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Syntax Changes in TDengine 3.0 /tdengine-reference/sql-manual/syntax-changes

Changes to SQL Basic Elements

# Element <div style={{width: 60}}>Difference Description
1 VARCHAR Added Alias for the BINARY type.
2 TIMESTAMP literal Added Supports the syntax TIMESTAMP 'timestamp format'.
3 _ROWTS pseudocolumn Added Represents the timestamp primary key. Alias for the _C0 pseudo column.
4 _IROWTS pseudocolumn Added Used to return the timestamp column corresponding to the interpolation result of the interp function.
5 INFORMATION_SCHEMA Added System database containing various SCHEMA definitions.
6 PERFORMANCE_SCHEMA Added System database containing operational information.
7 Continuous Query Deprecated Continuous queries are no longer supported. Various related syntax and interfaces are deprecated.
8 Mixed Operations Enhanced Comprehensive enhancement of mixed operations (scalar and vector operations mixed) in queries, all clauses of SELECT fully support mixed operations complying with syntax semantics.
9 Tag Operations Added In queries, tag columns can participate in various operations like normal columns, used in various clauses.
10 Timeline Clause and Time Functions for Supertable Queries Enhanced Without PARTITION BY, the data of the supertable will be merged into one timeline.
11 GEOMETRY Added Geometry type.

SQL Statement Changes

In TDengine, the following data types can be used in the data model of basic tables.

# Statement <div style={{width: 60}}>Difference Description
1 ALTER ACCOUNT Deprecated Was an enterprise feature in 2.x, no longer supported in 3.0. Syntax is temporarily retained, execution reports “This statement is no longer supported” error.
2 ALTER ALL DNODES Added Modify parameters of all DNODEs.
3 ALTER DATABASE Adjusted

Deprecated

  • QUORUM: The number of replica confirmations needed for writing. The default behavior in version 3.0 is strong consistency, and weak consistency is not supported.
  • BLOCKS: The number of memory blocks used by VNODE. Version 3.0 uses BUFFER to represent the size of the VNODE write memory pool.
  • UPDATE: Support mode for update operations. All databases in version 3.0 support partial column updates.
  • CACHELAST: Mode for caching the latest row of data. Replaced by CACHEMODEL in version 3.0.
  • COMP: Not supported for modification in version 3.0.

Added

  • CACHEMODEL: Indicates whether to cache recent data of subtables in memory.
  • CACHESIZE: Indicates the memory size for caching recent data of subtables.
  • WAL_FSYNC_PERIOD: Replaces the original FSYNC parameter.
  • WAL_LEVEL: Replaces the original WAL parameter.
  • WAL_RETENTION_PERIOD: Added in version 3.0.4.0, extra retention strategy for wal files, used for data subscription.
  • WAL_RETENTION_SIZE: Added in version 3.0.4.0, extra retention strategy for wal files, used for data subscription.

Adjusted

  • KEEP: Version 3.0 added support for settings with units.
4 ALTER STABLE Adjusted Deprecated
  • CHANGE tag: Change the name of the tag column. Replaced by RENAME tag in version 3.0.
    Added
  • RENAME tag: Replaces the original CHANGE tag clause.
  • COMMENT: Modify the comment of the supertable.
5 ALTER TABLE Adjusted Deprecated
  • CHANGE tag: Change the name of the tag column. Replaced by RENAME tag in version 3.0.
    Added
  • RENAME tag: Replaces the original CHANGE tag clause.
  • COMMENT: Modify the comment of the table.
  • TTL: Modify the lifecycle of the table.
6 ALTER USER Adjusted Deprecated
  • PRIVILEGE: Modify user permissions. Version 3.0 uses GRANT and REVOKE to grant and revoke permissions.
    Added
  • ENABLE: Enable or disable this user.
  • SYSINFO: Modify whether the user can view system information.
7 COMPACT VNODES Not supported Compact data of specified VNODE. Not supported in version 3.0.0.
8 CREATE ACCOUNT Deprecated Was an enterprise feature in 2.x, no longer supported in 3.0. Syntax is temporarily retained, execution reports “This statement is no longer supported” error.
9 CREATE DATABASE Adjusted

Deprecated

  • BLOCKS: The number of memory blocks used by VNODE. Version 3.0 uses BUFFER to represent the size of the VNODE write memory pool.
  • CACHE: The size of memory blocks used by VNODE. Version 3.0 uses BUFFER to represent the size of the VNODE write memory pool.
  • CACHELAST: Mode for caching the latest row of data. Replaced by CACHEMODEL in version 3.0.
  • DAYS: The time span for storing data in data files. Replaced by DURATION in version 3.0.
  • FSYNC: When WAL is set to 2, the period for performing fsync. Replaced by WAL_FSYNC_PERIOD in version 3.0.
  • QUORUM: The number of replica confirmations needed for writing. Version 3.0 uses STRICT to specify strong or weak consistency.
  • UPDATE: Support mode for update operations. All databases in version 3.0 support partial column updates.
  • WAL: WAL level. Replaced by WAL_LEVEL in version 3.0.

