Hash Functions
- bucketabstime (value, flag)
Description: Hashes the value in the abstime format and finds the corresponding hash bucket.
Parameter: value indicates the value to be converted, which is of the abstime type. flag is of the int type, indicating the data distribution mode. The value 0 indicates hash distribution.
Return type: int32
Example:
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gaussdb=# SELECT bucketabstime('2011-10-01 10:10:10.112',1); bucketabstime --------------- 13954 (1 row)
- bucketbool (value, flag)
Description: Hashes the value in the bool format and finds the corresponding hash bucket.
Parameter: value indicates the value to be converted, which is of the bool type. flag is of the int type, indicating the data distribution mode. The value 0 indicates hash distribution.
Return type: int32
Example:
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gaussdb=# SELECT bucketbool(true,1); bucketbool ------------ 1 (1 row) gaussdb=# SELECT bucketbool(false,1); bucketbool ------------ 0 (1 row)
- bucketbpchar(value, flag)
Description: Hashes the value in the bpchar format and finds the corresponding hash bucket.
Parameter: value indicates the value to be converted, which is of the bpchar type. flag is of the int type, indicating the data distribution mode. The value 0 indicates hash distribution.
Return type: int32
Example:
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gaussdb=# SELECT bucketbpchar('test',1); bucketbpchar -------------- 9761 (1 row)
- bucketbytea (value, flag)
Description: Hashes the value in the bytea format and finds the corresponding hash bucket.
Parameter: value indicates the value to be converted, which is of the bytea type. flag is of the int type, indicating the data distribution mode. The value 0 indicates hash distribution.
Return type: int32
Example:
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gaussdb=# SELECT bucketbytea('test',1); bucketbytea ------------- 9761 (1 row)
- bucketcash (value, flag)
Description: Hashes the value in the money format and finds the corresponding hash bucket.
Parameter: value indicates the value to be converted, which is of the money type. flag is of the int type, indicating the data distribution mode. The value 0 indicates hash distribution.
Return type: int32
Example:
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gaussdb=# SELECT bucketcash(10::money,1); bucketcash ------------ 8468 (1 row)
- getbucket (value, flag)
Description: Obtains the hash bucket from the distribution key.
value indicates the value to be entered, which can be of the following types:
"char", abstime, bigint, boolean,bytea, character varying, character, date, double precision, int2vector, integer, interval, money, name, numeric, nvarchar2, oid, oidvector, raw, real, record, reltime, smalldatetime, smallint,text, time with time zone, time without time zone, timestamp with time zone, timestamp without time zone, tinyint, uuid
flag is of the int type, indicating the data distribution mode.
Return type: integer
Example:
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gaussdb=# SELECT getbucket(10,'H'); getbucket ----------- 14535 (1 row) gaussdb=# SELECT getbucket(11,'H'); getbucket ----------- 13449 (1 row) gaussdb=# SELECT getbucket(11,'R'); getbucket ----------- 13449 (1 row) gaussdb=# SELECT getbucket(12,'R'); getbucket ----------- 9412 (1 row)
- ora_hash(expression,[seed])
Description: Calculates the hash value of a given expression. expression: The value can be a character string, time, or number. The hash value is calculated based on the expression. seed: an int8 value that can return different results for the same input value. This parameter is optional and is used to calculate the hash value with a random number.
Return type: hash value of the int8 type.
Example:
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gaussdb=# SELECT ora_hash(123); ora_hash ------------ 4089882933 (1 row) gaussdb=# SELECT ora_hash('123'); ora_hash ------------ 2034089965 (1 row) gaussdb=# SELECT ora_hash('sample'); ora_hash ------------ 1573005290 (1 row) gaussdb=# SELECT ora_hash(to_date('2012-1-2','yyyy-mm-dd')); ora_hash ------------ 1171473495 (1 row) gaussdb=# SELECT ora_hash(123,234); ora_hash ------------ -9089505052966355682 (1 row) gaussdb=# SELECT ora_hash('123',234); ora_hash ------------ 5742589019960764616 (1 row) gaussdb=# SELECT ora_hash('sample',234); ora_hash ------------ -1747984408055821656 (1 row) gaussdb=# SELECT ora_hash(to_date('2012-1-2','yyyy-mm-dd'),234); ora_hash ------------ -3306025179710572679 (1 row)
This function is valid only when a_format_version is set to 10c and a_format_dev_version is set to s2.
- hash_array(anyarray)
Description: Hashes an array, obtains the result of an array element using the hash function, and returns the combination result.
Parameter: data of the anyrange type.
Return type: integer
Example:
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gaussdb=# SELECT hash_array(ARRAY[[1,2,3],[1,2,3]]); hash_array ------------ -382888479 (1 row)
- hash_numeric(numeric)
Description: Calculates the hash value of numeric data.
Parameter: data of the numeric type.
Return type: integer
Example:
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gaussdb=# SELECT hash_numeric(30); hash_numeric -------------- -282860963 (1 row)
- hash_range(anyrange)
Description: Calculates the hash value of a range.
Parameter: data of the anyrange type.
Return type: integer
Example:
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gaussdb=# SELECT hash_range(numrange(1.1,2.2)); hash_range ------------ 683508754 (1 row)
- hashbpchar(character)
Description: Calculates the hash value of bpchar.
