GBase 8c 函数和操作符 - HLL函数和操作符 之 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：

 --hll

gbase=# select (hll_empty() || hll_hash_integer(1)) = (hll_empty() || hll_hash_integer(1));

?column?

----------

 t

(1 row)

--hll_hashval

gbase=# 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：

 --hll

gbase=# select (hll_empty() || hll_hash_integer(1)) <> (hll_empty() || hll_hash_integer(2));

 ?column?

----------

 t

(1 row)

--hll_hashval

gbase=# 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：

 --hll_add

gbase=# select hll_empty() || hll_hash_integer(1);

                                  ?column?

----------------------------------------------------------------------------

 \x484c4c08000002002b0900000000000000f03f3e2921ff133fbaed3e2921ff133fbaed00

(1 row)

--hl_add_rev

gbase=# select hll_hash_integer(1) || hll_empty();

                                  ?column?

----------------------------------------------------------------------------

 \x484c4c08000002002b0900000000000000f03f3e2921ff133fbaed3e2921ff133fbaed00

(1 row)

--hll_union

gbase=# select (hll_empty() || hll_hash_integer(1)) || (hll_empty() || hll_hash_integer(2));

                                          ?column?

--------------------------------------------------------------------------------------------

 \x484c4c10002000002b090000000000000000400000000000000000b3ccc49320cca1ae3e2921ff133fbaed00

(1 row)

•  #

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

返回值类型：int

示例：

 gbase=# select #(hll_empty() || hll_hash_integer(1));

 ?column?

----------

        1

(1 row)