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Syntax Changes in TDengine 3.0 Syntax change notes for TDengine version 3.0 /tdengine-reference/sql-manual/syntax-changes-in-tdengine-3

Changes to SQL Basic Elements

# Element Difference Description
1 VARCHAR New Alias for BINARY type.
2 TIMESTAMP Literal New Supports TIMESTAMP 'timestamp format' syntax.
3 _ROWTS Pseudo Column New Represents the timestamp primary key. Alias for _C0 pseudo column.
4 _IROWTS Pseudo Column New Used to return the timestamp column corresponding to the interp function interpolation result.
5 INFORMATION_SCHEMA New System database containing various SCHEMA definitions.
6 PERFORMANCE_SCHEMA New System database containing runtime information.
7 Continuous Query Deprecated Continuous queries are no longer supported. Related syntax and interfaces are deprecated.
8 Mixed Operations Enhanced Mixed operations (scalar and vector operations) in queries are fully enhanced, with all subclauses of SELECT fully supporting syntax semantics of mixed operations.
9 Tag Operations New In queries, tag columns can participate in various operations like ordinary columns for various clauses.
10 Timeline Clause and Time Functions for Supertable Queries Enhanced Without PARTITION BY, the data of supertables will be merged into one timeline.
11 GEOMETRY New Geometry type.

Changes to SQL Statements

In TDengine, the data model of basic tables can use the following data types.

# Statement Difference Description
1 ALTER ACCOUNT Deprecated This was a feature in the enterprise version of 2.x, not supported in 3.0. The syntax is temporarily retained, executing results in "This statement is no longer supported" error.
2 ALTER ALL DNODES New Modify parameters for all DNODEs.
3 ALTER DATABASE Adjusted

Deprecated

  • QUORUM: The number of replicas required for write confirmation. The default behavior in version 3.0 is strong consistency and does not support modification to weak consistency.
  • 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. Version 3.0 supports partial column updates for all databases.
  • CACHELAST: Mode for caching the latest row of data. Version 3.0 replaces it with CACHEMODEL.
  • COMP: Not supported for modification in version 3.0.

New

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

Adjusted

  • KEEP: Version 3.0 adds support for setting with units.
4 ALTER STABLE Adjusted Deprecated
  • CHANGE TAG: Modify the name of a tag column. Version 3.0 uses RENAME TAG instead.
    New
  • RENAME TAG: Replaces the original CHANGE TAG clause.
  • COMMENT: Modifies the comment of the supertable.
5 ALTER TABLE Adjusted Deprecated
  • CHANGE TAG: Modify the name of a tag column. Version 3.0 uses RENAME TAG instead.
    New
  • RENAME TAG: Replaces the original CHANGE TAG clause.
  • COMMENT: Modifies the table's comment.
  • TTL: Modifies the table's lifecycle.
6 ALTER USER Adjusted Deprecated
  • PRIVILEGE: Modify user permissions. Version 3.0 uses GRANT and REVOKE to grant and revoke permissions.
    New
  • ENABLE: Enable or disable this user.
  • SYSINFO: Modify whether the user can view system information.
7 COMPACT VNODES Not Supported Organize the data of the specified VNODE. Not supported in version 3.0.0.
8 CREATE ACCOUNT Deprecated This was a feature in the enterprise version of 2.x, not supported in 3.0. The syntax is temporarily retained, executing results in "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 the 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. Version 3.0 replaces it with CACHEMODEL.
  • DAYS: The time span for data file storage. Version 3.0 replaces it with DURATION.
  • FSYNC: The period of executing fsync when WAL is set to 2. Version 3.0 replaces it with WAL_FSYNC_PERIOD.
  • QUORUM: The number of replicas required for write confirmation. Version 3.0 uses STRICT to specify strong or weak consistency.
  • UPDATE: Support mode for update operations. Version 3.0 supports partial column updates for all databases.
  • WAL: WAL level. Version 3.0 replaces it with WAL_LEVEL.

New

  • BUFFER: The size of a VNODE's write memory pool.
  • CACHEMODEL: Indicates whether to cache the most recent data of subtables in memory.
  • CACHESIZE: Indicates the memory size used to cache the most recent data of subtables.
  • DURATION: Replaces the original DAYS parameter. Adds support for setting with units.
  • PAGES: The number of cached pages in a VNODE's metadata storage engine.
  • PAGESIZE: The page size of the metadata storage engine in a VNODE.
  • RETENTIONS: Indicates the aggregation cycle and retention duration of the data.
  • STRICT: Indicates the consistency requirements 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: Additional retention strategy for wal files, used for data subscription.
  • WAL_RETENTION_SIZE: Additional retention strategy for wal files, used for data subscription.

