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. 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.

license

Column Name Description Return Type
license
The current CrateDB license information
or NULL on CrateDB CE.
OBJECT
license['expiry_date'] The Date/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": {...}, "gateway": {...}, "indices": {...}, "logger": [], "stats": {...}, "udc": {...}} |
+-----------------------------------------------------------------------------------------------------------------------------------...-+
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']['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             |
| settings['logger']['name']                                                        | text             |
| 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 specify the node name via your own custom configuration. 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 specify the ports via your own custom configuration. 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... |
|  8 | ...         | The JVM version with which CrateDB is running should be >= 11... |
+----+---------...-+--------------------------------------------------------------...-+
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_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, 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/less than number of nodes in the cluster.

(E / 2) < R <= E

where R is the number of recovery nodes, 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.

JVM version

The check for the JVM version checks if CrateDB is running under Java 11 or later. If not the check fails as we’re dropping support for earlier versions in future release. This is a low severity check that doesn’t require immediate action. But to be able to upgrade to future version the JVM should be upgraded eventually.

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 of a shard.

Recovery is the process of moving a shard to a different node or loading a shard from disk, e.g. during node startup or snapshot recovery.

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
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

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 enterprise edition is disabled or the user management module is not available, the username is represented 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... |
|  6 | Your CrateDB license is valid. Enjoy CrateDB!                    |
+----+--------------------------------------------------------------...-+
SELECT 3 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 there are tables that need to be recreated for compatibility with future major versions of CrateDB.

If you try to upgrade to the next major version of CrateDB with tables that have not been recreated, CrateDB will refuse to start.

To recreate a table, you have to create new tables, copy over the data and rename or remove the old table.

1) Use SHOW CREATE TABLE to get the schema required to create an empty copy of the table to recreate:

SHOW CREATE TABLE your_table;

2) Create a new temporary table, using the schema returned from SHOW CREATE TABLE:

CREATE TABLE tmp_your_table (...);
  1. Prevent inserts to the original table:

    ALTER TABLE your_table SET ("blocks.read_only" = true);
    
  2. Copy the data:

    INSERT INTO tmp_your_table (...) (SELECT ... FROM your_table);
    
  3. Swap the tables:

    ALTER CLUSTER SWAP TABLE tmp_your_table TO your_table;
    
  4. Confirm the new your_table contains all data and has the new version:

    SELECT count(*) FROM your_table;
    SELECT version FROM information_schema.tables where table_name = 'your_table';
    
  5. Drop the now obsolete old table:

    ALTER TABLE tmp_your_table SET ("blocks.read_only" = false);
    DROP TABLE tmp_your_table;
    

When all tables have been recreated, 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

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.

Note

This check is not active when running the CrateDB Community Edition as no license is supported.

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 |                 |        1 | locations  | doc          |                      0 |
| GREEN  |              0 |                 |        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)
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)

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. The table is only available in the CrateDB Enterprise Edition.

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.