docs: interp ins
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@ -278,7 +278,7 @@ TDengine supports INNER JOIN based on the timestamp primary key, with the follow
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6. Does not support mixing with the FILL clause.
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## INTERP
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The INTERP clause is used in conjunction with the [INTERP](../function/#interp) function to determine the rules for capturing time slices and interpolation when the INTERP function is executed.
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The INTERP clause is a dedicated syntax for the INTERP function (../function/#interp). When an SQL statement contains an INTERP clause, it can only query the INTERP function and cannot be used with other functions. Additionally, the INTERP clause cannot be used simultaneously with window clauses (window_clause) or group by clauses (group_by_clause). The INTERP function must be used with the RANGE, EVERY, and FILL clauses; stream computing does not support the use of RANGE but requires the use of the EVERY and FILL keywords.
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- The output time range for INTERP is specified by the RANGE(timestamp1, timestamp2) field, which must satisfy timestamp1 \<= timestamp2. Here, timestamp1 is the start value of the output time range, i.e., if the conditions for interpolation are met at timestamp1, then timestamp1 is the first record output, and timestamp2 is the end value of the output time range, i.e., the timestamp of the last record output cannot be greater than timestamp2.
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- INTERP determines the number of results within the output time range based on the EVERY(time_unit) field, starting from timestamp1 and interpolating at fixed intervals of time (time_unit value), where time_unit can be time units: 1a (milliseconds), 1s (seconds), 1m (minutes), 1h (hours), 1d (days), 1w (weeks). For example, EVERY(500a) will interpolate the specified data every 500 milliseconds.
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- INTERP determines how to interpolate at each time point that meets the output conditions based on the FILL field. For how to use the FILL clause, refer to [FILL Clause](../time-series-extensions/)
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@ -2196,16 +2196,14 @@ ignore_null_values: {
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**Usage Instructions**
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- INTERP is used to obtain the record value of a specified column at a specified time slice. If there is no row data that meets the conditions at that time slice, interpolation will be performed according to the settings of the [FILL](../distinguished/#FILL-Clause) parameter.
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- INTERP is used to obtain the record value of a specified column at the specified time slice. It has a dedicated syntax (interp_clause) when used. For syntax introduction, see [reference link](../select/#interp).
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- When there is no row data that meets the conditions at the specified time slice, the INTERP function will interpolate according to the settings of the [FILL](../distinguished/#FILL-Clause) parameter.
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- The input data for INTERP is the data of the specified column, which can be filtered through conditional statements (where clause). If no filtering condition is specified, the input is all data.
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- INTERP SQL queries need to be used together with the RANGE, EVERY, and FILL keywords; stream computing cannot use RANGE, needs EVERY and FILL keywords together.
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- When INTERP is applied to a supertable, it will sort all the subtable data under that supertable by primary key column and perform interpolation calculations, and can also be used with PARTITION BY tbname to force the results to a single timeline.
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- INTERP can be used with the pseudocolumn _irowts to return the timestamp corresponding to the interpolation point (supported from version 3.0.2.0).
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- INTERP can be used with the pseudocolumn _isfilled to display whether the return result is from the original record or generated by the interpolation algorithm (supported from version 3.0.3.0).
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- For queries on tables with composite primary keys, if there are data with the same timestamp, only the data with the smallest composite primary key participates in the calculation.
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- INTERP can only use the pseudocolumn `_irowts_origin` when using FILL PREV/NEXT/NEAR modes. `_irowts_origin` is supported from version 3.3.4.9.
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- For queries on tables with composite primary keys, if there are data with the same timestamp, only the data with the smallest composite primary key participates in the calculation.
