
|
The JVM version |
|
|
The name of the JVM (e.g. OpenJDK, Java HotSpot(TM) ) |
|
|
The vendor name of the JVM |
|
|
The version of the JVM |
|
network
¶
Network statistics are deprecated in CrateDB 2.3 and may completely be removed
in subsequent versions. All BIGINT
columns always return 0
.
Column Name |
Description |
Return Type |
---|---|---|
|
Statistics about network activity on the host. |
|
|
Unix timestamp at the time of collection of the network probe. |
|
|
TCP network activity on the host. |
|
|
Information about TCP network connections. |
|
|
Total number of initiated TCP connections. |
|
|
Total number of accepted TCP connections. |
|
|
Total number of currently established TCP connections. |
|
|
Total number of dropped TCP connections. |
|
|
Total number of TCP connections that have been dropped before they were accepted. |
|
|
Information about TCP packets. |
|
|
Total number of TCP packets sent. |
|
|
Total number of TCP packets received. |
|
|
Total number of TCP packets retransmitted due to an error. |
|
|
Total number of TCP packets that contained checksum errors, had a bad offset, were dropped because of a lack of memory or were too short. |
|
|
Total number of RST packets sent due to left unread data in queue when socket is closed. See tools.ietf.org. |
|
connections
¶
Column Name |
Description |
Return Type |
---|---|---|
|
Number of connections established via HTTP |
|
|
The currently open connections established via HTTP |
|
|
The total number of connections that have been established via HTTP over the life time of a CrateDB node |
|
|
Number of connections established via PostgreSQL protocol |
|
|
The currently open connections established via PostgreSQL protocol |
|
|
The total number of connections that have been established via PostgreSQL protocol over the life time of a CrateDB node |
|
|
Number of connections established via Transport protocol |
|
|
The currently open connections established via Transport protocol |
|
process
¶
Column Name |
Description |
Return Type |
---|---|---|
|
Statistics about the CrateDB process. |
|
|
Number of currently open file descriptors used by the CrateDB process. |
|
|
The maximum number of open file descriptors CrateDB can use. |
|
|
The system UNIX timestamp at the moment of the probe collection. |
|
|
Information about the CPU usage of the CrateDB process. |
|
|
The CPU usage of the CrateDB JVM process given in percent. |
|
The CPU information values are cached for 1s. They might differ from the actual
values at query time. Use the probe timestamp to get the time of the collect.
When analyzing the CPU usage over time, always use
process['probe_timestamp']
to calculate the time difference between 2
probes.
Note
If one of the queried nodes is not responding within three seconds it
returns null
every column except id
and name
. This behaviour
could be used to detect hanging nodes.
Node checks¶
The table sys.node_checks
exposes a list of internal node checks and
results of their validation.
The table schema is the following:
Column Name |
Description |
Return Type |
---|---|---|
|
The unique check ID. |
|
|
The unique node ID. |
|
|
The level of severity. The higher the value of the field the higher severity. |
|
|
The description message for the setting check. |
|
|
The flag determines whether the check for the setting has passed. |
|
|
The flag determines whether the
check for this setting has been
acknowledged by the user in
order to ignored the value of
|
|
Example query:
cr> select id, node_id, description from sys.node_checks order by id, node_id;
+----+---------...-+--------------------------------------------------------------...-+
| id | node_id | description |
+----+---------...-+--------------------------------------------------------------...-+
| 1 | ... | The value of the cluster setting 'gateway.expected_data_nodes... |
| 2 | ... | The value of the cluster setting 'gateway.recover_after_data_... |
| 3 | ... | If any of the "expected data nodes" recovery settings are set... |
| 5 | ... | The high disk watermark is exceeded on the node. The cluster ... |
| 6 | ... | The low disk watermark is exceeded on the node. The cluster w... |
| 7 | ... | The flood stage disk watermark is exceeded on the node. Table... |
| 8 | ... | The amount of shards on the node reached 90 % of the limit of... |
+----+---------...-+--------------------------------------------------------------...-+
SELECT 7 rows in set (... sec)
Acknowledge failed checks¶
It is possible to acknowledge every check by updating the acknowledged
column. By doing this, specially CrateDB’s built-in Admin UI won’t complain
anymore about failing checks.
