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

id

A unique ID generated by the system.

TEXT

license

The current CrateDB license information. Always NULL. This exists for backward compatibility

OBJECT

name

The cluster name.

TEXT

master_node

Node ID of the node which currently operates as master

TEXT

settings

The cluster settings.

OBJECT

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

license

The current CrateDB license information

or NULL on CrateDB CE.

OBJECT

license['expiry_date']

The Date and time types on which the license expires.

TIMESTAMP WITH TIME ZONE

license['issued_to']

The organisation for which the license is issued.

TEXT

license['max_nodes']

The maximum number of nodes the license is valid for.

INTEGER

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_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['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['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

id

A unique ID within the cluster generated by the system.

TEXT

name

Column Name

Description

Return Type

name

The node name within a cluster. The system will choose a random name. You can also customize the node name, see Node-specific settings.

TEXT

hostname

Column Name

Description

Return Type

hostname

The specified host name of the machine the node is running on.

TEXT

rest_url

Column Name

Description

Return Type

rest_url

Full http(s) address where the REST API of the node is exposed, including schema, hostname (or IP) and port.

TEXT

port

Column Name

Description

Return Type

port

The specified ports for both HTTP and binary transport interfaces. You can also customize the ports setting, see Ports.

OBJECT

port['http']

CrateDB’s HTTP port.

INTEGER

port['transport']

CrateDB’s binary transport port.

INTEGER

port['psql']

The PostgreSQL wire protocol port.

INTEGER

load

Column Name

Description

Return Type

load

System load statistics

OBJECT

load['1']

Average load over the last 1 minute.

DOUBLE PRECISION

load['5']

Average load over the last 5 minutes.

DOUBLE PRECISION

load['15']

Average load over the last 15 minutes.

DOUBLE PRECISION

load['probe_timestamp']

Unix timestamp at the time of collection of the load probe.

BIGINT

mem

Column Name

Description

Return Type

mem

Memory utilization statistics of the host.

OBJECT

mem['used']

Currently used memory in bytes.

BIGINT

mem['used_percent']

Currently used memory in percent of total.

SMALLINT

mem['free']

Currently available memory in bytes.

BIGINT

mem['free_percent']

Currently available memory in percent of total.

SMALLINT

mem['probe_timestamp']

Unix timestamp at the time of collection of the memory probe.

BIGINT

heap

Column Name

Description

Return Type

heap

Heap memory utilization statistics.

OBJECT

heap['used']

Currently used heap memory in bytes.

BIGINT

heap['max']

Maximum available heap memory. You can specify the max heap memory CrateDB should use in the Configuration.

BIGINT

heap['free']

Currently available heap memory in bytes.

BIGINT

heap['probe_timestamp']

Unix timestamp at the time of collection of the heap probe.

BIGINT

version

Column Name

Description

Return Type

version

CrateDB version information.

OBJECT

version['number']

Version string in format "major.minor.hotfix"

TEXT

version['build_hash']

SHA hash of the Github commit which this build was built from.

TEXT

version['build_snapshot']

Indicates whether this build is a snapshot build.

BOOLEAN

version['minimum_index_compatibility_version']

Indicates the minimum compatible index version which is supported.

TEXT

version['minimum_wire_compatibility_version']

Indicates the minimum compatible wire protocol version which is supported.

TEXT

cluster_state_version

Column Name

Description

Return Type

cluster_state_version

The current version of the cluster state. The cluster state is an immutable structure and that is recreated when a change is published.

BIGINT

fs

Column Name

Description

Return Type

fs

Utilization statistics about the file system.

OBJECT

fs['total']

Aggregated usage statistic of all disks on the host.

OBJECT

fs['total']['size']

Total size of all disks in bytes.

BIGINT

fs['total']['used']

Total used space of all disks in bytes.

BIGINT

fs['total']['available']

Total available space of all disks in bytes.

BIGINT

fs['total']['reads']

Total number of reads on all disks.