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### IRATE
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@ -278,7 +278,8 @@ TDengine 支持基于时间戳主键的 INNER JOIN，规则如下：
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6. 不支持与 FILL 子句混合使用。
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## INTERP
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interp 子句配合 [INTERP](../function/#interp) 函数使用, 用于确定 INTERP 函数执行时，时间断面的截取规则和插值规则。
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interp 子句是 INTERP 函数(../function/#interp)的专用语法，当 SQL 语句中存在 interp 子句时，只能查询 INTERP 函数而不能与其他函数一起查询，同时 interp 子句与窗口子句(window_clause)、分组子句(group_by_clause)也不能同时使用。INTERP 函数在使用时需要与 RANGE、EVERY 和 FILL 子句一起使用；流计算不支持使用 RANGE，但需要与 EVERY 和 FILL 关键字一起使用。
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- INTERP 的输出时间范围根据 RANGE(timestamp1, timestamp2) 字段来指定，需满足 timestamp1 \<= timestamp2。其中 timestamp1 为输出时间范围的起始值，即如果 timestamp1 时刻符合插值条件则 timestamp1 为输出的第一条记录，timestamp2 为输出时间范围的结束值，即输出的最后一条记录的 timestamp 不能大于 timestamp2。
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- INTERP 根据 EVERY(time_unit) 字段来确定输出时间范围内的结果条数，即从 timestamp1 开始每隔固定长度的时间（time_unit 值）进行插值，time_unit 可取值时间单位：1a(毫秒)、1s(秒)、1m(分)、1h(小时)、1d(天)、1w(周)。例如 EVERY(500a) 将对于指定数据每500毫秒间隔进行一次插值。
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- INTERP 根据 FILL 字段来决定在每个符合输出条件的时刻如何进行插值。关于 FILL 子句如何使用请参考 [FILL 子句](./distinguished#fill-子句)
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@ -2122,14 +2122,14 @@ ignore_null_values: {
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**适用于**：表和超级表。
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**使用说明**
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- INTERP 用于在指定时间断面获取指定列的记录值，如果该时间断面不存在符合条件的行数据，那么会根据 [FILL](../distinguished/#fill-子句) 参数的设定进行插值。
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- INTERP 用于在指定时间断面获取指定列的记录值，使用时有专用语法(interp_clause)，语法介绍[参考链接](../select/#interp) 。
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- 当指定时间断面不存在符合条件的行数据时，INTERP 函数会根据 [FILL](../distinguished/#fill-子句) 参数的设定进行插值。
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- INTERP 的输入数据为指定列的数据，可以通过条件语句（where 子句）来对原始列数据进行过滤，如果没有指定过滤条件则输入为全部数据。
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- INTERP SQL 查询需要同时与 RANGE、EVERY 和 FILL 关键字一起使用；流计算不能使用 RANGE，需要 EVERY 和 FILL 关键字一起使用。使用规则见 [INTERP](../select/#interp) 子句。
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- INTERP 作用于超级表时，会将该超级表下的所有子表数据按照主键列排序后进行插值计算，也可以搭配 PARTITION BY tbname 使用，将结果强制规约到单个时间线。
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- INTERP 可以与伪列 `_irowts` 一起使用，返回插值点所对应的时间戳(v3.0.2.0 以后支持)。
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- INTERP 可以与伪列 `_isfilled` 一起使用，显示返回结果是否为原始记录或插值算法产生的数据(v3.0.3.0 以后支持)。
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- INTERP 只有在使用 [FILL](../distinguished/#fill-子句) PREV/NEXT/NEAR 模式时才可以使用伪列 `_irowts_origin`, 用于返回 `interp` 函数所使用的原始数据的时间戳列。若范围内无值, 则返回 NULL。`_irowts_origin` 在 v3.3.4.9 以后支持。
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- INTERP 对于带复合主键的表的查询，若存在相同时间戳的数据，则只有对应的复合主键最小的数据参与运算。
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- 只有在使用 FILL PREV/NEXT/NEAR 模式时才可以使用伪列 `_irowts_origin`, 用于返回 `interp` 函数所使用的原始数据的时间戳列。若范围内无值, 则返回 NULL。`_irowts_origin` 在 v3.3.4.9 以后支持。
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- 对于带复合主键的表的查询，若存在相同时间戳的数据，则只有对应的复合主键最小的数据参与运算。
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### IRATE
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