Merge pull request #21527 from taosdata/feat/TS-3048

feat(query): support single point interp

docs/en/12-taos-sql/06-select.md

@@ -55,7 +55,7 @@ window_clause: {
   | INTERVAL(interval_val [, interval_offset]) [SLIDING (sliding_val)] [WATERMARK(watermark_val)] [FILL(fill_mod_and_val)]
 
 interp_clause:
-    RANGE(ts_val, ts_val) EVERY(every_val) FILL(fill_mod_and_val)
+    RANGE(ts_val [, ts_val]) EVERY(every_val) FILL(fill_mod_and_val)
 
 partition_by_clause:
     PARTITION BY expr [, expr] ...

docs/en/12-taos-sql/10-function.md

@@ -889,9 +889,10 @@ ignore_null_values: {
 - `INTERP` is used to get the value that matches the specified time slice from a column. If no such value exists an interpolation value will be returned based on `FILL` parameter.
 - The input data of `INTERP` is the value of the specified column and a `where` clause can be used to filter the original data. If no `where` condition is specified then all original data is the input.
 - `INTERP` must be used along with `RANGE`, `EVERY`, `FILL` keywords.
-- The output time range of `INTERP` is specified by `RANGE(timestamp1,timestamp2)` parameter, with timestamp1 <= timestamp2. timestamp1 is the starting point of the output time range and must be specified. timestamp2 is the ending point of the output time range and must be specified.
+- The output time range of `INTERP` is specified by `RANGE(timestamp1,timestamp2)` parameter, with timestamp1 <= timestamp2. timestamp1 is the starting point of the output time range. timestamp2 is the ending point of the output time range.
 - The number of rows in the result set of `INTERP` is determined by the parameter `EVERY(time_unit)`. Starting from timestamp1, one interpolation is performed for every time interval specified `time_unit` parameter. The parameter `time_unit` must be an integer, with no quotes, with a time unit of: a(millisecond)), s(second), m(minute), h(hour), d(day), or w(week). For example, `EVERY(500a)` will interpolate every 500 milliseconds.
 - Interpolation is performed based on `FILL` parameter. For more information about FILL clause, see [FILL Clause](../distinguished/#fill-clause).
+- When only one timestamp value is specified in `RANGE` clause, `INTERP` is used to generate interpolation at this point in time. In this case, `EVERY` clause can be omitted. For example, SELECT INTERP(col) FROM tb RANGE('2023-01-01 00:00:00') FILL(linear).
 - `INTERP` can be applied to supertable by interpolating primary key sorted data of all its childtables. It can also be used with `partition by tbname` when applied to supertable to generate interpolation on each single timeline.
 - Pseudocolumn `_irowts` can be used along with `INTERP` to return the timestamps associated with interpolation points(support after version 3.0.2.0).
 - Pseudocolumn `_isfilled` can be used along with `INTERP` to indicate whether the results are original records or data points generated by interpolation algorithm(support after version 3.0.3.0).
@@ -902,7 +903,7 @@ ignore_null_values: {
 - We want to downsample every 1 hour and use a linear fill for missing values. Note the order in which the "partition by" clause and the "range", "every" and "fill" parameters are used.
 
 ```sql
-SELECT _irowts,INTERP(current) FROM test.meters PARTITION BY TBNAME RANGE('2017-07-22 00:00:00','2017-07-24 12:25:00') EVERY(1h) FILL(LINEAR) 
+SELECT _irowts,INTERP(current) FROM test.meters PARTITION BY TBNAME RANGE('2017-07-22 00:00:00','2017-07-24 12:25:00') EVERY(1h) FILL(LINEAR)
 ```
 
 ### LAST

docs/zh/12-taos-sql/06-select.md

@@ -55,7 +55,7 @@ window_clause: {
   | INTERVAL(interval_val [, interval_offset]) [SLIDING (sliding_val)] [WATERMARK(watermark_val)] [FILL(fill_mod_and_val)]
 
 interp_clause:
-    RANGE(ts_val, ts_val) EVERY(every_val) FILL(fill_mod_and_val)
+    RANGE(ts_val [, ts_val]) EVERY(every_val) FILL(fill_mod_and_val)
 
 partition_by_clause:
     PARTITION BY expr [, expr] ...

docs/zh/12-taos-sql/10-function.md

@@ -890,9 +890,10 @@ ignore_null_values: {
 - 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 参数的设定进行插值。
 - 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。
 - INTERP 需要同时与 RANGE，EVERY 和 FILL 关键字一起使用。
-- 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（必选值）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（必选值）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。
+- 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。
 - 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.
 - 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)
+- INTERP 可以在 RANGE 字段中只指定唯一的时间戳对单个时间点进行插值，在这种情况下，EVERY 字段可以省略。例如：SELECT INTERP(col) FROM tb RANGE('2023-01-01 00:00:00') FILL(linear).
 - 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。
 - INTERP 可以与伪列 _irowts 一起使用，返回插值点所对应的时间戳(3.0.2.0版本以后支持)。
 - 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(3.0.3.0版本以后支持)。

source/libs/parser/inc/parAst.h

@@ -127,6 +127,7 @@ SNode* createIntervalWindowNode(SAstCreateContext* pCxt, SNode* pInterval, SNode
 SNode* createFillNode(SAstCreateContext* pCxt, EFillMode mode, SNode* pValues);
 SNode* createGroupingSetNode(SAstCreateContext* pCxt, SNode* pNode);
 SNode* createInterpTimeRange(SAstCreateContext* pCxt, SNode* pStart, SNode* pEnd);
+SNode* createInterpTimePoint(SAstCreateContext* pCxt, SNode* pPoint);
 SNode* createWhenThenNode(SAstCreateContext* pCxt, SNode* pWhen, SNode* pThen);
 SNode* createCaseWhenNode(SAstCreateContext* pCxt, SNode* pCase, SNodeList* pWhenThenList, SNode* pElse);
 