Adjusted

  • KEEP: Version 3.0 adds support for setting with units.
10 CREATE DNODE Adjusted New syntax for specifying hostname and port separately
  • CREATE DNODE dnode_host_name PORT port_val
11 CREATE INDEX New Create SMA index.
12 CREATE MNODE New Create management node.
13 CREATE QNODE New Create query node.
14 CREATE STABLE Adjusted New table parameter syntax
  • COMMENT: Table comment.
    		•
    15 CREATE STREAM New Create stream.
    16 CREATE TABLE Adjusted New table parameter syntax
    • COMMENT: Table comment.
    • WATERMARK: Specify the closing time of the window.
    • MAX_DELAY: Control the maximum delay for pushing computation results.
    • ROLLUP: Specify aggregation functions, providing down-sampling aggregation results based on multiple levels.
    • SMA: Provide custom pre-calculation functions based on data blocks.
    • TTL: Parameter used to specify the lifecycle of the table.
    17 CREATE TOPIC New Create subscription topic.
    18 DROP ACCOUNT Deprecated This was a feature in the enterprise version of 2.x, not supported in 3.0. The syntax is temporarily retained, executing results in "This statement is no longer supported" error.
    19 DROP CONSUMER GROUP New Delete consumer group.
    20 DROP INDEX New Delete index.
    21 DROP MNODE New Create management node.
    22 DROP QNODE New Create query node.
    23 DROP STREAM New Delete stream.
    24 DROP TABLE Adjusted New syntax for batch deletion.
    25 DROP TOPIC New Delete subscription topic.
    26 EXPLAIN New View the execution plan of a query statement.
    27 GRANT New Grant user permissions.
    28 KILL TRANSACTION New Terminate the transaction management node.
    29 KILL STREAM Deprecated Terminate continuous queries. Continuous queries are no longer supported in version 3.0 and are replaced by a more generic stream computation.
    31 REVOKE New Revoke user permissions.
    32 SELECT Adjusted
    • SELECT closes implicit result columns; all output columns must be specified in the SELECT clause.
    • DISTINCT functionality is fully supported. Version 2.x only supported deduplication of tag columns and could not be mixed with JOIN, GROUP BY, etc.
    • JOIN functionality is enhanced. Added support for: WHERE conditions with OR after JOIN; multi-table operations after JOIN; multi-table GROUP BY after JOIN.
    • Subquery functionality after FROM is significantly enhanced. No restriction on the number of nested subqueries; supports mixing subqueries with UNION ALL; removes some syntax restrictions from previous versions.
    • Arbitrary scalar expressions can be used after WHERE.
    • GROUP BY functionality is enhanced. Supports grouping by any scalar expression and their combinations.
    • SESSION can now be used for supertables. Without PARTITION BY, the data of supertables will be merged into one timeline.
    • STATE_WINDOW can now be used for supertables. Without PARTITION BY, the data of supertables will be merged into one timeline.
    • ORDER BY functionality is greatly enhanced. No longer must be used together with the GROUP BY clause; no longer has a limit on the number of sorting expressions; adds support for NULLS FIRST/LAST syntax; supports any expression that meets the syntax semantics.
    • New PARTITION BY syntax replaces the original GROUP BY tags.
    33 SHOW ACCOUNTS Deprecated This was a feature in the enterprise version of 2.x, not supported in 3.0. The syntax is temporarily retained, executing results in "This statement is no longer supported" error.
    34 SHOW APPS New Displays information about applications (clients) accessing the cluster.
    35 SHOW CONSUMERS New Displays 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 New Equivalent to the SHOW GRANTS command.
    39 SHOW INDEXES New Displays the indexes that have been created.
    40 SHOW LOCAL VARIABLES New Displays the runtime values of the current client configuration parameters.
    41 SHOW MODULES Deprecated Displays information about the components installed in the current system.
    42 SHOW QNODES New Displays information about QNODEs in the current system.
    43 SHOW STABLES Adjusted Version 3.0 only displays supertable names.
    44 SHOW STREAMS Adjusted In version 2.x, this command displayed information about the continuous queries created in the system. Continuous queries are deprecated in version 3.0, replaced by streams. This command displays the streams that have been created.
    45 SHOW SUBSCRIPTIONS New Displays all subscription relationships in the current database.
    46 SHOW TABLES Adjusted Version 3.0 only displays table names.
    47 SHOW TABLE DISTRIBUTED New Displays the data distribution information of a table. Replaces the SELECT _block_dist() FROM { tb_name
    48 SHOW TOPICS New Displays all subscription topics in the current database.
    49 SHOW TRANSACTIONS New Displays information about transactions currently being executed in the system.
    50 SHOW DNODE VARIABLES New Displays configuration parameters for the specified DNODE.
    51 SHOW VNODES Not Supported Displays information about VNODES in the current system. Not supported in version 3.0.0.
    52 TRIM DATABASE New Deletes expired data and organizes data based on multi-level storage configuration.
    53 REDISTRIBUTE VGROUP New Adjusts the distribution of VNODES in VGROUP.
    54 BALANCE VGROUP New Automatically adjusts the distribution of VNODES in VGROUP.

    Changes to SQL Functions

    # Function Difference Description
    1 TWA Enhanced Can now be used directly with supertables. Without PARTITION BY, the data of supertables will be merged into one timeline.
    2 IRATE Enhanced Can now be used directly with supertables. Without PARTITION BY, the data of supertables will be merged into one timeline.
    3 LEASTSQUARES Enhanced Can be used with supertables.
    4 ELAPSED Enhanced Can now be used directly with supertables. Without PARTITION BY, the data of supertables will be merged into one timeline.
    5 DIFF Enhanced Can now be used directly with supertables. Without PARTITION BY, the data of supertables will be merged into one timeline.
    6 DERIVATIVE Enhanced Can now be used directly with supertables. Without PARTITION BY, the data of supertables will be merged into one timeline.
    7 CSUM Enhanced Can now be used directly with supertables. Without PARTITION BY, the data of supertables will be merged into one timeline.
    8 MAVG Enhanced Can now be used directly with supertables. Without PARTITION BY, the data of supertables will be merged into one timeline.
    9 SAMPLE Enhanced Can now be used directly with supertables. Without PARTITION BY, the data of supertables will be merged into one timeline.
    10 STATECOUNT Enhanced Can now be used directly with supertables. Without PARTITION BY, the data of supertables will be merged into one timeline.
    11 STATEDURATION Enhanced Can now be used directly with supertables. Without PARTITION BY, the data of supertables will be merged into one timeline.
    12 TIMETRUNCATE Enhanced Adds ignore_timezone parameter, which is optional and defaults to 1.

    Changes to SCHEMALESS

    # Element Difference Description
    1 Primary Key ts changed to _ts Change Automatically created column names in schemaless begin with an underscore, unlike 2.x.