Added

  • BUFFER: The size of the memory pool for a VNODE write.
  • CACHEMODEL: Indicates whether to cache recent data of subtables in memory.
  • CACHESIZE: Indicates the memory size for caching recent data of subtables.
  • DURATION: Replaces the original DAYS parameter. Added support for settings with units.
  • PAGES: The number of cache pages in the metadata storage engine of a VNODE.
  • PAGESIZE: The page size in the metadata storage engine of a VNODE.
  • RETENTIONS: Indicates the data aggregation period and retention duration.
  • STRICT: Indicates the consistency requirement for data synchronization.
  • SINGLE_STABLE: Indicates whether only one supertable can be created in this database.
  • VGROUPS: The initial number of VGROUPs in the database.
  • WAL_FSYNC_PERIOD: Replaces the original FSYNC parameter.
  • WAL_LEVEL: Replaces the original WAL parameter.
  • WAL_RETENTION_PERIOD: Extra retention strategy for wal files, used for data subscription.
  • WAL_RETENTION_SIZE: Extra retention strategy for wal files, used for data subscription.

Adjusted

  • KEEP: Version 3.0 added support for settings with units.
10 CREATE DNODE Adjusted Added syntax to specify hostname and port number separately
  • CREATE DNODE dnode_host_name PORT port_val
11 CREATE INDEX Added Create SMA index.
12 CREATE MNODE Added Create management node.
13 CREATE QNODE Added Create query node.
14 CREATE STABLE Adjusted Added table parameter syntax
  • COMMENT: Table comment.
    		•
    15 CREATE STREAM Added Create stream.
    16 CREATE TABLE Adjusted Added table parameter syntax
    • COMMENT: Table comment.
    • WATERMARK: Specifies the closing time of the window.
    • MAX_DELAY: Used to control the maximum delay in pushing calculation results.
    • ROLLUP: Specifies the aggregation function, providing multi-level downsampling aggregation results.
    • SMA: Provides custom pre-computation based on data blocks.
    • TTL: Parameter used to specify the lifecycle of the table.
    17 CREATE TOPIC Added Create subscription topic.
    18 DROP ACCOUNT Deprecated Was an enterprise feature in 2.x, no longer supported in 3.0. Syntax is temporarily retained, execution reports “This statement is no longer supported” error.
    19 DROP CONSUMER GROUP Added Delete consumer group.
    20 DROP INDEX Added Delete index.
    21 DROP MNODE Added Create management node.
    22 DROP QNODE Added Create query node.
    23 DROP STREAM Added Delete stream.
    24 DROP TABLE Adjusted Added batch delete syntax
    25 DROP TOPIC Added Delete subscription topic.
    26 EXPLAIN Added View the execution plan of a query statement.
    27 GRANT Added Grant user permissions.
    28 KILL TRANSACTION Added Terminate the transaction of the management node.
    29 KILL STREAM Deprecated Terminate continuous query. Version 3.0 no longer supports continuous queries, replaced by more general stream computing.
    31 REVOKE Added Revoke user permissions.
    32 SELECT Adjusted
    • SELECT closes implicit result columns, output columns must be specified by the SELECT clause.
    • DISTINCT functionality fully supported. Version 2.x only supported deduplication of tag columns and could not be mixed with JOIN, GROUP BY, etc.
    • JOIN functionality enhanced. Added support: OR conditions in WHERE conditions after JOIN; multi-table operations after JOIN; multi-table GROUP BY after JOIN.
    • Subquery functionality after FROM significantly enhanced. No limit on subquery nesting levels; supports mixed use of subqueries and UNION ALL; removes some other previous version syntax restrictions.
    • Any scalar expression can be used after WHERE.
    • GROUP BY functionality enhanced. Supports any scalar expression and their combinations for grouping.
    • SESSION can be used for supertables now. Without PARTITION BY, the data of the supertable will be merged into one timeline.
    • STATE_WINDOW can be used for supertables now. Without PARTITION BY, the data of the supertable will be merged into one timeline.
    • ORDER BY functionality significantly enhanced. No longer must be used with the GROUP BY clause; no longer has a limit on the number of sorting expressions; added support for NULLS FIRST/LAST syntax functionality; supports any expression complying with syntax semantics.
    • Added PARTITION BY syntax. Replaces the original GROUP BY tags.
    33 SHOW ACCOUNTS Deprecated Was an enterprise feature in 2.x, no longer supported in 3.0. Syntax is temporarily retained, execution reports “This statement is no longer supported” error.
    34 SHOW APPS Added Display information about applications (clients) accessing the cluster.
    35 SHOW CONSUMERS Added Display information about all active consumers in the current database.
    36 SHOW DATABASES Adjusted Version 3.0 only displays database names.
    37 SHOW FUNCTIONS Adjusted Version 3.0 only displays custom function names.
    38 SHOW LICENCE Added Equivalent to the SHOW GRANTS command.
    39 SHOW INDEXES Added Display created indexes.
    40 SHOW LOCAL VARIABLES Added Display runtime values of the current client's configuration parameters.
    41 SHOW MODULES Deprecated Display information about components installed in the current system.
    42 SHOW QNODES Added Display information about QNODEs in the current system.
    43 SHOW STABLES Adjusted Version 3.0 only displays supertable names.
    44 SHOW STREAMS Adjusted Version 2.x this command displayed information about continuous queries created in the system. Version 3.0 has deprecated continuous queries, replaced by streams. This command displays created streams.
    45 SHOW SUBSCRIPTIONS Added Display all subscription relationships in the current database
    46 SHOW TABLES Adjusted Version 3.0 only displays table names.
    47 SHOW TABLE DISTRIBUTED Added Display table data distribution information. Replaces the SELECT _block_dist() FROM { tb_name
    48 SHOW TOPICS Added Display all subscription topics in the current database.
    49 SHOW TRANSACTIONS Added Display information about transactions currently being executed in the system.
    50 SHOW DNODE VARIABLES Added Display configuration parameters of a specified DNODE.
    51 SHOW VNODES Not supported Display information about VNODEs in the current system. Not supported in version 3.0.0.
    52 TRIM DATABASE Added Delete expired data and reorganize data according to multi-level storage configuration.
    53 REDISTRIBUTE VGROUP Added Adjust the distribution of VNODEs in a VGROUP.
    54 BALANCE VGROUP Added Automatically adjust the distribution of VNODEs in a VGROUP.

