MatrixOne System Database and Tables

MatrixOne system database and tables are where MatrixOne stores system information. We can access the system information through them. MatrixOne creates 6 system databases at initialization: mo_catalog, information_schema, system_metrcis, system, mysql, and mo_task. mo_task is under development and have no direct impact on users. The other system databases and table functions are described in this document.

The system can only modify system databases and tables, and users can only read from them.

mo_catalog database

mo_catalog stores the metadata of MatrixOne objects: databases, tables, columns, system variables, accounts, users, and roles.

Start with MatrixOne 0.6 has introduced the concept of multi-account, the default sys account and other accounts have slightly different behaviors. The system table mo_account, which serves the multi-tenancy management, is only visible for the sys account; the other accounts don't see this table.

mo_database table

column	type	comments
dat_id	bigint unsigned	Primary key ID
datname	varchar(100)	Database name
dat_catalog_name	varchar(100)	Database catalog name, default as def
dat_createsql	varchar(100)	Database creation SQL statement
owner	int unsigned	Role id
creator	int unsigned	User id
created_time	timestamp	Create time
account_id	int unsigned	Account id
dat_type	varchar(23)	Database type, common library or subscription library

mo_tables table

column	type	comments
rel_id	bigint unsigned	Primary key, table ID
relname	varchar(100)	Name of the table, index, view, and so on.
reldatabase	varchar(100)	The database that contains this relation. reference mo_database.datname
reldatabase_id	bigint unsigned	The database id that contains this relation. reference mo_database.datid
relpersistence	varchar(100)	p = permanent table, t = temporary table
relkind	varchar(100)	r = ordinary table, e = external table, i = index, S = sequence, v = view, m = materialized view
rel_comment	varchar(100)
rel_createsql	varchar(100)	Table creation SQL statement
created_time	timestamp	Create time
creator	int unsigned	Creator ID
owner	int unsigned	Creator's default role id
account_id	int unsigned	Account id
partitioned	blob	Partition by statement
partition_info	blob	the information of partition
viewdef	blob	View definition statement
constraint	varchar(5000)	Table related constraints
catalog_version	INT UNSIGNED(0)	Version number of the system table

mo_columns table

column	type	comments
att_uniq_name	varchar(256)	Primary Key. Hidden, composite primary key, format is like "${att_relname_id}-${attname}"
account_id	int unsigned	accountID
att_database_id	bigint unsigned	databaseID
att_database	varchar(256)	database Name
att_relname_id	bigint unsigned	table id
att_relname	varchar(256)	The table this column belongs to.(references mo_tables.relname)
attname	varchar(256)	The column name
atttyp	varchar(256)	The data type of this column (zero for a dropped column).
attnum	int	The number of the column. Ordinary columns are numbered from 1 up.
att_length	int	bytes count for the type.
attnotnull	tinyint(1)	This represents a not-null constraint.
atthasdef	tinyint(1)	This column has a default expression or generation expression.
att_default	varchar(1024)	default expression
attisdropped	tinyint(1)	This column has been dropped and is no longer valid. A dropped column is still physically present in the table, but is ignored by the parser and so cannot be accessed via SQL.
att_constraint_type	char(1)	p = primary key constraint, n=no constraint
att_is_unsigned	tinyint(1)	unsigned or not
att_is_auto_increment	tinyint(1)	auto increment or not
att_comment	varchar(1024)	comment
att_is_hidden	tinyint(1)	hidden or not
attr_has_update	tinyint(1)	This columns has update expression
attr_update	varchar(1024)	update expression
attr_is_clusterby	tinyint(1)	Whether this column is used as the cluster by keyword to create the table