BIGINT

fs['total']['bytes_read']

Total size of reads on all disks in bytes.

BIGINT

fs['total']['writes']

Total number of writes on all disks.

BIGINT

fs['total']['bytes_written']

Total size of writes on all disks in bytes.

BIGINT

fs['disks']

Usage statistics of individual disks on the host.

ARRAY

fs['disks']['dev']

Device name

TEXT

fs['disks']['size']

Total size of the disk in bytes.

BIGINT

fs['disks']['used']

Used space of the disk in bytes.

BIGINT

fs['disks']['available']

Available space of the disk in bytes.

BIGINT

fs['data']

Information about data paths used by the node.

ARRAY

fs['data']['dev']

Device name

TEXT

fs['data']['path']

File path where the data of the node resides.

TEXT

thread_pools

Column Name

Description

Return Type

thread_pools

Usage statistics of Java thread pools.

ARRAY

thread_pools['name']

Name of the pool.

TEXT

thread_pools['active']

Number of currently running thread in the thread pool.

INTEGER

thread_pools['rejected']

Total number of rejected threads in the thread pool.

BIGINT

thread_pools['largest']

Largest number of threads that have ever simultaniously been in the pool.

INTEGER

thread_pools['completed']

Total number of completed thread in teh thread pool.

BIGINT

thread_pools['threads']

Size of the thread pool.

INTEGER

thread_pools['queue']

Number of thread currently in the queue.

INTEGER

os

Column Name

Description

Return Type

os

Operating system stats

OBJECT

os['uptime']

System uptime in milliseconds

Requires allowing system calls on Windows and macOS. See notes in Uptime limitations.

BIGINT

os['timestamp']

UNIX timestamp in millisecond resolution

BIGINT

os['cpu']

Information about CPU utilization

OBJECT

os['cpu']['used']

System CPU usage as percentage

SMALLINT

os['probe_timestamp']

Unix timestamp at the time of collection of the OS probe.

BIGINT

os['cgroup']

Information about Cgroups (Linux only)

OBJECT

os['cgroup']['cpuacct']

Information about CPU accounting

OBJECT

os['cgroup']['cpuacct']['control_group']

The path to the cpu accounting cgroup

TEXT

os['cgroup']['cpuacct']['usage_nanos']

The total CPU time (in nanoseconds) consumed by all tasks in this cgroup.

BIGINT

os['cgroup']['cpu']

Information about the CPU subsystem

OBJECT

os['cgroup']['cpu']['control_group']

The path to the cpu cgroup

TEXT

os['cgroup']['cpu']['cfs_period_micros']

The period of time (in microseconds) the cgroup access to the CPU gets reallocated.

BIGINT

os['cgroup']['cpu']['cfs_quota_micros']

The total amount of time (in microseconds) for which all tasks in the cgroup can run during one period (cfs_period_micros).

BIGINT

os['cgroup']['cpu']['num_elapsed_periods']

The nr. of period intervals (cfs_period_micros) that have elapsed.

BIGINT

os['cgroup']['cpu']['num_times_throttled']

The nr. of times tasks in the cgroup have been throttled.

BIGINT

os['cgroup']['cpu']['time_throttled_nanos']

The total time (in nanoseconds) for which tasks in the cgroup have been throttled.

BIGINT

os['cgroup']['mem']

Information about memory resources used by tasks in a cgroup.

OBJECT

os['cgroup']['mem']['control_group']

The path to the memory cgroup

TEXT

os['cgroup']['mem']['usage_bytes']

The total current memory usage by processes in the cgroup.

TEXT

os['cgroup']['mem']['limit_bytes']

The max. amount of user memory in the cgroup.

TEXT

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

os_info

Operating system information

OBJECT

os_info['available_processors']

Number of processors that are available in the JVM. This is usually equal to the number of cores of the CPU.