Imagine we’ve added a new node to our cluster, but as the gateway.expected_data_nodes column can only be set via config-file or command-line argument, the check for this setting will not pass on the already running nodes until the config-file or command-line argument on these nodes is updated and the nodes are restarted (which is not what we want on a healthy well running cluster).
In order to make the Admin UI accept a failing check (so the checks label goes
green again), we must acknowledge this check by updating it’s acknowledged
flag:
cr> update sys.node_checks set acknowledged = true where id = 1;
UPDATE OK, 1 row affected (... sec)
Caution
Updates on this column are transient, so changed values are lost after the affected node is restarted.
Description of checked node settings¶
Recovery expected data nodes¶
The check for the gateway.expected_data_nodes setting checks that the number of data nodes that should be waited for the immediate cluster state recovery. This value must be equal to the maximum number of data nodes in the cluster.
Note
For backward compatibility, setting the deprecated gateway.expected_nodes instead is still supported. It must then be equal to the maximum of data and master nodes.
Recovery after data nodes¶
The check for the gateway.recover_after_data_nodes verifies that the number of started nodes before the cluster starts must be greater than the half of the expected number of data nodes and equal to or less than number of data nodes in the cluster.
Note
For backward compatibility, setting the deprecated gateway.recover_after_nodes instead is still supported. It must then be equal to less than the number data and master nodes.
(E / 2) < R <= E
Here, R
is the number of recovery nodes and
E
is the number of expected nodes.
Recovery after time¶
If gateway.recover_after_data_nodes
is set, then gateway.recover_after_time
must not be set to 0s
, otherwise the gateway.recover_after_data_nodes
setting wouldn’t have any effect.
Note
For backward compatibility, setting the deprecated gateway.recover_after_nodes instead is still supported.
Routing allocation disk watermark high¶
The check for the cluster.routing.allocation.disk.watermark.high setting verifies that the high watermark is not exceeded on the current node. The usage of each disk for configured CrateDB data paths is verified against the threshold setting. If one or more verification fails the check is marked as not passed.
Routing allocation disk watermark low¶
The check for the cluster.routing.allocation.disk.watermark.low which controls the low watermark for the node disk usage. The check verifies that the low watermark is not exceeded on the current node. The verification is done against each disk for configured CrateDB data paths. The check is not passed if the verification for one or more disk fails.
Maximum shards per node¶
The check verifies that the amount of shards on the current node is less than 90 percent of cluster.max_shards_per_node. Creating new tables or partitions which would push the number of shards beyond 100 % of the limit will be rejected.
Segments¶
The sys.segments
table contains information about the Lucene segments
of the shards.
The segment information is useful to understand the behaviour of the underlying Lucene file structures for troubleshooting and performance optimization of shards.
Column Name |
Description |
Return Type |
---|---|---|
|
Name of the segment, derived from the segment generation and used internally to create file names in the directory of the shard. |
|
|
ID of the effected shard. |
|
|
Schema name of the table of the shard. |
|
|
Table name of the shard. |
|
|
The partition ident of a partitioned table. Empty for non-partitioned tables. |
|
|
Information about the node the shard is located at. |
|
|
The name of the node the shard is located at. |
|
|
The id of the node the shard is located at. |
|
|
Generation number of the segment, increments for each segment written. |
|
|
Number of non-deleted Lucene documents in this segment. |
|
|
Number of deleted Lucene documents in this segment. |
|
|
Disk space used by the segment in bytes. |
|
|
Segment data stored in memory for efficient search, -1 if it is unavailable. |
|
|
Indicates if the segments are synced to disk. Segments that are synced can survive a hard reboot. |
|
|
Describes if this segment is part of a primary shard. |
|
|
Indicates if the segment is searchable. If |
|
|
Version of Lucene used to write the segment. |
|
|
If |
|
|
Contains information about whether high compression was enabled. |
|
Note
The information in the sys.segments
table is expensive to calculate and
therefore this information should be retrieved with awareness that it can
have performance implications on the cluster.