mo_table_partitions table

column	type	comments
table_id	BIGINT UNSIGNED(64)	The ID of the current partitioned table.
database_id	BIGINT UNSIGNED(64)	The ID of the database to which the current partitioned table belongs.
number	SMALLINT UNSIGNED(16)	The current partition number. All partitions are indexed in the order they are defined, with 1 assigned to the first partition.
name	VARCHAR(64)	The name of the partition.
partition_type	VARCHAR(50)	Stores the partition type information for the table. For partitioned tables, the values can be "KEY", "LINEAR_KEY", "HASH", "LINEAR_KEY_51", "RANGE", "RANGE_COLUMNS", "LIST", "LIST_COLUMNS". For non-partitioned tables, the value is an empty string. Note: MatrixOne does not currently support RANGE and LIST partitioning.
partition_expression	VARCHAR(2048)	The expression for the partitioning function used in the CREATE TABLE or ALTER TABLE statement that created the partitioned table's partitioning scheme.
description_utf8	TEXT(0)	This column is used for RANGE and LIST partitions. For a RANGE partition, it contains the value set in the partition's VALUES LESS THAN clause, which can be an integer or MAXVALUE. For a LIST partition, this column contains the values defined in the partition's VALUES IN clause, which is a comma-separated list of integer values. For partitions with partition_type other than RANGE or LIST, this column is always NULL. Note: MatrixOne does not currently support RANGE and LIST partitioning, so this column is NULL.
comment	VARCHAR(2048)	The text of the comment, if the partition has one. Otherwise, this value is empty.
options	TEXT(0)	Partition options information, currently set to NULL.
partition_table_name	VARCHAR(1024)	The name of the subtable corresponding to the current partition.

mo_account table (Only visible for sys account)

column	type	comments
account_id	int unsigned	account id, primary key
account_name	varchar(100)	account name
status	varchar(100)	open/suspend
created_time	timestamp	create time
comments	varchar(256)	comment
suspended_time	TIMESTAMP	Time of the account's status is changed
version	bigint unsigned	the version status of the current account

mo_role table

column	type	comments
role_id	int unsigned	role id, primary key
role_name	varchar(100)	role name
creator	int unsigned	user_id
owner	int unsigned	MOADMIN/ACCOUNTADMIN ownerid
created_time	timestamp	create time
comments	text	comment

mo_user table

column	type	comments
user_id	int	user id, primary key
user_host	varchar(100)	user host address
user_name	varchar(100)	user name
authentication_string	varchar(100)	authentication string encrypted with password
status	varchar(8)	open,locked,expired
created_time	timestamp	user created time
expired_time	timestamp	user expired time
login_type	varchar(16)	ssl/password/other
creator	int	the creator id who created this user
owner	int	the admin id for this user
default_role	int	the default role id for this user

mo_user_grant table

column	type	comments
role_id	int unsigned	ID of the authorized role, associated primary key
user_id	int unsigned	Obtain the user ID of the authorized role and associate the primary key
granted_time	timestamp	granted time
with_grant_option	bool	Whether to allow an authorized user to license to another user or role

mo_role_grant table

column	type	comments
granted_id	int	the role id being granted, associated primary key
grantee_id	int	the role id to grant others, associated primary key
operation_role_id	int	operation role id
operation_user_id	int	operation user id
granted_time	timestamp	granted time
with_grant_option	bool	Whether to allow an authorized role to be authorized to another user or role

mo_role_privs table

column	type	comments
role_id	int	role id, associated primary key
role_name	varchar(100)	role name: accountadmin/public
obj_type	varchar(16)	object type: account/database/table, associated primary key
obj_id	bigint unsigned	object id, associated primary key
privilege_id	int	privilege id, associated primary key
privilege_name	varchar(100)	privilege name: the list of privileges
privilege_level	varchar(100)	level of privileges, associated primary key
operation_user_id	int unsigned	operation user id
granted_time	timestamp	granted time
with_grant_option	bool	If permission granting is permitted

mo_stages table

column	type	comments
stage_id	INT UNSIGNED(32)	data stage ID
stage_name	VARCHAR(64)	data stage name
url	TEXT(0)	Path to object storage (without authentication), path to file system
stage_credentials	TEXT(0)	Authentication information, encrypted and saved
stage_status	VARCHAR(64)	ENABLED/DISABLED Default: DISABLED
created_time	TIMESTAMP(0)	creation time
comment	TEXT(0)	comment