INTEGER

os_info['name']

Name of the operating system (ex: Linux, Windows, macOS)

TEXT

os_info['arch']

Name of the JVM architecture (ex: amd64, x86)

TEXT

os_info['version']

Version of the operating system

TEXT

os_info['jvm']

Information about the JVM (Java Virtual Machine)

OBJECT

os_info['jvm']['version']

The JVM version

TEXT

os_info['jvm']['vm_name']

The name of the JVM (eg. OpenJDK, Java Hotspot(TM) )

TEXT

os_info['jvm']['vm_vendor']

The vendor name of the JVM

TEXT

os_info['jvm']['vm_version']

The version of the JVM

TEXT

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

network

Statistics about network activity on the host.

OBJECT

network['probe_timestamp']

Unix timestamp at the time of collection of the network probe.

BIGINT

network['tcp']

TCP network activity on the host.

OBJECT

network['tcp']['connections']

Information about TCP network connections.

OBJECT

network['tpc']['connections']['initiated']

Total number of initiated TCP connections.

BIGINT

network['tpc']['connections']['accepted']

Total number of accepted TCP connections.

BIGINT

network['tpc']['connections']['curr_established']

Total number of currently established TCP connections.

BIGINT

network['tcp']['connections']['dropped']

Total number of dropped TCP connections.

BIGINT

network['tcp']['connections']['embryonic_dropped']

Total number of TCP connections that have been dropped before they were accepted.

BIGINT

network['tcp']['packets']

Information about TCP packets.

OBJECT

network['tpc']['packets']['sent']

Total number of TCP packets sent.

BIGINT

network['tcp']['packets']['received']

Total number of TCP packets received.

BIGINT

network['tpc']['packets']['retransmitted']

Total number of TCP packets retransmitted due to an error.

BIGINT

network['tcp']['packets']['errors_received']

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.

BIGINT

network['tcp']]['packets']['rst_sent']

Total number of RST packets sent due to left unread data in queue when socket is closed. See tools.ietf.org.

BIGINT

connections

Column Name

Description

Return Type

http

Number of connections established via HTTP

OBJECT

http['open']

The currently open connections established via HTTP

BIGINT

http['total']

The total number of connections that have been established via HTTP over the life time of a CrateDB node

BIGINT

psql

Number of connections established via Postgres protocol

OBJECT

psql['open']

The currently open connections established via Postgres protocol

BIGINT

psql['total']

The total number of connections that have been established via Postgres protocol over the life time of a CrateDB node

BIGINT

transport

Number of connections established via Transport protocol

OBJECT

transport['open']

The currently open connections established via Transport protocol

BIGINT

process

Column Name

Description

Return Type

process

Statistics about the CrateDB process.

OBJECT

process['open_file_descriptors']

Number of currently open file descriptors used by the CrateDB process.

BIGINT

process['max_open_file_descriptors']

The maximum number of open file descriptors CrateDB can use.

BIGINT

process['probe_timestamp']

The system UNIX timestamp at the moment of the probe collection.

BIGINT

process['cpu']

Information about the CPU usage of the CrateDB process.

OBJECT

process['cpu']['percent']

The CPU usage of the CrateDB JVM process given in percent.

SMALLINT

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

id

The unique check ID.

INTEGER

node_id

The unique node ID.

TEXT

severity

The level of severity. The higher the value of the field the higher severity.

INTEGER

description

The description message for the setting check.

TEXT

passed

The flag determines whether the check for the setting has passed.

BOOLEAN

acknowledged

The flag determines whether the check for this setting has been acknowledged by the user in order to ignored the value of passed column. This column can be updated.

BOOLEAN

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_nodes' mus... |
|  2 | ...         | The value of the cluster setting 'gateway.recover_after_nodes... |
|  3 | ...         | If any of the "expected nodes" recovery settings are set, the... |
|  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... |
+----+---------...-+--------------------------------------------------------------...-+
SELECT 6 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_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 nodes

The check for the gateway.expected_nodes setting checks that the number of nodes that should be waited for the immediate cluster state recovery. This value must be equal to the maximum number of data and master nodes in the cluster.