Parameter: data of the character type.
Return type: integer
Example:
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gaussdb=# SELECT hashbpchar('hello'); hashbpchar ------------- -1870292951 (1 row)
- hashchar(char)
Description: Converts char and Boolean data into hash values.
Parameter: data of the char or bool type.
Return type: integer
Example:
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gaussdb=# SELECT hashbpchar('hello'); hashbpchar ------------- -1870292951 (1 row) gaussdb=# SELECT hashchar('true'); hashchar ------------ 1686226652 (1 row)
- hashenum(anyenum)
Description: Converts enumerated values to hash values.
Parameter: data of the anyenum type.
Return type: integer
Example:
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gaussdb=# CREATE TYPE b1 AS ENUM('good', 'bad', 'ugly'); CREATE TYPE gaussdb=# call hashenum('good'::b1); hashenum ------------ 1821213359 (1 row)
- hashfloat4(real)
Description: Converts float4 values to hash values.
Parameter: data of the real type.
Return type: integer
Example:
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gaussdb=# SELECT hashfloat4(12.1234); hashfloat4 ------------ 1398514061 (1 row)
- hashfloat8(double precision)
Description: Converts float8 values to hash values.
Parameter: data of the double precision type.
Return type: integer
Example:
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gaussdb=# SELECT hashfloat8(123456.1234); hashfloat8 ------------ 1673665593 (1 row)
- hashinet(inet)
Description: Converts inet or cidr values to hash values.
Parameter: data of the inet type.
Return type: integer
Example:
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gaussdb=# SELECT hashinet('127.0.0.1'::inet); hashinet ------------- -1435793109 (1 row)
- hashint1(tinyint)
Description: Converts INT1 values to hash values.
Parameter: data of the tinyint type.
Return type: uint32
Example:
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gaussdb=# SELECT hashint1(20); hashint1 ------------- -2014641093 (1 row)
- hashint2(smallint)
Description: Converts INT2 values to hash values.
Parameter: data of the smallint type.
Return type: uint32
Example:
gaussdb=# SELECT hashint2(20000); hashint2 ------------ -863179081 (1 row) - bucketchar()
Description: Calculates the hash value of the input parameter.
Parameter: char, integer
Return type: integer
- bucketdate()
Description: Calculates the hash value of the input parameter.
Parameter: date, integer
Return type: integer
- bucketfloat4()
Description: Calculates the hash value of the input parameter.
Parameter: real, integer
Return type: integer
- bucketfloat8()
Description: Calculates the hash value of the input parameter.
Parameters: double precision, integer
Return type: integer
- bucketint1()
Description: Calculates the hash value of the input parameter.
Parameter: tinyint, integer
Return type: integer
- bucketint2()
Description: Calculates the hash value of the input parameter.
Parameter: smallint, integer
Return type: integer
- bucketint2vector()
Description: Calculates the hash value of the input parameter.
Parameter: int2vector, integer
Return type: integer
- bucketint4()
Description: Calculates the hash value of the input parameter.
Parameter: integer, integer
Return type: integer
- bucketint8()
Description: Calculates the hash value of the input parameter.
Parameter: bigint, integer
Return type: integer
- bucketinterval()
Description: Calculates the hash value of the input parameter.
Parameter: interval, integer
Return type: integer
- bucketname()
Description: Calculates the hash value of the input parameter.
Parameter: name, integer
Return type: integer
- bucketnumeric()
Description: Calculates the hash value of the input parameter.
Parameter: numeric, integer
Return type: integer
- bucketnvarchar2()
Description: Calculates the hash value of the input parameter.
Parameter: nvarchar2, integer
Return type: integer
- bucketoid()
Description: Calculates the hash value of the input parameter.
Parameters: oid, integer
Return type: integer
- bucketoidvector()
Description: Calculates the hash value of the input parameter.
Parameter: oidvector, integer
Return type: integer
- bucketraw()
Description: Calculates the hash value of the input parameter.
Parameter: raw, integer
Return type: integer
- bucketreltime()
Description: Calculates the hash value of the input parameter.
Parameter: reltime, integer
Return type: integer
- bucketsmalldatetime()
Description: Calculates the hash value of the input parameter.
Parameter: smalldatetime, integer
Return type: integer
- buckettext()
Description: Calculates the hash value of the input parameter.
Parameter: text, integer
Return type: integer
- buckettime()
Description: Calculates the hash value of the input parameter.
Parameter: time without time zone, integer
Return type: integer
- buckettimestamp()
Description: Calculates the hash value of the input parameter.
Parameter: timestamp without time zone, integer
Return type: integer
- buckettimestamptz()
Description: Calculates the hash value of the input parameter.
Parameter: timestamp with time zone, integer
Return type: integer
- buckettimetz()
Description: Calculates the hash value of the input parameter.
Parameter: time with time zone, integer
Return type: integer
- bucketuuid()
Description: Calculates the hash value of the input parameter.
Parameter: uuid, integer
Return type: integer
- bucketvarchar()
Description: Calculates the hash value of the input parameter.
Parameter: character varying, integer
Return type: integer
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