更新时间:2025-05-29 GMT+08:00

操作符

=

描述:比较hll或hll_hashval的值是否相等。

返回值类型:bool

示例:

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--hll
gaussdb=# SELECT (hll_empty() || hll_hash_integer(1)) = (hll_empty() || hll_hash_integer(1));
column 
----------
 t
(1 row)

--hll_hashval
gaussdb=# SELECT hll_hash_integer(1) = hll_hash_integer(1);
 ?column? 
----------
 t
(1 row)

<> or !=

描述:比较hll或hll_hashval是否不相等。

返回值类型:bool

示例:

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--hll
gaussdb=# SELECT (hll_empty() || hll_hash_integer(1)) <> (hll_empty() || hll_hash_integer(2));
 ?column? 
----------
 t
(1 row)

--hll_hashval
gaussdb=# SELECT hll_hash_integer(1) <> hll_hash_integer(2);
 ?column? 
----------
 t
(1 row)

||

描述:可代表hll_add, hll_union, hll_add_rev三个函数的功能。

返回值类型:hll

示例:

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--hll_add
gaussdb=# SELECT hll_empty() || hll_hash_integer(1);
                                  ?column?
----------------------------------------------------------------------------
 \x484c4c08000002002b0900000000000000f03f3e2921ff133fbaed3e2921ff133fbaed00
(1 row)

--hll_add_rev
gaussdb=# SELECT hll_hash_integer(1) || hll_empty();
                                  ?column?
----------------------------------------------------------------------------
 \x484c4c08000002002b0900000000000000f03f3e2921ff133fbaed3e2921ff133fbaed00
(1 row)

--hll_union
gaussdb=# SELECT (hll_empty() || hll_hash_integer(1)) || (hll_empty() || hll_hash_integer(2));
                                          ?column?
--------------------------------------------------------------------------------------------
 \x484c4c10002000002b090000000000000000400000000000000000b3ccc49320cca1ae3e2921ff133fbaed00
(1 row)

#

描述:计算出hll的distinct值,同hll_cardinality函数。

返回值类型:int

示例:

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gaussdb=# SELECT #(hll_empty() || hll_hash_integer(1));
 ?column? 
----------
        1
(1 row)