Built-in Functions¶
HyperLogLog (HLL) has a series of built-in functions for internal data processing. Generally, you are not advised to use these functions.
Function | Function |
---|---|
hll_in | Receives hll data in string format. |
hll_out | Sends hll data in string format. |
hll_recv | Receives hll data in bytea format. |
hll_send | Sends hll data in bytea format. |
hll_trans_in | Receives hll_trans_type data in string format. |
hll_trans_out | Sends hll_trans_type data in string format. |
hll_trans_recv | Receives hll_trans_type data in bytea format. |
hll_trans_send | Sends hll_trans_type data in bytea format. |
hll_typmod_in | Receives typmod data. |
hll_typmod_out | Sends typmod data. |
hll_hashval_in | Receives hll_hashval data. |
hll_hashval_out | Sends hll_hashval data. |
hll_add_trans0 | Works similar to hll_add, and is used on the first phase of DNs in distributed aggregation operations. |
hll_union_trans | Works similar to hll_union, and is used on the first phase of DNs in distributed aggregation operations. |
hll_union_collect | Works similar to hll_union, and is used on the second phase of CNs in distributed aggregation operations to summarize the results of each DN. |
hll_pack | Is used on the third phase of CNs in distributed aggregation operations to convert a user-defined type hll_trans_type to the hll type. |
hll | Converts a hll type to another hll type. Input parameters can be specified. |
hll_hashval | Converts the bigint type to the hll_hashval type. |
hll_hashval_int4 | Converts the int4 type to the hll_hashval type. |