Recovery after nodes

The check for the gateway.recover_after_nodes verifies that the number of started nodes before the cluster starts must be greater than the half of the expected number of nodes and equal to or less than number of nodes in the cluster.

(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_nodes is set, then gateway.recover_after_time must not be set to 0s, otherwise the gateway.recover_after_nodes setting wouldn’t have any effect.

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.

Shards

The table sys.shards contains real-time statistics for all shards of all (non-system) tables.

Table schema

Column Name

Description

Return Type

node

Information about the node the shard is located at.

OBJECT

node['name']

The name of the node the shard is located at.

TEXT

node['id']

The id of the node the shard is located at.

TEXT

blob_path

Path to the directory which contains the blob files of the shard, or null if the shard is not a blob shard.

TEXT

id

The shard id. This shard id is managed by the system, ranging from 0 up to the number of configured shards of the table.

INTEGER

min_lucene_version

Shows the oldest Lucene segment version used in this shard.

TEXT

num_docs

The total amount of documents within a shard.

BIGINT

oprhan_partition

True if this shard belongs to an orphaned partition which doesn’t belong to any table anymore.

BOOLEAN

partition_ident

The partition ident of a partitioned table. Empty for non-partitioned tables.

TEXT

path

Path to the shard directory on the filesystem. This directory contains state and index files.

TEXT

primary

Indicates if this shard is the primary shard.

BOOLEAN

recovery

Recovery statistics for a shard.

OBJECT

recovery['files']

File recovery statistics

OBJECT

recovery['files']['percent']

Percentage of files already recovered.

REAL

recovery['files']['recovered']

Number of files recovered in the shard. Includes both existing and reused files.

INTEGER

recovery['files']['reused']

Total number of files reused from a local copy while recovering the shard.

INTEGER

recovery['files']['used']

Total number of files in the shard.

INTEGER

recovery['size']

Recovery statistics for the shard in bytes

OBJECT

recovery['size']['percent']

Percentage of bytes already recovered

REAL

recovery['size']['recovered']

Number of bytes recovered. Includes both existing and re-used bytes.

BIGINT

recovery['size']['reused']

Number of bytes re-used from a local copy while recovering the shard.

BIGINT

recovery['size']['used']

Total number of bytes in the shard.

BIGINT

recovery['stage']

Recovery stage:

  • init: Recovery has not started

  • index: Reading the Lucene index meta-data and copying bytes from source to destination

  • start: Starting the engine, opening the index for use

  • translog: Replaying transaction log

  • finalize: Cleanup

  • done: Complete

TEXT

recovery['total_time']

Returns elapsed time from the start of the shard recovery.

BIGINT

recovery['type']

Recovery type:

  • gateway

  • snapshot

  • replica

  • relocating

TEXT

relocating_node

The id of the node to which the shard is getting relocated to.

TEXT

routing_state

The current state of the shard in the routing table. Possible states are:

  • UNASSIGNED

  • INITIALIZING

  • STARTED

  • RELOCATING

TEXT

schema_name

The schema name of the table the shard belongs to

TEXT

size

The current size in bytes. This value is cached for a short period and may return slightly outdated values.

BIGINT

state

The current state of the shard. Possible states are:

  • CREATED

  • RECOVERING

  • POST_RECOVERY

  • STARTED

  • RELOCATED

  • CLOSED

  • INITIALIZING

  • UNASSIGNED

TEXT

closed

The state of the table associated with the shard.

BOOLEAN

table_name

The name of the table this shard belongs to

TEXT

seq_no_stats

Contains information about internal sequence numbering and checkpoints for these sequence numbers.

OBJECT

seq_no_stats['max_seq_no']

The highest sequence number that has been issued so far on the shard.

BIGINT

seq_no_stats['local_checkpoint']

The highest sequence number for which all lower sequence number of been processed on this shard. Due to concurrent indexing this can be lower than max_seq_no.