    SQL Function Changes

    # Function <div style={{width: 60}}>Differences Description
    1 TWA Enhanced Can now be used directly on supertables. Without PARTITION BY, the data of the supertable will be merged into one timeline.
    2 IRATE Enhanced Can now be used directly on supertables. Without PARTITION BY, the data of the supertable will be merged into one timeline.
    3 LEASTSQUARES Enhanced Can now be used on supertables.
    4 ELAPSED Enhanced Can now be used directly on supertables. Without PARTITION BY, the data of the supertable will be merged into one timeline.
    5 DIFF Enhanced Can now be used directly on supertables. Without PARTITION BY, the data of the supertable will be merged into one timeline.
    6 DERIVATIVE Enhanced Can now be used directly on supertables. Without PARTITION BY, the data of the supertable will be merged into one timeline.
    7 CSUM Enhanced Can now be used directly on supertables. Without PARTITION BY, the data of the supertable will be merged into one timeline.
    8 MAVG Enhanced Can now be used directly on supertables. Without PARTITION BY, the data of the supertable will be merged into one timeline.
    9 SAMPLE Enhanced Can now be used directly on supertables. Without PARTITION BY, the data of the supertable will be merged into one timeline.
    10 STATECOUNT Enhanced Can now be used directly on supertables. Without PARTITION BY, the data of the supertable will be merged into one timeline.
    11 STATEDURATION Enhanced Can now be used directly on supertables. Without PARTITION BY, the data of the supertable will be merged into one timeline.
    12 TIMETRUNCATE Enhanced Added ignore_timezone parameter, optional use, default value is 1.

    SCHEMALESS Changes

    # Element <div style={{width: 60}}>Differences Description
    1 Primary key ts changed to _ts Changed Schemaless automatically created column names start with _, different from 2.x.