Help Center/ GaussDB(DWS)/ SQL Syntax Reference/ SQL Syntax Reference (8.1.3.x)/ Functions and Operators/ HLL Functions and Operators/ Hash Functions
Updated on 2024-09-03 GMT+08:00
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Hash Functions

hll_hash_boolean(bool)

Description: Hashes data of the bool type.

Return type: hll_hashval

Example: 
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SELECT hll_hash_boolean(FALSE);
  hll_hash_boolean   
---------------------
 5048724184180415669
(1 row)

hll_hash_boolean(bool, int32)

Description: Configures a hash seed (that is, change the hash policy) and hashes data of the bool type.

Return type: hll_hashval

Example:

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SELECT hll_hash_boolean(FALSE, 10);
  hll_hash_boolean  
--------------------
 391264977436098630
(1 row)

hll_hash_smallint(smallint)

Description: Hashes data of the smallint type.

Return type: hll_hashval

Example:

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SELECT hll_hash_smallint(100::smallint);
  hll_hash_smallint  
---------------------
 4631120266694327276
(1 row)

If parameters with the same numeric value are hashed using different data types, the data will differ, because hash functions select different calculation policies for each type.

hll_hash_smallint(smallint, int32)

Description: Configures a hash seed (that is, change the hash policy) and hashes data of the smallint type.

Return type: hll_hashval

Example:

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SELECT hll_hash_smallint(100::smallint, 10);
  hll_hash_smallint  
---------------------
 8349353095166695771
(1 row)

hll_hash_integer(integer)

Description: Hashes data of the integer type.

Return type: hll_hashval

Example:

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SELECT hll_hash_integer(0);
   hll_hash_integer   
----------------------
 -3485513579396041028
(1 row)

hll_hash_integer(integer, int32)

Description: Hashes data of the integer type and configures a hash seed (that is, change the hash policy).

Return type: hll_hashval

Example:

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 SELECT hll_hash_integer(0, 10);
  hll_hash_integer  
--------------------
 183371090322255134
(1 row)

hll_hash_bigint(bigint)

Description: Hashes data of the bigint type.

Return type: hll_hashval

Example:

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SELECT hll_hash_bigint(100::bigint);
   hll_hash_bigint   
---------------------
 8349353095166695771
(1 row)

hll_hash_bigint(bigint, int32)

Description: Hashes data of the bigint type and configures a hash seed (that is, change the hash policy).

Return type: hll_hashval

Example:

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SELECT hll_hash_bigint(100::bigint, 10);
   hll_hash_bigint   
---------------------
 4631120266694327276
(1 row)

hll_hash_bytea(bytea)

Description: Hashes data of the bytea type.

Return type: hll_hashval

Example:

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SELECT hll_hash_bytea(E'\\x');
 hll_hash_bytea 
----------------
 0
(1 row)

hll_hash_bytea(bytea, int32)

Description: Hashes data of the bytea type and configures a hash seed (that is, change the hash policy).

Return type: hll_hashval

Example:

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SELECT hll_hash_bytea(E'\\x', 10);
   hll_hash_bytea    
---------------------
 6574525721897061910
(1 row)

hll_hash_text(text)

Description: Hashes data of the text type.

Return type: hll_hashval

Example:

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SELECT hll_hash_text('AB');
    hll_hash_text    
---------------------
 5365230931951287672
(1 row)

hll_hash_text(text, int32)

Description: Hashes data of the text type and configures a hash seed (that is, change the hash policy).

Return type: hll_hashval

Example:

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SELECT hll_hash_text('AB', 10);
    hll_hash_text
---------------------
 7680762839921155903
(1 row)

hll_hash_any(anytype)

Description: Hashes data of any type.

Return type: hll_hashval

Example:

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SELECT hll_hash_any(1);
     hll_hash_any     
----------------------
 -8604791237420463362
(1 row)

SELECT hll_hash_any('08:00:2b:01:02:03'::macaddr);
     hll_hash_any     
----------------------
 -4883882473551067169
(1 row)

hll_hash_any(anytype, int32)

Description: Hashes data of any type and configures a hash seed (that is, change the hash policy).

Return type: hll_hashval

Example:

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SELECT hll_hash_any(1, 10);
     hll_hash_any     
----------------------
 -1478847531811254870
(1 row)

hll_hashval_eq(hll_hashval, hll_hashval)

Description: Compares two pieces of data of the hll_hashval type to check whether they are the same.

Return type: bool

Example:

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SELECT hll_hashval_eq(hll_hash_integer(1), hll_hash_integer(1));
 hll_hashval_eq 
----------------
 t
(1 row)

hll_hashval_ne(hll_hashval, hll_hashval)

Description: Compares two pieces of data of the hll_hashval type to check whether they are different.

Return type: bool

Example:

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SELECT hll_hashval_ne(hll_hash_integer(1), hll_hash_integer(1));
 hll_hashval_ne 
----------------
 f
(1 row)