Note
The sys.shards
table is subject to Shard table permissions.
Jobs, operations, and logs¶
To let you inspect the activities currently taking place in a cluster, CrateDB provides system tables that let you track current cluster jobs and operations. See Jobs Table and Operations Table.
Jobs and operations that finished executing are additionally recorded in memory. There are two retention policies available to control how many records should be kept.
One option is to configure the maximum number of records which should be kept. Once the configured table size is reached, the older log records are deleted as newer records are added. This is configurable using stats.jobs_log_size and stats.operations_log_size.
Another option is to configure an expiration time for the records. In this case, the records in the logs tables are periodically cleared if they are older than the expiry time. This behaviour is configurable using stats.jobs_log_expiration and stats.operations_log_expiration.
In addition to these retention policies, there is a memory limit in place preventing these tables from taking up too much memory. The amount of memory that can be used to store the jobs can be configured using stats.breaker.log.jobs.limit and stats.breaker.log.operations.limit. If the memory limit is reached, an error message will be logged and the log table will be cleared completely.
It is also possible to define a filter which must match for jobs to be recorded after they finished executing. This can be useful to only record slow queries or queries that failed due to an error. This filter can be configured using the stats.jobs_log_filer setting.
Furthermore, there is a second filter setting which also results in a log entry in the regular CrateDB log file for all finished jobs that match this filter. This can be configured using stats.jobs_log_persistent_filter. This could be used to create a persistent slow query log.
Jobs¶
The sys.jobs
table is a constantly updated view of all jobs that are
currently being executed in the cluster.
Table schema¶
Column Name |
Description |
Return Type |
---|---|---|
|
The job UUID. This job ID is generated by the system. |
|
|
Information about the node that created the job. |
|
|
The id of the node. |
|
|
The name of the node. |
|
|
The point in time when the job started. |
|
|
Shows the data query or manipulation statement represented by this job. |
|
|
The user who is executing the statement. |
|
The field username
corresponds to the SESSION_USER
that is performing the query:
cr> select stmt, username, started from sys.jobs where stmt like 'sel% from %jobs%';
+---------------------------------------------------------------------------------+----------+-...-----+
| stmt | username | started |
+---------------------------------------------------------------------------------+----------+-...-----+
| select stmt, username, started from sys.jobs where stmt like 'sel% from %jobs%' | crate | ... |
+---------------------------------------------------------------------------------+----------+-...-----+
SELECT 1 row in set (... sec)
Note
If the user management module is not available, the username
is
given as crate
.
Every request that queries data or manipulates data is considered a “job” if it is a valid query. Requests that are not valid queries (for example, a request that tries to query a non-existent table) will not show up as jobs.
Note
The sys.jobs
table is subject to sys jobs tables permissions.
Jobs metrics¶
The sys.jobs_metrics
table provides an overview of the query latency in the
cluster. Jobs metrics are not persisted across node restarts.
The metrics are aggregated for each node and each unique classification of the statements.
Note
In order to reduce the memory requirements for these metrics, the times are statistically sampled and therefore may have slight inaccuracies. In addition, durations are only tracked up to 10 minutes. Statements taking longer than that are capped to 10 minutes.
sys.jobs_metrics
Table schema¶
Column Name |
Description |
Return Type |
---|---|---|
|
An object containing the id and name of the node on which the metrics have been sampled. |
|
|
An object containing the statement classification. |
|
|
The general type of the statement. Types are:
|
|
|
Labels are only available for certain statement types that can be classified more accurately than just by their type. |
|
|
Total number of queries executed |
|
|
Total number of queries that failed to complete successfully. |
|
|
Sum of durations in ms of all executed queries per statement type. |
|
|
The standard deviation of the query latencies |
|
|
The mean query latency in ms |
|
|
The maximum query latency in ms |
|
|
The minimum query latency in ms |
|
|
An object containing different percentiles |
|
Classification¶
Certain statement types (such as SELECT
statements) have additional labels
in their classification. These labels are the names of the logical plan
operators that are involved in the query.