BIGINT

seq_no_stats['global_checkpoint']

The highest sequence number for which the local shard can guarantee that all lower sequence numbers have been processed on all active shard copies.

BIGINT

translog_stats

Contains information for the translog of the shard.

OBJECT

translog_stats['size']

The current size of the translog file in bytes.

BIGINT

translog_stats['uncommitted_size']

The size in bytes of the translog that has not been committed to Lucene yet.

BIGINT

translog_stats['number_of_operations']

The number of operations recorded in the translog.

INTEGER

translog_stats['uncommitted_operations']

The number of operations in the translog which have not been committed to Lucene yet.

INTEGER

retention_leases

Versioned collection of retention leases.

OBJECT

Note

The sys.shards table is subject to Shard table permissions.

Example

For example, you can query shards like this:

cr> select schema_name as schema,
...   table_name as t,
...   id,
...   partition_ident as p_i,
...   num_docs as docs,
...   primary,
...   relocating_node as r_n,
...   routing_state as r_state,
...   state,
...   orphan_partition as o_p
... from sys.shards where table_name = 'locations' and id = 1;
+--------+-----------+----+-----+------+---------+------+---------+---------+-------+
| schema | t         | id | p_i | docs | primary | r_n  | r_state |  state  | o_p   |
+--------+-----------+----+-----+------+---------+------+---------+---------+-------+
| doc    | locations |  1 |     |    8 | TRUE    | NULL | STARTED | STARTED | FALSE |
+--------+-----------+----+-----+------+---------+------+---------+---------+-------+
SELECT 1 row in set (... sec)

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

segment_name

Name of the segment, derived from the segment generation and used internally to create file names in the directory of the shard.

TEXT

shard_id

ID of the effected shard.

INTEGER

table_schema

Schema name of the table of the shard.

TEXT

table_name

Table name of the shard.

TEXT

partition_ident

The partition ident of a partitioned table. Empty for non-partitioned tables.

TEXT

node

Information about the node the shard is located at.

OBJECT

node['name']

The name of the node the shard is located at.

TEXT

node['id']

The id of the node the shard is located at.

TEXT

generation

Generation number of the segment, increments for each segment written.

LONG

num_docs

Number of non-deleted lucene documents in this segment.

INTEGER

deleted_docs

Number of deleted lucene documents in this segment.

INTEGER

size

Disk space used by the segment in bytes.

LONG

memory

Segment data stored in memory for efficient search, -1 if it is unavailable.

LONG

committed

Indicates if the segments are synced to disk. Segments that are synced can survive a hard reboot.

BOOLEAN

primary

Describes if this segment is part of a primary shard.

BOOLEAN

search

Indicates if the segment is searchable. If false, the segment has most likely been written to disk but needs a refresh to be searchable.

BOOLEAN

version

Version of Lucene used to write the segment.

TEXT

compound

If true, Lucene merges all files from the segment into a single file to save file descriptors.

BOOLEAN

attributes

Contains information about whether high compression was enabled.

OBJECT

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

id

The job UUID.

This job ID is generated by the sytem.

TEXT

node

Information about the node that created the job.

OBJECT

node['id']

The id of the node.

TEXT

node['name']

The name of the node.

TEXT

started

The point in time when the job started.

TIMESTAMP WITH TIME ZONE

stmt

Shows the data query or manipulation statement represented by this job.

TEXT

username

The user who is executing the statement.

TEXT

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

node

An object containing the id and name of the node on which the metrics have been sampled.

OBJECT

classification

An object containing the statement classification.

OBJECT

classification['type']

The general type of the statement. Types are: INSERT, SELECT, UPDATE, DELETE, COPY, DDL, and MANAGEMENT.

TEXT

classification['labels']

Labels are only available for certain statement types that can be classified more accurately than just by their type.

TEXT_ARRAY

total_count

Total number of queries executed

BIGINT

failed_count

Total number of queries that failed to complete successfully.

