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docs:[TD-30027]modify subtable rules in stream document

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wangmm0220 2024-06-03 19:23:55 +08:00
parent 0c8e9046f6
commit ca15176f75
2 changed files with 2 additions and 2 deletions
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2
docs/en/12-taos-sql/14-stream.md
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@ -80,7 +80,7 @@ If a stream is created with PARTITION BY clause and SUBTABLE clause, the name of
CREATE STREAM avg_vol_s INTO avg_vol SUBTABLE(CONCAT('new-', tname)) AS SELECT _wstart, count(*), avg(voltage) FROM meters PARTITION BY tbname tname INTERVAL(1m);
```
IN PARTITION clause, 'tbname', representing each subtable name of source supertable, is given alias 'tname'. And 'tname' is used in SUBTABLE clause. In SUBTABLE clause, each auto created subtable will concat 'new-' and source subtable name as their name(Starting from 3.2.3.0, in order to avoid the expression in subtable being unable to distinguish between different subtables, add '_groupId' to the end of subtable name).
IN PARTITION clause, 'tbname', representing each subtable name of source supertable, is given alias 'tname'. And 'tname' is used in SUBTABLE clause. In SUBTABLE clause, each auto created subtable will concat 'new-' and source subtable name as their name(Starting from 3.2.3.0, in order to avoid the expression in subtable being unable to distinguish between different subtables, add '_stableName_groupId' to the end of subtable name).
If the output length exceeds the limitation of TDengine(192), the name will be truncated. If the generated name is occupied by some other table, the creation and writing of the new subtable will be failed.

2
docs/zh/12-taos-sql/14-stream.md
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@ -91,7 +91,7 @@ SELECT _wstart, count(*), avg(voltage) from meters PARTITION BY tbname COUNT_WIN
CREATE STREAM avg_vol_s INTO avg_vol SUBTABLE(CONCAT('new-', tname)) AS SELECT _wstart, count(*), avg(voltage) FROM meters PARTITION BY tbname tname INTERVAL(1m);
```
PARTITION 子句中，为 tbname 定义了一个别名 tname, 在PARTITION 子句中的别名可以用于 SUBTABLE 子句中的表达式计算，在上述示例中，流新创建的子表将以前缀 'new-' 连接原表名作为表名(从3.2.3.0开始，为了避免 sutable 中的表达式无法区分各个子表，即误将多个相同时间线写入一个子表，在指定的子表名后面加上 _groupId)。
PARTITION 子句中，为 tbname 定义了一个别名 tname, 在PARTITION 子句中的别名可以用于 SUBTABLE 子句中的表达式计算，在上述示例中，流新创建的子表将以前缀 'new-' 连接原表名作为表名(从3.2.3.0开始，为了避免 sutable 中的表达式无法区分各个子表，即误将多个相同时间线写入一个子表，在指定的子表名后面加上 __stableName_groupId)。
注意，子表名的长度若超过 TDengine 的限制，将被截断。若要生成的子表名已经存在于另一超级表，由于 TDengine 的子表名是唯一的，因此对应新子表的创建以及数据的写入将会失败。