The metadatabase of a PolarDB-Xdatabase is an INFORMATION_SCHEMA database that is compatible with the metadatabase of MySQL. To query data in the metadatabase of a PolarDB-X database, you can execute SQL statements over a Java Database Connectivity (JDBC) connection.
Item in INFORMATION_SCHEMA | Compatible with MySQL |
SCHEMATA | Yes |
TABLES | Yes |
COLUMNS | Yes |
STATISTICS | Yes |
COLUMN_STATISTICS | Histograms are generated based on data that is processed by PolarDB-Xand is in a specific format supported by PolarDB-X. |
ENGINES | Yes |
KEYWORDS | Yes |
COLLATIONS | Yes |
TABLE_CONSTRAINTS | Yes |
PROCESSLIST | Yes |
SESSION_VARIABLES | Yes |
GLOBAL_VARIABLES | Yes |
INNODB_LOCKS | Yes |
INNODB_TRX | Yes |
INNODB_BUFFER_PAGE | Yes |
INNODB_BUFFER_POOL_STATS | Yes |
INNODB_BUFFER_PAGE_LRU | Yes |
INNODB_LOCK_WAITS | Yes |
USER_PRIVILEGES | Yes |
PARTITIONS | Only partitioned tables in the current PolarDB-Xdatabase have partitions. |
WORKLOAD | The hybrid transaction/analytical processing (HTAP) workloads on the current PolarDB-Xdatabase. |
GLOBAL_INDEXES | Global secondary indexes (GSIs) in the current PolarDB-Xdatabase. |
METADATA_LOCK | Information about metadata locks (MDLs) in the current PolarDB-Xdatabase. |
TABLE_GROUP | Information about table groups in the current PolarDB-Xdatabase. |
TABLE_DETAIL | Information about partitions in partitioned tables in the current PolarDB-Xdatabase. |
LOCALITY_INFO | Information about the locality of a database or table in the current PolarDB-Xdatabase. |
PHYSICAL_PROCESSLIST | Information about the SQL statements that are pushed down from compute nodes to data nodes of the current PolarDB-Xdatabase for execution. |
PLAN_CACHE | Information about caches of execution plans in the current PolarDB-Xdatabase. |
STATISTIC_TASK | Information about statistics tasks in the current PolarDB-Xdatabase. |
CCL_RULE | Information about concurrency control (CCL) rules in the current PolarDB-Xdatabase. |
CCL_TRIGGER | Information about CCL triggers in the current PolarDB-Xdatabase. |
STATEMENTS_SUMMARY | Summary of the current SQL statements that are executed on the current PolarDB database. |
STATEMENTS_SUMMARY_HISTORY | Summary of historical SQL statements that were executed on the current PolarDB database. |
SEQUENCES | Information about sequences in the current PolarDB-X database. |
SCHEMA_PRIVILEGES | No |
TABLE_PRIVILEGES | No |
INNODB_TEMP_TABLE_INFO | No |
INNODB_SYS_INDEXES | No |
INNODB_SYS_FIELDS | No |
INNODB_CMP_PER_INDEX_RESET | No |
INNODB_FT_DEFAULT_STOPWORD | No |
INNODB_FT_INDEX_TABLE | No |
INNODB_FT_INDEX_CACHE | No |
INNODB_SYS_TABLESPACES | No |
INNODB_METRICS | No |
INNODB_SYS_FOREIGN_COLS | No |
INNODB_CMPMEM | No |
INNODB_SYS_COLUMNS | No |
INNODB_SYS_FOREIGN | No |
INNODB_SYS_TABLESTATS | No |
INNODB_FT_CONFIG | No |
INNODB_SYS_VIRTUAL | No |
INNODB_CMP | No |
INNODB_FT_BEING_DELETED | No |
INNODB_CMP_PER_INDEX | No |
INNODB_CMPMEM_RESET | No |
INNODB_CMP_RESET | No |
INNODB_FT_DELETED | No |
INNODB_SYS_TABLES | No |
INNODB_SYS_DATAFILES | No |
PROFILING | No |
REFERENTIAL_CONSTRAINTS | No |
SESSION_STATUS | No |
TABLESPACES | No |
EVENTS | No |
TRIGGERS | No |
ROUTINES | No |
COLUMN_PRIVILEGES | No |
FILES | No |
KEY_COLUMN_USAGE | No |
OPTIMIZER_TRACE | No |
PARAMETERS | No |
CHARACTER_SETS | No |
COLLATION_CHARACTER_SET_APPLICABILITY | No |
PLUGINS | No |
SCHEMATA
The SCHEMATA table stores information about the current database. The SCHEMATA table contains the following columns:
CATALOG_NAME: the name of the catalog to which the database belongs. Valid value: def.