mo_user_defined_function table

column	type	comments
function_id	INT(32)	ID of the function, primary key
name	VARCHAR(100)	the name of the function
owner	INT UNSIGNED(32)	ID of the role who created the function
args	TEXT(0)	Argument list for the function
rettype	VARCHAR(20)	return type of the function
body	TEXT(0)	function body
language	VARCHAR(20)	language used by the function
db	VARCHAR(100)	database where the function is located
definer	VARCHAR(50)	name of the user who defined the function
modified_time	TIMESTAMP(0)	time when the function was last modified
created_time	TIMESTAMP(0)	creation time of the function
type	VARCHAR(10)	type of function, default FUNCTION
security_type	VARCHAR(10)	security processing method, uniform value DEFINER
comment	VARCHAR(5000)	Create a comment for the function
character_set_client	VARCHAR(64)	Client character set: utf8mb4
collation_connection	VARCHAR(64)	Connection sort: utf8mb4_0900_ai_ci
database_collation	VARCHAR(64)	Database connection collation: utf8mb4_0900_ai_ci

mo_mysql_compatbility_mode table

column	type	comments
configuration_id	INT(32)	Configuration item id, an auto-increment column, used as a primary key to distinguish different configurations
account_name	VARCHAR(300)	The name of the tenant where the configuration is located
dat_name	VARCHAR(5000)	The name of the database where the configuration is located
configuration	JSON(0)	Configuration content, saved in JSON format

mo_pubs table

column	type	comments
pub_name	VARCHAR(64)	publication name
database_name	VARCHAR(5000)	The name of the published data
database_id	BIGINT UNSIGNED(64)	ID of the publishing database, corresponding to dat_id in the mo_database table
all_table	BOOL(0)	Whether the publishing library contains all tables in the database corresponding to database_id
all_account	BOOL(0)	Whether all accounts can subscribe to the library
table_list	TEXT(0)	When it is not all table, publish the list of tables contained in the library, and the table name corresponds to the table under the database corresponding to database_id
account_list	TEXT(0)	Account list that is allowed to subscribe to the publishing library when it is not all accounts
created_time	TIMESTAMP(0)	Time when the release repository was created
owner	INT UNSIGNED(32)	The role ID corresponding to the creation of the release library
creator	INT UNSIGNED(32)	The ID of the user who created the release library
comment	TEXT(0)	Remarks for creating a release library

mo_indexes table

column	type	comments
id	BIGINT UNSIGNED(64)	index ID
table_id	BIGINT UNSIGNED(64)	ID of the table where the index resides
database_id	BIGINT UNSIGNED(64)	ID of the database where the index resides
name	VARCHAR(64)	name of the index
type	VARCHAR(11)	The type of index, including primary key index (PRIMARY), unique index (UNIQUE), secondary index (MULTIPLE)
is_visible	TINYINT(8)	Whether the index is visible, 1 means visible, 0 means invisible (currently all MatrixOne indexes are visible indexes)
hidden	TINYINT(8)	Whether the index is hidden, 1 is a hidden index, 0 is a non-hidden index
comment	VARCHAR(2048)	Comment information for the index
column_name	VARCHAR(256)	The column name of the constituent columns of the index
ordinal_position	INT UNSIGNED(32)	Column ordinal in index, starting from 1
options	TEXT(0)	options option information for index
index_table_name	VARCHAR(5000)	The table name of the index table corresponding to the index, currently only the unique index contains the index table

system_metrics database

system_metrics collect the status and statistics of SQL statements, CPU & memory resource usage.

system_metrics tables have more or less same column types, fields in these tables are described as follows:

• collecttime:Collection time

• value: the value of the collecting metric

• node: the MatrixOne node uuid

• role: the MatrixOne node role, can be CN, TN or LOG.
• account: default as "sys", the account who fires the SQL request.
• type:SQL type, can be select, insert, update, delete, other types.

metric table

Column	Type	Comment
metric_name	VARCHAR(128)	metric name, like: sql_statement_total, server_connections, process_cpu_percent, sys_memory_used, ..
collecttime	DATETIME	metric data collect time
value	DOUBLE	metric value
node	VARCHAR(36)	MatrixOne node uuid
role	VARCHAR(32)	MatrixOne node role
account	VARCHAR(128)	account name, default "sys"
type	VARCHAR(32)	SQL type: like insert, select, update ...

