支持asofjoin算子 · Pull Request !6480 · openGauss/openGauss-server

【标题】(请简要描述下实现的内容)
 新增asof join连接类型，加速时间序列连接
【实现内容】:
 在数据分析的业务场景下，时间数据的处理在很多行业的使用非常频繁，该特性的添加将至少带来2倍性能的提升。 很多商业和开源的数据引擎已经添加了该特性
【根因分析】:
 时间序列数据并不总是完美对齐。时钟可能略有偏差，或者原因和结果之间可能存在延迟。导致连接两组有序数据变得困难。 本方案优化通过使用窗口函数构造状态表进行连接的方案
 ```
  WITH state AS (
  SELECT ticker, price, "when",
    LEAD("when", 1, 'infinity') OVER (PARTITION BY ticker ORDER BY "when") AS end
  FROM prices
)

SELECT h.ticker, h.when, price * shares AS value
FROM holdings h INNER JOIN state s
  ON h.ticker = s.ticker
 AND h.when >= s.when
 AND h.when < s.end;
```
通过添加asojoin连接类型加速时间序列连接
```
SELECT h.ticker, h.when, price * shares AS value
FROM holdings h ASOF JOIN prices p
  ON h.ticker = p.ticker
 AND h.when >= p.when;
```
【实现方案】:
 流程示意图
 ![输入图片说明](https://foruda.gitee.com/images/1721185017265363901/93450b34_12734611.png "屏幕截图")
 方案原理图
 ![输入图片说明](https://foruda.gitee.com/images/1721185038109155613/594fc5ac_12734611.png "屏幕截图")

【关联需求或issue】:
https://gitee.com/opengauss/openGauss-server/issues/IAHMCE
【开发自验报告】:
1. 请附上自验结果(内容或者截图)
  ![输入图片说明](https://foruda.gitee.com/images/1721185149582801866/0abecb9f_12734611.png "屏幕截图")
  ![输入图片说明](https://foruda.gitee.com/images/1721185168196904137/ac97d847_12734611.png "屏幕截图")
2. 是否可以添加fastcheck测试用例，如是，请补充fastcheck用例
  ```
   ---
--- Normal Case
----
set query_dop = 1;
SELECT h.ticker, h.wh, price * shares AS total 
FROM holdings h 
ASOF JOIN prices p ON h.ticker = p.ticker AND h.wh >= p.wh order by h.ticker;

explain (verbose on, costs off) 
SELECT h.ticker, h.wh, price * shares AS total 
FROM holdings h 
ASOF JOIN prices p ON h.ticker = p.ticker AND h.wh >= p.wh order by h.ticker;

SELECT h.ticker, h.wh
FROM (
  SELECT ticker, 
   wh,
   pa
  FROM holdings 
)  h ASOF JOIN (
  SELECT ticker, 
   wh,
   pa
  FROM prices
) p
  ON h.ticker = p.ticker AND h.pa = p.pa  AND h.wh >= p.wh order by h.ticker;

SELECT h.ticker, h.wh
FROM (
  SELECT ticker, 
   wh, 
   pa+1 as pas
  FROM holdings
)  h ASOF JOIN (
  SELECT ticker, 
   wh, 
   pa+1 as pas
  FROM prices
) p
  ON h.ticker = p.ticker  AND h.wh >= p.wh AND h.pas >= p.pas order by h.ticker;

-- SMP case
set query_dop = 2;
SELECT h.ticker, h.wh, price * shares AS total 
FROM holdings h 
ASOF JOIN prices p ON h.ticker = p.ticker AND h.wh >= p.wh order by h.ticker;
explain (verbose on, costs off)
SELECT h.ticker, h.wh, price * shares AS total 
FROM holdings h 
ASOF JOIN prices p ON h.ticker = p.ticker AND h.wh >= p.wh order by h.ticker;
```
3. 是否涉及资料修改，如是，在docs仓库补充资料
4. 是否考虑升级场景(系统表修改、日志持久化以及修改执行态数据格式)
5. 是否考虑在线扩容等扩展场景
5. 是否考虑异常场景/并发场景/前向兼容/性能场景
6. 是否对其他模块产生影响

【其他说明】:

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