SCHEMA_NAME: the name of the database.
DEFAULT_CHARACTER_SET_NAME: the name of the default character set of the database.
DEFAULT_COLLATION_NAME: the name of the default collation of the database.
SQL_PATH: The value is NULL.
TABLES
The TABLES table stores information about database tables. The TABLES table contains the following columns:
TABLE_CATALOG: the name of the catalog to which the table belongs. Valid value: def.
TABLE_SCHEMA: the name of the database to which the table belongs.
TABLE_NAME: the name of the table.
ENGINE: the storage engine of the database.
VERSION: the version of the database.
ROW_FORMAT: the row format.
TABLE_ROWS: the estimated number of rows in the table.
AVG_ROW_LENGTH: the average length of values in rows.
DATA_LENGTH: the estimated size of the base table.
MAX_DATA_LENGTH: the maximum size of the table. Default value: NULL.
INDEX_LENGTH: the estimated size of the index table.
DATA_FREE: the idle storage space of the table.
AUTO_INCREMENT: the next AUTO_INCREMENT value.
CREATE_TIME: the point in time when the table was created.
UPDATE_TIME: the most recent point in time when the table was updated.
CHECK_TIME: the point in time when the table was checked. Valid value: NULL.
TABLE_COLLATION: the default collation of the table.
CHECKSUM: the CHECKSUM value of the table.
CREATE_OPTIONS: the options in the CREATE TABLE statement that is executed to create the table.
TABLE_COMMENT: the comments that are specified for the table.
COLUMNS
The COLUMNS table stores information about columns in the database. The COLUMNS table contains the following columns:
TABLE_CATALOG: the name of the catalog of the table to which the column belongs. Valid value: def.
TABLE_SCHEMA: the name of the database to which the column belongs.
TABLE_NAME: the name of the table to which the column belongs.
COLUMN_NAME: the name of the column.
ORDINAL_POSITION: the position of the column in the table.
COLUMN_DEFAULT: the default value in the column.
IS_NULLABLE: specifies whether NULL can be specified as a value in the column.
DATA_TYPE: the data type of the column. The value does not contain the precision of values in the column.
CHARACTER_MAXIMUM_LENGTH: the maximum length of a value in the column. Unit: characters.
CHARACTER_OCTET_LENGTH: the maximum length of a value in the column. Unit: bytes.
NUMERIC_PRECISION: the precision of numeric values in the column.
NUMERIC_SCALE: the scale of numeric values in the column.
DATETIME_PRECISION: the precision of datetime values in the column.
CHARACTER_SET_NAME: the name of the character set of the column.
COLLATION_NAME: the name of the collation of the column.
COLUMN_TYPE: the column type. The value includes the precision of values in the column.
COLUMN_KEY: the index on the column.
EXTRA: other information about the column.
PRIVILEGES: the permissions on the column.
COLUMN_COMMENT: the comments that are specified in the column definition.
GENERATION_EXPRESSION: the expression that is used to generate the column.
STATISTICS
The STATISTICS table stores information about indexes. The STATISTICS table contains the following columns:
TABLE_CATALOG: the name of the catalog of the base table to which the index belongs. Valid value: def.
TABLE_SCHEMA: the name of the schema of the base table to which the index belongs.
TABLE_NAME: the name of the base table to which the index belongs.
NON_UNIQUE: specifies whether the index is unique.
INDEX_SCHEMA: the name of the schema of the index table to which the index belongs.
INDEX_NAME: the name of the index.
SEQ_IN_INDEX: the sequence number of the index that is used to index the column.
COLUMN_NAME: the name of the column.
COLLATION: information about the column collation.
CARDINALITY: the cardinality of the column.
SUB_PART: the prefix of the index.
PACKED: information about the compressed index.
NULLABLE: specifies whether the column can contain NULL values.
INDEX_TYPE: the type of the index.
COMMENT: the comments of the index. The comments are not specified based on columns.
INDEX_COMMENT: the comments of the index.
STATEMENTS_SUMMARY and STATEMENTS_SUMMARY_HISTORY
The STATEMENTS_SUMMARY table stores summary information about SQL statements that are executed in the current statistical period. Summary information about SQL statements is collected based on SQL templates.