The other tables are all views of the metric table:

• process_cpu_percent table: Process CPU busy percentage.
• process_open_fs table: Number of open file descriptors.
• process_resident_memory_bytes table: Resident memory size in bytes.
• server_connection table: Server connection numbers.
• sql_statement_errors table: Counter of sql statements executed with errors.
• sql_statement_total table: Counter of executed sql statement.
• sql_transaction_errors table: Counter of transactional statements executed with errors.
• sql_statement_hotspot table: records the most extended SQL query executed by each tenant within each minute. Only those SQL queries whose execution time does not exceed a certain aggregation threshold will be included in the statistics.
• sql_transaction_total table: Counter of transactional sql statement.
• sys_cpu_combined_percent table: System CPU busy percentage, average among all logical cores.
• sys_cpu_seconds_total table: System CPU time spent in seconds, normalized by number of cores
• sys_disk_read_bytes table: System disk read in bytes.
• sys_disk_write_bytes table: System disk write in bytes.
• sys_memory_available table: System memory available in bytes.
• sys_memory_used table: System memory used in bytes.
• sys_net_recv_bytes table: System net received in bytes.
• sys_net_sent_bytes table: System net sent in bytes.

system database

System database stores MatrixOne historical SQL statements, system logs, error information.

statement_info table

It records user and system SQL statement with detailed information.

Column	Type	Comments
statement_id	VARCHAR(36)	statement unique id
transaction_id	VARCHAR(36)	Transaction unique id
session_id	VARCHAR(36)	session unique id
account	VARCHAR(1024)	account name
user	VARCHAR(1024)	user name
host	VARCHAR(1024)	user client ip
database	VARCHAR(1024)	what database current session stay in
statement	TEXT	sql statement
statement_tag	TEXT	note tag in statement(Reserved)
statement_fingerprint	TEXT	note tag in statement(Reserved)
node_uuid	VARCHAR(36)	node uuid, which node gen this data
node_type	VARCHAR(64)	node type in MO, val in [TN, CN, LOG]
request_at	DATETIME	request accept datetime
response_at	DATETIME	response send datetime
duration	BIGINT	exec time, unit: ns
status	VARCHAR(32)	sql statement running status, enum: Running, Success, Failed
err_code	VARCHAR(1024)	error code
error	TEXT	error message
exec_plan	JSON	statement execution plan
rows_read	BIGINT	rows read total
bytes_scan	BIGINT	bytes scan total
stats	JSON	global stats info in exec_plan
statement_type	VARCHAR(1024)	statement type, val in [Insert, Delete, Update, Drop Table, Drop User, ...]
query_type	VARCHAR(1024)	query type, val in [DQL, DDL, DML, DCL, TCL]
role_id	BIGINT	role id
sql_source_type	TEXT	Type of SQL source internally generated by MatrixOne
aggr_count	BIGINT(64)	the number of statements aggregated
result_count	BIGINT(64)	the number of rows of sql execution results

rawlog table

It records very detailed system logs.

Column	Type	Comments
raw_item	VARCHAR(1024)	raw log item
node_uuid	VARCHAR(36)	node uuid, which node gen this data.
node_type	VARCHAR(64)	node type in MO, val in [TN, CN, LOG]
span_id	VARCHAR(16)	span unique id
statement_id	VARCHAR(36)	statement unique id
logger_name	VARCHAR(1024)	logger name
timestamp	DATETIME	timestamp of action
level	VARCHAR(1024)	log level, enum: debug, info, warn, error, panic, fatal
caller	VARCHAR(1024)	where it log, like: package/file.go:123
message	TEXT	log message
extra	JSON	log dynamic fields
err_code	VARCHAR(1024)	error log
error	TEXT	error message
stack	VARCHAR(4096)
span_name	VARCHAR(1024)	span name, for example: step name of execution plan, function name in code, ...
parent_span_id	VARCHAR(16)	parent span unique id
start_time	DATETIME
end_time	DATETIME
duration	BIGINT	exec time, unit: ns
resource	JSON	static resource information

The other 3 tables(log_info, span_info and error_info) are views of statement_info and rawlog table.

information_schema database

Information Schema provides an ANSI-standard way of viewing system metadata. MatrixOne also provides a number of custom information_schema tables, in addition to the tables included for MySQL compatibility.

Many INFORMATION_SCHEMA tables have a corresponding SHOW command. The benefit of querying INFORMATION_SCHEMA is that it is possible to join between tables.

