104 lines
20 KiB
Markdown
104 lines
20 KiB
Markdown
---
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title: Syntax Changes in TDengine 3.0
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slug: /tdengine-reference/sql-manual/syntax-changes
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---
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## Changes to SQL Basic Elements
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| # | **Element** | **<div style={{width: 60}}>Difference</div>** | **Description** |
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| ---- | :-------------------------------------------------------- | :-------------------------------------------- | :----------------------------------------------------------- |
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| 1 | VARCHAR | Added | Alias for the BINARY type. |
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| 2 | TIMESTAMP literal | Added | Supports the syntax TIMESTAMP 'timestamp format'. |
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| 3 | _ROWTS pseudocolumn | Added | Represents the timestamp primary key. Alias for the _C0 pseudo column. |
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| 4 | _IROWTS pseudocolumn | Added | Used to return the timestamp column corresponding to the interpolation result of the interp function. |
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| 5 | INFORMATION_SCHEMA | Added | System database containing various SCHEMA definitions. |
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| 6 | PERFORMANCE_SCHEMA | Added | System database containing operational information. |
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| 7 | Continuous Query | Deprecated | Continuous queries are no longer supported. Various related syntax and interfaces are deprecated. |
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| 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. |
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| 9 | Tag Operations | Added | In queries, tag columns can participate in various operations like normal columns, used in various clauses. |
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| 10 | Timeline Clause and Time Functions for Supertable Queries | Enhanced | Without PARTITION BY, the data of the supertable will be merged into one timeline. |
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| 11 | GEOMETRY | Added | Geometry type. |
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## SQL Statement Changes
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In TDengine, the following data types can be used in the data model of basic tables.
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| # | **Statement** | **<div style={{width: 60}}>Difference</div>** | **Description** |
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| ---- | :--------------------- | :-------------------------------------------- | :----------------------------------------------------------- |
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| 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. |
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| 2 | ALTER ALL DNODES | Added | Modify parameters of all DNODEs. |
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| 3 | ALTER DATABASE | Adjusted | <p>Deprecated</p><ul><li>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.</li><li>BLOCKS: The number of memory blocks used by VNODE. Version 3.0 uses BUFFER to represent the size of the VNODE write memory pool.</li><li>UPDATE: Support mode for update operations. All databases in version 3.0 support partial column updates.</li><li>CACHELAST: Mode for caching the latest row of data. Replaced by CACHEMODEL in version 3.0.</li><li>COMP: Not supported for modification in version 3.0.</li></ul><p>Added</p><ul><li>CACHEMODEL: Indicates whether to cache recent data of subtables in memory.</li><li>CACHESIZE: Indicates the memory size for caching recent data of subtables.</li><li>WAL_FSYNC_PERIOD: Replaces the original FSYNC parameter.</li><li>WAL_LEVEL: Replaces the original WAL parameter.</li><li>WAL_RETENTION_PERIOD: Added in version 3.0.4.0, extra retention strategy for wal files, used for data subscription.</li><li>WAL_RETENTION_SIZE: Added in version 3.0.4.0, extra retention strategy for wal files, used for data subscription.</li></ul><p>Adjusted</p><ul><li>KEEP: Version 3.0 added support for settings with units.</li></ul> |
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| 4 | ALTER STABLE | Adjusted | Deprecated<ul><li>CHANGE tag: Change the name of the tag column. Replaced by RENAME tag in version 3.0.<br/>Added</li><li>RENAME tag: Replaces the original CHANGE tag clause.</li><li>COMMENT: Modify the comment of the supertable.</li></ul> |
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| 5 | ALTER TABLE | Adjusted | Deprecated<ul><li>CHANGE tag: Change the name of the tag column. Replaced by RENAME tag in version 3.0.<br/>Added</li><li>RENAME tag: Replaces the original CHANGE tag clause.</li><li>COMMENT: Modify the comment of the table.</li><li>TTL: Modify the lifecycle of the table.</li></ul> |
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| 6 | ALTER USER | Adjusted | Deprecated<ul><li>PRIVILEGE: Modify user permissions. Version 3.0 uses GRANT and REVOKE to grant and revoke permissions.<br/>Added</li><li>ENABLE: Enable or disable this user.</li><li>SYSINFO: Modify whether the user can view system information.</li></ul> |
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| 7 | COMPACT VNODES | Not supported | Compact data of specified VNODE. Not supported in version 3.0.0. |
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| 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. |