The STATEMENTS_SUMMARY_HISTORY table stores summary information about SQL statements that were executed in the historical statistical periods. Summary information about SQL statements is collected based on SQL templates.
By default, a statistical period is 30 minutes. The system can collect information about up to 1,000 SQL statements within each statistical period. The STATEMENTS_SUMMARY_HISTORY table contains information about SQL statements that are collected in the previous 24 statistical periods.
The STATEMENTS_SUMMARY table and STATEMENTS_SUMMARY_HISTORY table contains the following columns:
BEGIN_TIME: the start time of the statistical period.
SCHEMA: the name of the database.
SQL_TYPE: the type of the SQL statement.
TEMPLATE_ID: the ID of the SQL template.
PLAN_HASH: the hash value of the execution plan.
SQL_TEMPLATE: the SQL template.
COUNT: the number of executions.
ERROR_COUNT: the number of execution errors.
SUM_RESPONSE_TIME_MS: the total response time. Unit: ms.
AVG_RESPONSE_TIME_MS: the average response time. Unit: ms.
MAX_RESPONSE_TIME_MS: the maximum response time that is allowed. Unit: ms.
SUM_AFFECTED_ROWS: the total number of rows that are returned or updated. Unit: rows.
AVG_AFFECTED_ROWS: the average number of rows that are returned or updated. Unit: rows.
MAX_AFFECTED_ROWS: the maximum number of rows that can be returned or updated. Unit: rows.
SUM_TRANSACTION_TIME_MS: the total transaction time. Unit: ms.
Transaction time indicates the transaction duration until the execution of the statement is complete.
AVG_TRANSACTION_TIME_MS: the average transaction time. Unit: ms.
MAX_TRANSACTION_TIME_MS: the maximum transaction time that is allowed. Unit: ms.
SUM_BUILD_PLAN_CPU_TIME_MS: the total CPU time that is required to build execution plans. Unit: ms.
AVG_BUILD_PLAN_CPU_TIME_MS: the average CPU time that is required to build an execution plan. Unit: ms.
MAX_BUILD_PLAN_CPU_TIME_MS: the maximum CPU time that can be consumed to build an execution plan. Unit: ms.
SUM_EXEC_PLAN_CPU_TIME_MS: the total CPU time that is required to run execution plans. Unit: ms.
AVG_EXEC_PLAN_CPU_TIME_MS: the average CPU time that is required to run an execution plan. Unit: ms.
MAX_EXEC_PLAN_CPU_TIME_MS: the maximum CPU time that can be consumed to run an execution plan. Unit: ms.
SUM_PHYSICAL_TIME_MS: the total period of time that is required to push down SQL statements from compute nodes to data nodes for execution. Unit: ms.
AVG_PHYSICAL_TIME_MS: the average period of time that is required to push down an SQL statement from compute nodes to data nodes for execution. Unit: ms.
MAX_PHYSICAL_TIME_MS: the maximum period of time that can be consumed to push down an SQL statement from compute nodes to data nodes for execution. Unit: ms.
SUM_PHYSICAL_EXEC_COUNT: the total number of physical SQL executions.
AVG_PHYSICAL_EXEC_COUNT: the average number of physical SQL executions.
MAX_PHYSICAL_EXEC_COUNT: the maximum number of physical SQL executions.
SUM_PHYSICAL_FETCH_ROWS: the total number of rows that are retrieved by physical SQL queries.
AVG_PHYSICAL_FETCH_ROWS: the average number of rows that are retrieved by a physical SQL query.
MAX_PHYSICAL_FETCH_ROWS: the maximum number of rows that can be retrieved by a physical SQL query.
FIRST_SEEN: the point in time when the SQL template was collected for the first time.
LAST_SEEN: the point in time when the SQL template was collected the last time.
SQL_SAMPLE: the sample SQL statement.
PREV_TEMPLATE_ID: the ID of the template of the previous SQL statement.
PREV_SAMPLE_SQL: the previous sample SQL statement.
SAMPLE_TRACE_ID: the trace ID of the sample SQL statement.
WORKLOAD_TYPE: the type of workload. Valid values: TP and AP. TP indicates transactional processing and AP indicates analytical processing.
EXECUTE_MODE: the execution mode. Valid values:
NONE
CURSOR
TP_LOCAL
AP_LOCAL
MPP
For more information about INFORMATION_SCHEMA tables, visit the MySQL official website.