Tables for MySQL compatibility

Table Name	Description
KEY_COLUMN_USAGE	Describes the key constraints of the columns, such as the primary key constraint.
COLUMNS	Provides a list of columns for all tables.
PROFILING	Provides some profiling information during SQL statement execution.
PROCESSLIST	Provides similar information to the command SHOW PROCESSLIST.
USER_PRIVILEGES	Summarizes the privileges associated with the current user.
SCHEMATA	Provides similar information to SHOW DATABASES.
CHARACTER_SETS	Provides a list of character sets the server supports.
TRIGGERS	Provides similar information to SHOW TRIGGERS.
TABLES	Provides a list of tables that the current user has visibility of. Similar to SHOW TABLES.
PARTITIONS	Provides information about table partitions.
VIEWS	Provides information about views in the database.
ENGINES	Provides a list of supported storage engines.
ROUTINES	Provides some information about stored procedures.
PARAMETERS	Provides information about stored procedures' parameters and return values ​​.
KEYWORDS	Provide information about keywords in the database; see Keywords for details.

CHARACTER_SETS table

The description of columns in the CHARACTER_SETS table is as follows:

• CHARACTER_SET_NAME: The name of the character set.
• DEFAULT_COLLATE_NAME The default collation name of the character set.
• DESCRIPTION The description of the character set.
• MAXLEN The maximum length required to store a character in this character set.

COLUMNS table

The description of columns in the COLUMNS table is as follows:

• TABLE_CATALOG: The name of the catalog to which the table with the column belongs. The value is always def.
• TABLE_SCHEMA: The name of the schema in which the table with the column is located.
• TABLE_NAME: The name of the table with the column.
• COLUMN_NAME: The name of the column.
• ORDINAL_POSITION: The position of the column in the table.
• COLUMN_DEFAULT: The default value of the column. If the explicit default value is NULL, or if the column definition does not include the default clause, this value is NULL.
• IS_NULLABLE: Whether the column is nullable. If the column can store null values, this value is YES; otherwise, it is NO.
• DATA_TYPE: The type of data in the column.
• CHARACTER_MAXIMUM_LENGTH: For string columns, the maximum length in characters.
• CHARACTER_OCTET_LENGTH: For string columns, the maximum length in bytes.
• NUMERIC_PRECISION: The numeric precision of a number-type column.
• NUMERIC_SCALE: The numeric scale of a number-type column.
• DATETIME_PRECISION: For time-type columns, the fractional seconds precision.
• CHARACTER_SET_NAME: The name of the character set of a string column.
• COLLATION_NAME: The name of the collation of a string column.
• COLUMN_TYPE: The column type.
• COLUMN_KEY: Whether this column is indexed. This field might have the following values:
  • Empty: This column is not indexed, or this column is indexed and is the second column in a multi-column non-unique index.
  • PRI: This column is the primary key or one of multiple primary keys.
  • UNI: This column is the first column of the unique index.
  • MUL: The column is the first column of a non-unique index, in which a given value is allowed to occur for multiple times.
• EXTRA: Any additional information of the given column.
• PRIVILEGES: The privilege that the current user has on this column.
• COLUMN_COMMENT: Comments contained in the column definition.
• GENERATION_EXPRESSION: For generated columns, this value displays the expression used to calculate the column value. For non-generated columns, the value is empty.
• SRS_ID: This value applies to spatial columns. It contains the column SRID value that indicates the spatial reference system for values stored in the column.

ENGINES table

The description of columns in the ENGINES table is as follows:

• ENGINES: The name of the storage engine.
• SUPPORT: The level of support that the server has on the storage engine.
• COMMENT: The brief comment on the storage engine.
• TRANSACTIONS: Whether the storage engine supports transactions.
• XA: Whether the storage engine supports XA transactions.
• SAVEPOINTS: Whether the storage engine supports savepoints.