For example, the following UNION
statement:
SELECT name FROM t1 where id = 1
UNION ALL
SELECT name FROM t2 where id < 2
would result in the following labels:
Union`
for the UNION ALLGet
for the left SELECTCollect
for the right SELECT
Note
Labels may be subject to change as they only represent internal properties of the statement!
Operations¶
The sys.operations
table is a constantly updated view of all operations
that are currently being executed in the cluster:
cr> select node['name'], job_id, name, used_bytes from sys.operations
... order by name limit 1;
+--------------+--------...-+-----...-+------------+
| node['name'] | job_id | name | used_bytes |
+--------------+--------...-+-----...-+------------+
| crate | ... | ... | ... |
+--------------+--------...-+-----...-+------------+
SELECT 1 row in set (... sec)
An operation is a node-specific sub-component of a job (for when a job involves multi-node processing). Jobs that do not require multi-node processing will not produce any operations.
Table schema¶
Column Name |
Description |
Return Type |
---|---|---|
|
The operation UUID. This operation ID is generated by the system. |
|
|
The job id this operation belongs to. |
|
|
The name of the operation. |
|
|
Information about the node that created the operation. |
|
|
The id of the node. |
|
|
The name of the node. |
|
|
The point in time when the operation started. |
|
|
Currently loaded amount of data by the operation. |
|
Note
In some cases, operations are generated for internal CrateDB work that does
not directly correspond to a user request. These entries do not have
corresponding entries in sys.jobs
.
Logs¶
The sys.jobs and sys.operations tables
have corresponding log tables: sys.jobs_log
and sys.operations_log
.
sys.jobs_log
Table schema¶
Column Name |
Description |
Return Type |
---|---|---|
|
The job ID. |
|
|
The point in time when the job finished. |
|
|
If the job encountered an error, this will hold the error message. |
|
|
The point in time when the job started. |
|
|
Shows the data query or manipulation statement executed by the job. |
|
|
The user who executed the statement. |
|
|
An object containing the statement classification. |
|
|
The general type of the statement.
Types are: |
|
|
Labels are only available for certain statement types that can be classified more accurately than just by their type. |
|
|
Information about the node that created the job. |
|
|
The id of the node. |
|
|
The name of the node. |
|
Note
You can control which jobs are recorded using the stats.jobs_log_filter
Note
The sys.jobs_log
table is subject to sys jobs tables permissions.
sys.operations_log
Table schema¶
Column Name |
Description |
Return Type |
---|---|---|
|
The operation ID. |
|
|
The job id. |
|
|
The point in time when the operation finished. |
|
|
If the operation encountered an error, this will hold the error message. |
|
|
The name of the operation. |
|
|
The point in time when the operation started. |
|
|
The amount of data loaded by the operation. |
|
After a job or operation finishes, the corresponding entry will be moved into the corresponding log table:
cr> select id, stmt, username, started, ended, error
... from sys.jobs_log order by ended desc limit 2;
+-...+----------------------------------------------...-+----------+-...-----+-...---+-------+
| id | stmt | username | started | ended | error |
+-...+----------------------------------------------...-+----------+-...-----+-...---+-------+
| ...| select node['name'], ... | crate | ... | ... | NULL |
| ...| select stmt, username, started from sys.jobs ... | crate | ... | ... | NULL |
+-...+----------------------------------------------...-+----------+-...-----+-...---+-------+
SELECT 2 rows in set (... sec)
Invalid queries are also logged in the sys.jobs_log
table, i.e. queries
that never make it to the sys.jobs
table because they could not be
executed.
The log tables are bound by a fixed size (stats.jobs_log_size) or by an expiration time (stats.jobs_log_expiration)
See Collecting stats for information on how to configure logs.
Caution
If you deactivate statistics tracking, the logs tables will be truncated.
Cluster checks¶
The table sys.checks
exposes a list of internal cluster checks and results
of their validation.
