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8 Commits

Author SHA1 Message Date
Hao Tan
c71f58fef9 [Doc] Add sidebar for percentile doc (#6470) 2021-08-22 22:03:07 +08:00
Hao Tan
66a7a4b294 [Feature] Support exact percentile aggregate function (#6410) 
Support to calculate the exact percentile value array of numeric column `col` at the given percentage(s).
 2021-08-18 15:56:06 +08:00
Youngwb
650536d53e [Feature] Add Topn udaf (#4803) 
For #4674 
This is a udaf for approximate topn using Space-Saving algorithm.  At present, we can only calculate
the frequent items and their frequencies in a certain column, based on which we can implement similar
topN functions supported by Kylin in the future. 

I have also added a test to calculate the accuracy of this algorithm. The following is a rough running result.
The total amount of data is 1 million lines and follows the Zipfian distribution, where Element Cardinality
represents the data cardinality, 20X, 50X.. The value representing space_expand_rate is 20,50, which is
used to set the counter number in the space-saving algorithm

```
zf exponent = 0.5
Element cardinality	        20X        50X          100X
               1000		100%	   100%         100%
               10000		100%	   100%		100%
	       100000		100%	   100%		100%
	       500000		 94%	    98%		 99%

zf exponent = 0.6，1
Element cardinality	        20X        50X          100X
		1000		100%	   100%         100%
		10000		100%	   100%		100%
		100000		100%	   100%		100%
		500000		100%	   100%		100%

```
 2020-12-16 21:58:34 +08:00
Mingyu Chen
a95ce69c0d [Doc] Bug fix that help commend not work (#4760) 
There are 2 docs with same name "bitmap", which cause error
when building help system.
 2020-10-20 09:47:51 +08:00
Zhengguo Yang
751aa05cc0 fix docs typo (#4725) 2020-10-14 09:27:50 +08:00
ZhangYu0123
1d9b3aeee7 [Doc] Repair document format (#4336) 
The error format '##keyword' in a lot of docs. This pr is to repair document format. #4335
 2020-08-13 23:39:41 +08:00
HangyuanLiu
116d7ffa3c [SQL][Function] Add approx_count_distinct() function (#4221) 
Add approx_count_distinct() function to replace the ndv() function
 2020-08-01 17:54:19 +08:00
hffariel
432965e360 [Enhancement] documents rebuild with Vuepress (#3408) (#3414) 2020-04-29 09:14:31 +08:00