PARTITIONS table

The description of columns in the PARTITIONS table is as follows:

• TABLE_CATALOG: The name of the catalog to which the table belongs. This value is always def.
• TABLE_SCHEMA: The name of the schema (database) to which the table belongs.
• TABLE_NAME: The name of the table containing the partition.
• PARTITION_NAME: The name of the partition.
• SUBPARTITION_NAME: If the PARTITIONS table row represents a subpartition, the name of subpartition; otherwise NULL.
• PARTITION_ORDINAL_POSITION: All partitions are indexed in the same order as they are defined, with 1 being the number assigned to the first partition. The indexing can change as partitions are added, dropped, and reorganized; the number shown is this column reflects the current order, taking into account any indexing changes.
• SUBPARTITION_ORDINAL_POSITION: Subpartitions within a given partition are also indexed and reindexed in the same manner as partitions are indexed within a table.
• PARTITION_METHOD: One of the values RANGE, LIST, HASH, LINEAR HASH, KEY, or LINEAR KEY. Note: MatrixOne does not currently support RANGE and LIST partitioning.
• SUBPARTITION_METHOD: One of the values HASH, LINEAR HASH, KEY, or LINEAR KEY.
• PARTITION_EXPRESSION: The expression for the partitioning function used in the CREATE TABLE or ALTER TABLE statement that created the table's current partitioning scheme.
• SUBPARTITION_EXPRESSION: This works in the same fashion for the subpartitioning expression that defines the subpartitioning for a table as PARTITION_EXPRESSION does for the partitioning expression used to define a table's partitioning. If the table has no subpartitions, this column is NULL.
• PARTITION_DESCRIPTION: This column is used for RANGE and LIST partitions. For a RANGE partition, it contains the value set in the partition's VALUES LESS THAN clause, which can be either an integer or MAXVALUE. For a LIST partition, this column contains the values defined in the partition's VALUES IN clause, which is a list of comma-separated integer values. For partitions whose PARTITION_METHOD is other than RANGE or LIST, this column is always NULL. Note: MatrixOne does not currently support RANGE and LIST partitioning.
• TABLE_ROWS: The number of table rows in the partition.
• AVG_ROW_LENGTH: The average length of the rows stored in this partition or subpartition, in bytes. This is the same as DATA_LENGTH divided by TABLE_ROWS.
• DATA_LENGTH: The total length of all rows stored in this partition or subpartition, in bytes; that is, the total number of bytes stored in the partition or subpartition.
• INDEX_LENGTH: The length of the index file for this partition or subpartition, in bytes.
• DATA_FREE: The number of bytes allocated to the partition or subpartition but not used.
• CREATE_TIME: The time that the partition or subpartition was created.
• UPDATE_TIME: The time that the partition or subpartition was last modified.
• CHECK_TIME: The last time that the table to which this partition or subpartition belongs was checked.
• CHECKSUM: The checksum value, if any; otherwise NULL.
• PARTITION_COMMENT: The text of the comment, if the partition has one. If not, this value is empty. The maximum length for a partition comment is defined as 1024 characters, and the display width of the PARTITION_COMMENT column is also 1024, characters to match this limit.
• NODEGROUP: This is the nodegroup to which the partition belongs.
• TABLESPACE_NAME: The name of the tablespace to which the partition belongs. The value is always DEFAULT.

PROCESSLIST table

Fields in the PROCESSLIST table are described as follows:

• ID: The ID of the user connection.
• USER: The name of the user who is executing PROCESS.
• HOST: The address that the user is connecting to.
• DB: The name of the currently connected default database.
• COMMAND: The command type that PROCESS is executing.
• TIME: The current execution duration of PROCESS, in seconds.
• STATE: The current connection state.
• INFO: The requested statement that is being processed.

SCHEMATA table

The SCHEMATA table provides information about databases. The table data is equivalent to the result of the SHOW DATABASES statement. Fields in the SCHEMATA table are described as follows:

• CATALOG_NAME: The catalog to which the database belongs.
• SCHEMA_NAME: The database name.
• DEFAULT_CHARACTER_SET_NAME: The default character set of the database.
• DEFAULT_COLLATION_NAME: The default collation of the database.
• SQL_PATH: The value of this item is always NULL.
• DEFAULT_TABLE_ENCRYPTION: defines the default encryption setting for databases and general tablespaces.