The sys.checks
table looks like this:
Column Name |
Description |
Return Type |
---|---|---|
|
The unique check id. |
|
|
The level of severity. The higher the value of the field the higher severity. |
|
|
The description message for the setting check. |
|
|
The flag determines whether the check for the setting has passed. |
|
Here’s an example query:
cr> select id, description from sys.checks order by id;
+----+--------------------------------------------------------------...-+
| id | description |
+----+--------------------------------------------------------------...-+
| 2 | The total number of partitions of one or more partitioned tab... |
| 3 | The following tables need to be recreated for compatibility w... |
+----+--------------------------------------------------------------...-+
SELECT 2 rows in set (... sec)
Cluster checks are also indicated in the CrateDB admin console. When all cluster checks (and all Node checks) pass, the Checks icon will be green. Here’s what it looks like when some checks are failing at the CRITICAL severity level:
Current Checks¶
Number of partitions¶
This check warns if any partitioned table has more than 1000 partitions to detect the usage of a high cardinality field for partitioning.
Tables need to be recreated¶
Warning
Do not attempt to upgrade your cluster to a newer major version if this cluster check is failing. Follow the instructions below to get this cluster check passing.
This check warns you if your cluster contains tables that you need to reindex before you can upgrade to a future major version of CrateDB.
If you try to upgrade to a later major CrateDB version without reindexing the tables, CrateDB will refuse to start.
CrateDB table version compatibility scheme¶
CrateDB maintains backward compatibility for tables created in majorVersion - 1
:
Table Origin |
Current Version |
Current Version |
Current Version |
3.x |
4.x |
5.x |
|
3.x |
✔️ |
✔️ |
❌ |
4.x |
❌ |
✔️ |
✔️ |
5.x |
❌ |
❌ |
✔️ |
Avoiding reindex using partitioned tables¶
Reindexing tables is an expensive operation which can take a long time. If you are storing time series data for a certain retention period and intend to delete old data, it is possible to use the partitioned tables to avoid reindex operations.
You will have to use a partition column that
denotes time. For example, if you have a retention period of nine months, you
could partition a table by a month
column. Then, every month, the system
will create a new partition. This new partition is created using the active
CrateDB version and is compatible with the next major CrateDB version. Now to
achieve your goal of avoiding a reindex, you must manually delete any partition
older than nine months. If you do that, then after nine months you rolled
through all partitions and the remaining nine are compatible with the next
major CrateDB version.
How to reindex¶
Use SHOW CREATE TABLE to get the schema required to create an empty copy of the table to recreate:
cr> SHOW CREATE TABLE rx.metrics; +-----------------------------------------------------+ | SHOW CREATE TABLE rx.metrics | +-----------------------------------------------------+ | CREATE TABLE IF NOT EXISTS "rx"."metrics" ( | | "id" TEXT NOT NULL, | | "temperature" REAL, | | PRIMARY KEY ("id") | | ) | | CLUSTERED BY ("id") INTO 4 SHARDS | | WITH ( | | "allocation.max_retries" = 5, | | "blocks.metadata" = false, | | "blocks.read" = false, | | "blocks.read_only" = false, | | "blocks.read_only_allow_delete" = false, | | "blocks.write" = false, | | codec = 'default', | | column_policy = 'strict', | | "mapping.total_fields.limit" = 1000, | | max_ngram_diff = 1, | | max_shingle_diff = 3, | | number_of_replicas = '0-1', | | "routing.allocation.enable" = 'all', | | "routing.allocation.total_shards_per_node" = -1, | | "store.type" = 'fs', | | "translog.durability" = 'REQUEST', | | "translog.flush_threshold_size" = 536870912, | | "translog.sync_interval" = 5000, | | "unassigned.node_left.delayed_timeout" = 60000, | | "write.wait_for_active_shards" = '1' | | ) | +-----------------------------------------------------+ SHOW 1 row in set (... sec)
Create a new temporary table, using the schema returned from SHOW CREATE TABLE:
cr> CREATE TABLE rx.tmp_metrics (id TEXT PRIMARY KEY, temperature REAL); CREATE OK, 1 row affected (... sec)
Copy the data:
cr> INSERT INTO rx.tmp_metrics (id, temperature) (SELECT id, temperature FROM rx.metrics); INSERT OK, 2 rows affected (... sec)
Swap the tables:
cr> ALTER CLUSTER SWAP TABLE rx.tmp_metrics TO rx.metrics; ALTER OK, 1 row affected (... sec)
Confirm the new
your_table
contains all data and has the new version:cr> SELECT count(*) FROM rx.metrics; +----------+ | count(*) | +----------+ | 2 | +----------+ SELECT 1 row in set (... sec) cr> SELECT version['created'] FROM information_schema.tables ... WHERE table_schema = 'rx' AND table_name = 'metrics'; +--------------------+ | version['created'] | +--------------------+ | 4.8.5 | +--------------------+ SELECT 1 row in set (... sec)
Drop the old table, as it is now obsolete:
cr> DROP TABLE rx.tmp_metrics; DROP OK, 1 row affected (... sec)
After you reindexed all tables, this cluster check will pass.