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| 9 | CREATE DATABASE | Adjusted | <p>Deprecated</p><ul><li>BLOCKS: The number of memory blocks used by VNODE. Version 3.0 uses BUFFER to represent the size of the VNODE write memory pool.</li><li>CACHE: The size of memory blocks used by VNODE. Version 3.0 uses BUFFER to represent the size of the VNODE write memory pool.</li><li>CACHELAST: Mode for caching the latest row of data. Replaced by CACHEMODEL in version 3.0.</li><li>DAYS: The time span for storing data in data files. Replaced by DURATION in version 3.0.</li><li>FSYNC: When WAL is set to 2, the period for performing fsync. Replaced by WAL_FSYNC_PERIOD in version 3.0.</li><li>QUORUM: The number of replica confirmations needed for writing. Version 3.0 uses STRICT to specify strong or weak consistency.</li><li>UPDATE: Support mode for update operations. All databases in version 3.0 support partial column updates.</li><li>WAL: WAL level. Replaced by WAL_LEVEL in version 3.0.</li></ul><p>Added</p><ul><li>BUFFER: The size of the memory pool for a VNODE write.</li><li>CACHEMODEL: Indicates whether to cache recent data of subtables in memory.</li><li>CACHESIZE: Indicates the memory size for caching recent data of subtables.</li><li>DURATION: Replaces the original DAYS parameter. Added support for settings with units.</li><li>PAGES: The number of cache pages in the metadata storage engine of a VNODE.</li><li>PAGESIZE: The page size in the metadata storage engine of a VNODE.</li><li>RETENTIONS: Indicates the data aggregation period and retention duration.</li><li>STRICT: Indicates the consistency requirement for data synchronization.</li><li>SINGLE_STABLE: Indicates whether only one supertable can be created in this database.</li><li>VGROUPS: The initial number of VGROUPs in the database.</li><li>WAL_FSYNC_PERIOD: Replaces the original FSYNC parameter.</li><li>WAL_LEVEL: Replaces the original WAL parameter.</li><li>WAL_RETENTION_PERIOD: Extra retention strategy for wal files, used for data subscription.</li><li>WAL_RETENTION_SIZE: Extra retention strategy for wal files, used for data subscription.</li></ul><p>Adjusted</p><ul><li>KEEP: Version 3.0 added support for settings with units.</li></ul> |
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| 10 | CREATE DNODE | Adjusted | Added syntax to specify hostname and port number separately<ul><li>CREATE DNODE dnode_host_name PORT port_val</li></ul> |
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| 11 | CREATE INDEX | Added | Create SMA index. |
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| 12 | CREATE MNODE | Added | Create management node. |
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| 13 | CREATE QNODE | Added | Create query node. |
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| 14 | CREATE STABLE | Adjusted | Added table parameter syntax<li>COMMENT: Table comment.</li> |
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| 15 | CREATE STREAM | Added | Create stream. |
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| 16 | CREATE TABLE | Adjusted | Added table parameter syntax<ul><li>COMMENT: Table comment.</li><li>WATERMARK: Specifies the closing time of the window.</li><li>MAX_DELAY: Used to control the maximum delay in pushing calculation results.</li><li>ROLLUP: Specifies the aggregation function, providing multi-level downsampling aggregation results.</li><li>SMA: Provides custom pre-computation based on data blocks.</li><li>TTL: Parameter used to specify the lifecycle of the table.</li></ul> |
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| 17 | CREATE TOPIC | Added | Create subscription topic. |
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| 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. |
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| 19 | DROP CONSUMER GROUP | Added | Delete consumer group. |
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| 20 | DROP INDEX | Added | Delete index. |
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| 21 | DROP MNODE | Added | Create management node. |
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| 22 | DROP QNODE | Added | Create query node. |
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| 23 | DROP STREAM | Added | Delete stream. |
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| 24 | DROP TABLE | Adjusted | Added batch delete syntax |
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| 25 | DROP TOPIC | Added | Delete subscription topic. |
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| 26 | EXPLAIN | Added | View the execution plan of a query statement. |
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| 27 | GRANT | Added | Grant user permissions. |
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| 28 | KILL TRANSACTION | Added | Terminate the transaction of the management node. |
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| 29 | KILL STREAM | Deprecated | Terminate continuous query. Version 3.0 no longer supports continuous queries, replaced by more general stream computing. |
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| 31 | REVOKE | Added | Revoke user permissions. |
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| 32 | SELECT | Adjusted | <ul><li>SELECT closes implicit result columns, output columns must be specified by the SELECT clause.</li><li>DISTINCT functionality fully supported. Version 2.x only supported deduplication of tag columns and could not be mixed with JOIN, GROUP BY, etc.</li><li>JOIN functionality enhanced. Added support: OR conditions in WHERE conditions after JOIN; multi-table operations after JOIN; multi-table GROUP BY after JOIN.</li><li>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.</li><li>Any scalar expression can be used after WHERE.</li><li>GROUP BY functionality enhanced. Supports any scalar expression and their combinations for grouping.</li><li>SESSION can be used for supertables now. Without PARTITION BY, the data of the supertable will be merged into one timeline.</li><li>STATE_WINDOW can be used for supertables now. Without PARTITION BY, the data of the supertable will be merged into one timeline.</li><li>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.</li><li>Added PARTITION BY syntax. Replaces the original GROUP BY tags.</li></ul> |
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| 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. |
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| 34 | SHOW APPS | Added | Display information about applications (clients) accessing the cluster. |
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| 35 | SHOW CONSUMERS | Added | Display information about all active consumers in the current database. |