TABLES table

The description of columns in the TABLES table is as follows:

• TABLE_CATALOG: The name of the catalog which the table belongs to. The value is always def.
• TABLE_SCHEMA: The name of the schema which the table belongs to.
• TABLE_NAME: The name of the table.
• TABLE_TYPE: The type of the table. The base table type is BASE TABLE, the view table type is VIEW, and the INFORMATION_SCHEMA table type is SYSTEM VIEW.
• ENGINE: The type of the storage engine.
• VERSION: Version. The value is 10 by default.
• ROW_FORMAT: The row format. The value is Compact, Fixed, Dynamic, Compressed, Redundant.
• TABLE_ROWS: The number of rows in the table in statistics. For INFORMATION_SCHEMA tables, TABLE_ROWS is NULL.
• AVG_ROW_LENGTH: The average row length of the table. AVG_ROW_LENGTH = DATA_LENGTH / TABLE_ROWS.
• DATA_LENGTH: Data length. DATA_LENGTH = TABLE_ROWS * the sum of storage lengths of the columns in the tuple.
• MAX_DATA_LENGTH: The maximum data length. The value is currently 0, which means the data length has no upper limit.
• INDEX_LENGTH: The index length. INDEX_LENGTH = TABLE_ROWS * the sum of lengths of the columns in the index tuple.
• DATA_FREE: Data fragment. The value is currently 0.
• AUTO_INCREMENT: The current step of the auto- increment primary key.
• CREATE_TIME: The time at which the table is created.
• UPDATE_TIME: The time at which the table is updated.
• CHECK_TIME: The time at which the table is checked.
• TABLE_COLLATION: The collation of strings in the table.
• CHECKSUM: Checksum.
• CREATE_OPTIONS: Creates options.
• TABLE_COMMENT: The comments and notes of the table.

USER_PRIVILEGES table

The USER_PRIVILEGES table provides information about global privileges.

Fields in the USER_PRIVILEGES table are described as follows:

• GRANTEE: The name of the granted user, which is in the format of 'user_name'@'host_name'.
• TABLE_CATALOG: The name of the catalog to which the table belongs. This value is always def.
• PRIVILEGE_TYPE: The privilege type to be granted. Only one privilege type is shown in each row.
• IS_GRANTABLE: If you have the GRANT OPTION privilege, the value is YES; otherwise, the value is NO.

VIEW table

• TABLE_CATALOG: The name of the catalog the view belongs to. The value is def.
• TABLE_SCHEMA: The name of the database to which the view belongs.
• TABLE_NAME: The name of the view.
• VIEW_DEFINITION: The SELECT statement that provides the view definition. It contains most of what you see in the "Create Table" column generated by SHOW Create VIEW.
• CHECK_OPTION: The value of the CHECK_OPTION property. Values are NONE, CASCADE, or LOCAL.
• IS_UPDATABLE: Set a flag called the view updatable flag when CREATE VIEW; if UPDATE and DELETE (and similar operations) are legal for the view, the flag is set to YES(true). Otherwise, the flag is set to NO(false).
• DEFINER: The account of the user who created the view, in the format username@hostname.
• SECURITY_TYPE: View the SQL SECURITY attribute. Values ​​are DEFINER or INVOKER.
• CHARACTER_SET_CLIENT: The session value of the character_set_client system variable when the view was created.
• COLLATION_CONNECTION: The session value of the collation_connection system variable when the view was created.

STATISTICS Table

Obtain detailed information about database table indexes and statistics. For example, you can check whether an index is unique, understand the order of columns within an index, and estimate the number of unique values in an index.

• TABLE_CATALOG: The catalog name of the table (always 'def').
• TABLE_SCHEMA: The name of the database to which the table belongs.
• TABLE_NAME: The name of the table.
• NON_UNIQUE: Indicates whether the index allows duplicate values. If 0, the index is unique.
• INDEX_SCHEMA: The database name to which the index belongs.
• INDEX_NAME: The name of the index.
• SEQ_IN_INDEX: The position of the column within the index.
• COLUMN_NAME: The name of the column.
• COLLATION: The collation of the column.
• CARDINALITY: An estimated count of unique values in the index.
• SUB_PART: The length of the index part. For the entire column, this value is NULL.
• PACKED: Indicates whether compressed storage is used.
• NULLABLE: Indicates whether the column allows NULL values.
• INDEX_TYPE: The index type (e.g., BTREE, HASH, etc.).
• COMMENT: Comment information about the index.

mysql database

Grant system tables

These system tables contain grant information about user accounts and their privileges:

• user: user accounts, global privileges, and other non-privilege columns.
• db: database-level privileges.
• tables_priv: table-level privileges.
• columns_priv: column-level privileges.
• procs_priv: stored procedure and stored function privileges.