Note
Snapshots of your tables created prior to them being upgraded will not work with future versions of CrateDB. For this reason, you should create a new snapshot for each of your tables. (See Snapshots.)
License check¶
Note
This check was removed in version 4.5 because CrateDB no longer requires an enterprise license, see also Farewell to the CrateDB Enterprise License.
This check warns you when your license is close to expiration, is already
expired, or if the cluster contains more nodes than allowed by your license. It
will yield a MEDIUM
alert when your license is valid for less than 15 days
and a HIGH
alert when your license is valid for less than a day.
All other cases, like already expired or max-nodes-violation, it will
result in a HIGH
alert. We recommend that you request a new license when
this check triggers, in order to avoid the situation where operations are
rejected due to an invalid license.
Health¶
The sys.health
table lists the health of each table and table
partition. The health is computed by checking the states of the shard of each
table/partition.
Column Name |
Description |
Return Type |
---|---|---|
|
The table name. |
|
|
The schema of the table. |
|
|
The ident of the partition. NULL for non-partitioned tables. |
|
|
The health label. Can be RED, YELLOW or GREEN. |
|
|
The health as a |
|
|
The number of not assigned or started shards. |
|
|
The number of shards which are not fully replicated. |
|
Both missing_shards
and underreplicated_shards
might return -1
if
the cluster is in an unhealthy state that prevents the exact number from being
calculated. This could be the case when the cluster can’t elect a master,
because there are not enough eligible nodes available.
cr> select * from sys.health order by severity desc, table_name;
+--------+----------------+-----------------+----------+------------+--------------+------------------------+
| health | missing_shards | partition_ident | severity | table_name | table_schema | underreplicated_shards |
+--------+----------------+-----------------+----------+------------+--------------+------------------------+
| GREEN | 0 | NULL | 1 | locations | doc | 0 |
| GREEN | 0 | NULL | 1 | quotes | doc | 0 |
+--------+----------------+-----------------+----------+------------+--------------+------------------------+
SELECT 2 rows in set (... sec)
The health with the highest severity will always define the health of the query scope.
Example of getting a cluster health (health of all tables):
cr> select health from sys.health order by severity desc limit 1;
+--------+
| health |
+--------+
| GREEN |
+--------+
SELECT 1 row in set (... sec)
Health definition¶
Health |
Description |
---|---|
|
At least one primary shard is missing (primary shard not started or unassigned). |
|
At least one shard is underreplicated (replica shard not started or unassigned). |
|
All primary and replica shards have been started. |
Note
The sys.health
table is subject to Shard table permissions as it
will expose a summary of table shard states.
Repositories¶
The table sys.repositories
lists all configured repositories that can be
used to create, manage and restore snapshots (see Snapshots).
Column Name |
Description |
Return Type |
---|---|---|
|
The repository name |
|
|
The type of the repository determining how and where the repository stores its snapshots. |
|
|
The configuration settings the repository has been created with. The specific settings depend on the repository type, see CREATE REPOSITORY. |
|
cr> SELECT name, type, settings FROM sys.repositories
... ORDER BY name;
+---------+------+---------------------------------------------------...--+
| name | type | settings |
+---------+------+---------------------------------------------------...--+
| my_repo | fs | {"compress": "true", "location": "repo_location", ...} |
+---------+------+---------------------------------------------------...--+
SELECT 1 row in set (... sec)
Note
Sensitive user account information will be masked and thus not visible to the user.