BIGINT

sum_of_durations

Sum of durations in ms of all executed queries per statement type.

BIGINT

stdev

The standard deviation of the query latencies

DOUBLE PRECISION

mean

The mean query latency in ms

DOUBLE PRECISION

max

The maximum query latency in ms

BIGINT

min

The minimum query latency in ms

BIGINT

percentiles

An object containing different percentiles

OBJECT

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 ALL

  • Get for the left SELECT

  • Collect 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

id

The operation UUID.

This operation ID is generated by the sytem.

TEXT

job_id

The job id this operation belongs to.

TEXT

name

The name of the operation.

TEXT

node

Information about the node that created the operation.

OBJECT

node['id']

The id of the node.

TEXT

node['name']

The name of the node.

TEXT

started

The point in time when the operation started.

TIMESTAMP WITH TIME ZONE

used_bytes

Currently loaded amount of data by the operation.

BIGINT

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

id

The job ID.

TEXT

ended

The point in time when the job finished.

TIMESTAMP WITH TIME ZONE

error

If the job encountered an error, this will hold the error message.

TEXT

started

The point in time when the job started.

TIMESTAMP WITH TIME ZONE

stmt

Shows the data query or manipulation statement executed by the job.

TEXT

username

The user who executed the statement.

TEXT

classification

An object containing the statement classification.

OBJECT

classification['type']

The general type of the statement. Types are: INSERT, SELECT, UPDATE, DELETE,``COPY``, DDL, and MANAGEMENT.

TEXT

classification['labels']

Labels are only available for certain statement types that can be classified more accurately than just by their type.

TEXT_ARRAY

node

Information about the node that created the job.

OBJECT

node['id']

The id of the node.

TEXT

node['name']

The name of the node.

TEXT

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

id

The operation ID.

TEXT

job_id

The job id.

TEXT

ended

The point in time when the operation finished.

TIMESTAMP WITH TIME ZONE

error

If the operation encountered an error, this will hold the error message.

TEXT

name

The name of the operation.

TEXT

started

The point in time when the operation started.

TIMESTAMP WITH TIME ZONE

used_bytes

The amount of data loaded by the operation.

BIGINT

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

id

The unique check id.

INTEGER

severity

The level of severity. The higher the value of the field the higher severity.

INTEGER

description

The description message for the setting check.

TEXT

passed

The flag determines whether the check for the setting has passed.

BOOLEAN

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:

../_images/cluster-checks-critical.png

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
  1. 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,                                       |
    |    "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)
    
  2. 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)
    
  3. Copy the data:

    cr> INSERT INTO rx.tmp_metrics (id, temperature) (SELECT id, temperature FROM rx.metrics);
    INSERT OK, 2 rows affected (... sec)
    
  4. Swap the tables:

    cr> ALTER CLUSTER SWAP TABLE rx.tmp_metrics TO rx.metrics;
    ALTER OK, 1 row affected  (... sec)
    
  5. 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'] |
    +--------------------+
    | 4.6.6              |
    +--------------------+
    SELECT 1 row in set (... sec)
    
  6. 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

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

table_name

The table name.

TEXT

table_schema

The schema of the table.

TEXT

partition_ident

The ident of the partition. NULL for non-partitioned tables.

TEXT

health

The health label. Can be RED, YELLOW or GREEN.

TEXT

severity

The health as a smallint value. Useful when ordering on health.

SMALLINT

missing_shards

The number of not assigned or started shards.

INTEGER

underreplicated_shards

The number of shards which are not fully replicated.

INTEGER

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

RED

At least one primary shard is missing (primary shard not started or unassigned).

YELLOW

At least one shard is underreplicated (replica shard not started or unassigned).

GREEN

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

name

The repository name

TEXT

type

The type of the repository determining how and where the repository stores its snapshots.

TEXT

settings

The configuration settings the repository has been created with. The specific settings depend on the repository type, see CREATE REPOSITORY.