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| 36 | SHOW DATABASES | Adjusted | Version 3.0 only displays database names. |
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| 37 | SHOW FUNCTIONS | Adjusted | Version 3.0 only displays custom function names. |
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| 38 | SHOW LICENCE | Added | Equivalent to the SHOW GRANTS command. |
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| 39 | SHOW INDEXES | Added | Display created indexes. |
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| 40 | SHOW LOCAL VARIABLES | Added | Display runtime values of the current client's configuration parameters. |
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| 41 | SHOW MODULES | Deprecated | Display information about components installed in the current system. |
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| 42 | SHOW QNODES | Added | Display information about QNODEs in the current system. |
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| 43 | SHOW STABLES | Adjusted | Version 3.0 only displays supertable names. |
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| 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. |
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| 45 | SHOW SUBSCRIPTIONS | Added | Display all subscription relationships in the current database |
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| 46 | SHOW TABLES | Adjusted | Version 3.0 only displays table names. |
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| 47 | SHOW TABLE DISTRIBUTED | Added | Display table data distribution information. Replaces the SELECT _block_dist() FROM \{ tb_name |
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| 48 | SHOW TOPICS | Added | Display all subscription topics in the current database. |
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| 49 | SHOW TRANSACTIONS | Added | Display information about transactions currently being executed in the system. |
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| 50 | SHOW DNODE VARIABLES | Added | Display configuration parameters of a specified DNODE. |
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| 51 | SHOW VNODES | Not supported | Display information about VNODEs in the current system. Not supported in version 3.0.0. |
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| 52 | TRIM DATABASE | Added | Delete expired data and reorganize data according to multi-level storage configuration. |
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| 53 | REDISTRIBUTE VGROUP | Added | Adjust the distribution of VNODEs in a VGROUP. |
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| 54 | BALANCE VGROUP | Added | Automatically adjust the distribution of VNODEs in a VGROUP. |
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## SQL Function Changes
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| # | **Function** | **<div style={{width: 60}}>Differences</div>** | **Description** |
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| ---- | :------------ | :--------------------------------------------- | :----------------------------------------------------------- |
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| 1 | TWA | Enhanced | Can now be used directly on supertables. Without PARTITION BY, the data of the supertable will be merged into one timeline. |
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| 2 | IRATE | Enhanced | Can now be used directly on supertables. Without PARTITION BY, the data of the supertable will be merged into one timeline. |
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| 3 | LEASTSQUARES | Enhanced | Can now be used on supertables. |
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| 4 | ELAPSED | Enhanced | Can now be used directly on supertables. Without PARTITION BY, the data of the supertable will be merged into one timeline. |
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| 5 | DIFF | Enhanced | Can now be used directly on supertables. Without PARTITION BY, the data of the supertable will be merged into one timeline. |
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| 6 | DERIVATIVE | Enhanced | Can now be used directly on supertables. Without PARTITION BY, the data of the supertable will be merged into one timeline. |
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| 7 | CSUM | Enhanced | Can now be used directly on supertables. Without PARTITION BY, the data of the supertable will be merged into one timeline. |
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| 8 | MAVG | Enhanced | Can now be used directly on supertables. Without PARTITION BY, the data of the supertable will be merged into one timeline. |
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| 9 | SAMPLE | Enhanced | Can now be used directly on supertables. Without PARTITION BY, the data of the supertable will be merged into one timeline. |
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| 10 | STATECOUNT | Enhanced | Can now be used directly on supertables. Without PARTITION BY, the data of the supertable will be merged into one timeline. |
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| 11 | STATEDURATION | Enhanced | Can now be used directly on supertables. Without PARTITION BY, the data of the supertable will be merged into one timeline. |
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| 12 | TIMETRUNCATE | Enhanced | Added ignore_timezone parameter, optional use, default value is 1. |
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## SCHEMALESS Changes
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| # | **Element** | **<div style={{width: 60}}>Differences</div>** | **Description** |
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| ---- | :---------------------------- | :--------------------------------------------- | :----------------------------------------------------------- |
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| 1 | Primary key ts changed to _ts | Changed | Schemaless automatically created column names start with _, different from 2.x. |
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