Snapshots¶
The table sys.snapshots
lists all existing snapshots in all configured
repositories (see Snapshots).
Column Name |
Description |
Return Type |
---|---|---|
|
The name of the snapshot |
|
|
The name of the repository that contains this snapshot. |
|
|
Contains the names of all tables and partitions that are contained in this snapshot how they are represented as ES index names. |
|
|
Contains the fully qualified names of all tables within the snapshot. |
|
|
Contains the table schema, table name and partition values of partitioned tables within the snapshot. |
|
|
The point in time when the creation of the snapshot started. Changes made after that are not stored in this snapshot. |
|
|
The point in time when the snapshot creation finished. |
|
|
The current state of the
snapshot. One of:
|
|
|
An internal version this snapshot was created with. |
|
|
A list of failures that occurred while taking the snapshot. If taking the snapshot was successful this is empty. |
|
Snapshot/Restore operates on a per-shard basis. Hence, the state
column
indicates whether all (SUCCESS
), some (PARTIAL
), or no
shards(FAILED
) have been backed up. PARTIAL
snapshots are the result of
some primaries becoming unavailable while taking the snapshot when there are no
replicas at hand (cluster state is RED). If there are replicas of the (now
unavailable) primaries (cluster state is YELLOW) the snapshot succeeds and
all shards are included (state SUCCESS
). Building on a PARTIAL
snapshot
will include all primaries again.
Warning
In case of a PARTIAL
state another snapshot should be created in order
to guarantee a full backup! Only SUCCESS
includes all shards.
The concrete_indices
column contains the names of all Elasticsearch indices
that were stored in the snapshot. A normal CrateDB table maps to one
Elasticsearch index, a partitioned table maps to one Elasticsearch index per
partition. The mapping follows the following pattern:
CrateDB table / partition name |
|
---|---|
|
|
|
|
|
|
|
|
cr> SELECT "repository", name, state, concrete_indices
... FROM sys.snapshots order by "repository", name;
+------------+-------------+---------+-----------------...-+
| repository | name | state | concrete_indices |
+------------+-------------+---------+-----------------...-+
| my_repo | my_snapshot | SUCCESS | [...] |
+------------+-------------+---------+-----------------...-+
SELECT 1 row in set (... sec)
Snapshot Restore¶
The sys.snapshot_restore
table contains information about the current
state of snapshot restore operations.
Name |
Description |
Type |
---|---|---|
|
The |
|
|
The name of the repository that contains the snapshot. |
|
|
The name of the snapshot. |
|
|
The current state of the snapshot restore operations. Possible states
are: |
|
|
The schema name of the table of the shard. |
|
|
The table name of the shard. |
|
|
The identifier of the partition of the shard. |
|
|
The ID of the shard. |
|
|
The restore state of the shard. Possible states are: |
|
To get more information about the restoring snapshots and shards one can join
the sys.snapshot_restore
with sys.shards
or sys.snapshots
table.
Summits¶
The sys.summits
table contains the information about the mountains in the
Alps higher than 2000m. The mountain names from the table are also used to
generate random nodes names.
Users¶
The sys.users
table contains all existing database users in the cluster.
Column Name |
Description |
Return Type |
---|---|---|
|
The name of the database user. |
|
|
Flag to indicate whether the user is a superuser. |
|
Allocations¶
The sys.allocations
table contains information about shards and their
allocation state. The table contains:
shards that are unassigned and why they are unassigned
shards that are assigned but cannot be moved or rebalanced and why they remain on their current node
It can help to identify problems if shard allocations behave different than expected, e.g. when a shard stays unassigned or a shard does not move off a node.
Column Name |
Description |
Return Type |
---|---|---|
|
Schema name of the table of the shard. |
|
|
Table name of the shard. |
|
|
Identifier of the partition
of the shard.
|
|
|
ID of the effected shard. |
|
|
ID of the node on which the
shard resides. |
|
|
Whether the shard is a primary shard. |
|
|
Current state of the shard.