OBJECT

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

name

The name of the snapshot

TEXT

repository

The name of the repository that contains this snapshot.

TEXT

concrete_indices

Contains the names of all tables and partitions that are contained in this snapshot how they are represented as ES index names.

ARRAY(TEXT)

tables

Contains the fully qualified names of all tables within the snapshot.

ARRAY(TEXT)

started

The point in time when the creation of the snapshot started. Changes made after that are not stored in this snapshot.

TIMESTAMP WITH TIME ZONE

finished

The point in time when the snapshot creation finished.

TIMESTAMP WITH TIME ZONE

state

The current state of the snapshot. One of: IN_PROGRESS, SUCCESS, PARTIAL, or FAILED.

TEXT

version

An internal version this snapshot was created with.

TEXT

failures

A list of failures that occurred while taking the snapshot. If taking the snapshot was successful this is empty.

ARRAY(TEXT)

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

concrete_indices entry

doc.my_table

my_table

my_schema.my_table

my_schema.my_table

doc.parted_table (value=null)

.partitioned.my_table.0400

my_schema.parted_table (value=null)

my_schema..partitioned.my_table.0400

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.

pg_stats schema

Name

Description

Type

id

The UUID of the restore snapshot operation.

TEXT

repository

The name of the repository that contains the snapshot.

TEXT

snapshot

The name of the snapshot.

TEXT

state

The current state of the snapshot restore operations. Possible states are: INIT, STARTED, SUCCESS, and FAILURE.

TEXT

shards['table_schema']

The schema name of the table of the shard.

TEXT

shards['table_name']

The table name of the shard.

TEXT

shards['partition_ident']

The identifier of the partition of the shard. NULL if the is not partitioned.

TEXT

shards['shard_id']

The ID of the shard.

INTEGER

shards['state']

The restore state of the shard. Possible states are: INIT, STARTED, SUCCESS, and FAILURE.

TEXT

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

name

The name of the database user.

TEXT

superuser

BOOLEAN flag to indicate whether the user is a superuser.

BOOLEAN

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

table_schema

Schema name of the table of the shard.

TEXT

table_name

Table name of the shard.

TEXT

partition_ident

Identifier of the partition of the shard. NULL if the table is not partitioned.

TEXT

shard_id

ID of the effected shard.

INTEGER

node_id

ID of the node on which the shard resides. NULL if the shard is unassigned.

TEXT

primary

Whether the shard is a primary shard.

BOOLEAN

current_state

Current state of the shard. Possible states are: UNASSIGNED, INITIALIZING, STARTED, RELOCATING

TEXT

explanation

Explanation why the shard cannot be allocated, moved or rebalanced.

TEXT

decisions

A list of decisions that describe in detail why the shard in the current state.

ARRAY

decisions['node_id']

ID of the node of the decision.

TEXT

decisions['node_name']

Name of the node of the decision.

TEXT

decisions['explanations']

Detailed list of human readable explanations why the node decided whether to allocate or rebalance the shard. Returns NULL if there is no need to rebalance the shard.

ARRAY

Note

The sys.allocations table is subject to Shard table permissions.

Shard table permissions

Accessing tables that return shards (sys.shards, sys.allocations) is subjected to the same privileges constraints as the other tables. Namely, in order to query them, the connected user needs to have the DQL privilege on that particular table, either directly or inherited from the SCHEMA or CLUSTER (for more information on privileges inheritance see Hierarchical Inheritance of Privileges).

However, being able to query shard returning system tables will not allow the user to retrieve all the rows in the table, as they may contain information related to tables, which the connected user does not have any privileges for. The only rows that will be returned will be the ones the user is allowed to access.

For example, if the user john has any privilege on the doc.books table but no privilege at all on doc.locations, when john issues a SELECT * FROM sys.shards statement, the shards information related to the doc.locations table will not be returned.

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.

pg_stats schema

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.

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