source/libs/parser/inc/sql.y

@@ -1095,6 +1095,8 @@ having_clause_opt(A) ::= HAVING search_condition(B).
 range_opt(A) ::= .                                                                { A = NULL; }
 range_opt(A) ::=
   RANGE NK_LP expr_or_subquery(B) NK_COMMA expr_or_subquery(C) NK_RP.             { A = createInterpTimeRange(pCxt, releaseRawExprNode(pCxt, B), releaseRawExprNode(pCxt, C)); }
+range_opt(A) ::=
+  RANGE NK_LP expr_or_subquery(B) NK_RP.                                          { A = createInterpTimePoint(pCxt, releaseRawExprNode(pCxt, B)); }
 
 every_opt(A) ::= .                                                                { A = NULL; }
 every_opt(A) ::= EVERY NK_LP duration_literal(B) NK_RP.                           { A = releaseRawExprNode(pCxt, B); }

source/libs/parser/src/parAstCreater.c

@@ -695,6 +695,11 @@ SNode* createInterpTimeRange(SAstCreateContext* pCxt, SNode* pStart, SNode* pEnd
   return createBetweenAnd(pCxt, createPrimaryKeyCol(pCxt, NULL), pStart, pEnd);
 }
 
+SNode* createInterpTimePoint(SAstCreateContext* pCxt, SNode* pPoint) {
+  CHECK_PARSER_STATUS(pCxt);
+  return createOperatorNode(pCxt, OP_TYPE_EQUAL, createPrimaryKeyCol(pCxt, NULL), pPoint);
+}
+
 SNode* createWhenThenNode(SAstCreateContext* pCxt, SNode* pWhen, SNode* pThen) {
   CHECK_PARSER_STATUS(pCxt);
   SWhenThenNode* pWhenThen = (SWhenThenNode*)nodesMakeNode(QUERY_NODE_WHEN_THEN);

source/libs/parser/src/parTranslater.c

@@ -3497,6 +3497,22 @@ static int32_t createDefaultFillNode(STranslateContext* pCxt, SNode** pOutput) {
   return TSDB_CODE_SUCCESS;
 }
 
+static int32_t createDefaultEveryNode(STranslateContext* pCxt, SNode** pOutput) {
+  SValueNode* pEvery = (SValueNode*)nodesMakeNode(QUERY_NODE_VALUE);
+  if (NULL == pEvery) {
+    return TSDB_CODE_OUT_OF_MEMORY;
+  }
+
+  pEvery->node.resType.type = TSDB_DATA_TYPE_BIGINT;
+  pEvery->node.resType.bytes = tDataTypes[TSDB_DATA_TYPE_BIGINT].bytes;
+  pEvery->isDuration = true;
+  pEvery->literal = taosStrdup("1s");
+
+
+  *pOutput = (SNode*)pEvery;
+  return TSDB_CODE_SUCCESS;
+}
+
 static int32_t checkEvery(STranslateContext* pCxt, SValueNode* pInterval) {
   int32_t len = strlen(pInterval->literal);
 
@@ -3512,7 +3528,12 @@ static int32_t checkEvery(STranslateContext* pCxt, SValueNode* pInterval) {
 static int32_t translateInterpEvery(STranslateContext* pCxt, SNode** pEvery) {
   int32_t code = TSDB_CODE_SUCCESS;
 
-  code = checkEvery(pCxt, (SValueNode*)(*pEvery));
+  if (NULL == *pEvery) {
+    code = createDefaultEveryNode(pCxt, pEvery);
+  }
+  if (TSDB_CODE_SUCCESS == code) {
+    code = checkEvery(pCxt, (SValueNode*)(*pEvery));
+  }
   if (TSDB_CODE_SUCCESS == code) {
     code = translateExpr(pCxt, pEvery);
   }
@@ -3558,8 +3579,12 @@ static int32_t translateInterp(STranslateContext* pCxt, SSelectStmt* pSelect) {
   }
 
   if (NULL == pSelect->pRange || NULL == pSelect->pEvery || NULL == pSelect->pFill) {
-    return generateSyntaxErrMsgExt(&pCxt->msgBuf, TSDB_CODE_PAR_INVALID_INTERP_CLAUSE,
-                                   "Missing RANGE clause, EVERY clause or FILL clause");
+    if (pSelect->pRange != NULL && QUERY_NODE_OPERATOR == nodeType(pSelect->pRange) && pSelect->pEvery == NULL) {
+      // single point interp every can be omitted
+    } else {
+      return generateSyntaxErrMsgExt(&pCxt->msgBuf, TSDB_CODE_PAR_INVALID_INTERP_CLAUSE,
+                                     "Missing RANGE clause, EVERY clause or FILL clause");
+    }
   }
 
   int32_t code = translateExpr(pCxt, &pSelect->pRange);
@@ -3786,7 +3811,7 @@ static int32_t translateSelectFrom(STranslateContext* pCxt, SSelectStmt* pSelect
   if (TSDB_CODE_SUCCESS == code) {
     code = replaceTbName(pCxt, pSelect);
   }
-  
+
   return code;
 }