Possible states are:
|
|
|
Explanation why the shard cannot be allocated, moved or rebalanced. |
|
|
A list of decisions that describe in detail why the shard in the current state. |
|
|
ID of the node of the decision. |
|
|
Name of the node of the decision. |
|
|
Detailed list of human
readable explanations why the
node decided whether to
allocate or rebalance the
shard. Returns |
|
Note
The sys.allocations
table is subject to Shard table permissions.
sys
jobs tables permissions¶
Accessing sys.jobs and sys.jobs_log tables
is subjected to the same privileges constraints as other tables. To query
them, the current user needs to have the DQL
privilege on that particular
table, either directly or inherited from the SCHEMA
or CLUSTER
.
A user that doesn’t have superuser privileges is allowed to retrieve only their own job logs entries, while a user with superuser privileges has access to all.
pg_stats¶
The pg_stats
table in the pg_catalog
system schema contains statistical
data about the contents of the CrateDB cluster.
Entries are periodically created or updated in the interval configured with the stats.service.interval setting.
Alternatively the statistics can also be updated using the ANALYZE command.
The table contains 1 entry per column for each table in the cluster which has been analyzed.
Name |
Type |
Description |
---|---|---|
schemaname |
text |
Name of the schema containing the table. |
tablename |
text |
Name of the table. |
attname |
text |
Name of the column. |
inherited |
bool |
Always false in CrateDB; For compatibility with PostgreSQL. |
null_frac |
real |
Fraction of column entries that are null. |
avg_width |
integer |
Average size in bytes of column’s entries. |
n_distinct |
real |
An approximation of the number of distinct values in a column. |
most_common_vals |
string[] |
A list of the most common values in the column. null if no values seem. more common than others. |
most_common_freqs |
real[] |
A list of the frequencies of the most common values. The size of the array always matches most_common_vals. If most_common_vals is null this is null as well. |
histogram_bounds |
string[] |
A list of values that divide the column’s values into groups of approximately equal population. The values in most_common_vals, if present, are omitted from this histogram calculation. |
correlation |
real |
Always 0.0. This column exists for PostgreSQL compatibility. |
most_common_elems |
string[] |
Always null. Exists for PostgreSQL compatibility. |
most_common_elem_freqs |
real[] |
Always null. Exists for PostgreSQL compatibility. |
elem_count_histogram |
real[] |
Always null. Exists for PostgreSQL compatibility. |
Note
Not all data types support creating statistics. So some columns may not show up in the table.
pg_publication¶
The pg_publication
table in the pg_catalog
system schema contains all
publications created in the cluster.
Column Name |
Description |
Return Type |
---|---|---|
|
Row identifier. |
|
|
Name of the publication. |
|
|
|
|
|
Whether this publication includes all tables in the cluster, including tables created in the future. |
|
|
Whether |
|
|
Whether |
|
|
Whether |
|
pg_publication_tables¶
The pg_publication_tables
table in the pg_catalog
system schema
contains tables replicated by a publication.
Column Name |
Description |
Return Type |
---|---|---|
|
Name of the publication. |
|
|
Name of the schema containing table. |
|
|
Name of the table. |
|
pg_subscription¶
The pg_subscription
table in the pg_catalog
system schema contains all
subscriptions created in the cluster.
Column Name |
Description |
Return Type |
---|---|---|
|
Row identifier. |
|
|
noop value, always |
|
|
Name of the subscription. |
|
|
|
|
|
Whether the subscription is enabled,
always |
|
|
Noop value, always |
|
|
Noop value, always |
|
|
Connection string to the publishing cluster. |
|
|
Noop value, always |
|
|
Noop value, always |
|
|
Array of subscribed publication names. These publications are defined in the publishing cluster. |
|
pg_subscription_rel¶
The pg_subscription_rel
table in the pg_catalog
system schema
contains the state for each replicated relation in each subscription.
Column Name |
Description |
Return Type |
---|---|---|
|
Reference to subscription. |
|
|
Reference to relation. |
|
|
Replication state of the relation.
State code:
|
|
|
Error message if there was a
replication error for the relation
or |
|
|
Noop value, always |
|