com.vertica.jdbc.kv

Class VHash

java.lang.Object

com.vertica.jdbc.kv.VHash

Deprecated.

This feature is likely to stop working in a future release and to be removed as a result.

@Deprecated
public class VHash
extends java.lang.Object

Implementation of Vertica's hash function used for data segmentation on the cluster. For single-value hashing, use static methods. For multi-value hashing, instantiate the class and call the add methods to add each value (order matters).

Constructor Summary

Constructors

Constructor and Description
VHash() Deprecated. Creates an instance suitable for computing a hash of a chain of values, for use when a projection is segmented by multiple columns.

Method Summary

Modifier and Type	Method and Description
void	addBoolean(boolean v) Deprecated. adds hash of boolean value to the chain.
void	addBooleanNull() Deprecated. adds hash of boolean null value to the chain.
void	addBytes(byte[] v) Deprecated. adds hash of binary value to the chain.
void	addDate(java.util.Date v, java.util.Calendar c) Deprecated. adds hash of Date value to the chain.
void	addDate(java.sql.Date v, java.util.Calendar c) Deprecated. adds hash of Date value to the chain.
void	addDouble(double v) Deprecated. adds hash of double value to the chain.
void	addDoubleNull() Deprecated. adds hash of double null value to the chain.
void	addLong(long v) Deprecated. adds hash of long value to the chain.
void	addNull() Deprecated. Adds hash of null value to the chain.
void	addNumeric(java.math.BigDecimal src, int typemod) Deprecated. adds hash of numeric value to the chain
void	addString(java.lang.String v) Deprecated. adds hash of String value to the chain.
void	addTime(java.util.Date v, java.util.Calendar c) Deprecated. adds hash of Time value to the chain.
void	addTime(java.sql.Time v, java.util.Calendar c) Deprecated. adds hash of Time value to the chain.
void	addTimestamp(java.util.Date v, java.util.Calendar c) Deprecated. adds hash of Timestamp value to the chain.
void	addTimestamp(long v) Deprecated. adds hash of Timestamp value expressed as milliseconds since Jan 1, 1970 UTC to the chain.
void	addTimestamp(java.sql.Timestamp v, java.util.Calendar c) Deprecated. adds hash of Timestamp value to the chain.
void	addUUID(java.util.UUID v) Deprecated. adds hash of UUID value to the chain.
void	addUUIDNull() Deprecated. adds hash of null UUID to the chain.
long	getHash() Deprecated. returns the current hash value
static java.lang.String	getNodeFor(java.sql.Connection conn, java.lang.String schema, java.lang.String proj, long hashValue) Deprecated. Returns the name of the node that will be responsible for the provided value in the hash space for a given projection.
static java.lang.String	getNodeFor(java.lang.String getProjSegmentsOutput, long hashValue) Deprecated. Given a projection's get_projection_segments() output, this method will return the node that is responsible for the provided hashValue.
static long	hashBoolean(boolean v) Deprecated. compute hash of boolean value
static long	hashBooleanNull() Deprecated. compute hash of boolean null value
static long	hashBytes(byte[] b) Deprecated. compute hash of a binary value
static long	hashBytesNull() Deprecated. compute hash of a binary null value
static long	hashBytesNull(long input) Deprecated. compute hash of a binary null value
static long	hashDate(java.util.Date v) Deprecated. compute hash of java.util.Date value
static long	hashDate(java.sql.Date v) Deprecated. compute hash of java.sql.Date value
static long	hashDouble(double v) Deprecated. compute hash of double value
static long	hashDoubleNull() Deprecated. compute hash of double null value
static long	hashLong(long v) Deprecated. compute hash of long value
static long	hashNull() Deprecated. Compute hash of null value
static long	hashNull(long input) Deprecated. compute hash of null value.
static long	hashNumeric(java.math.BigDecimal src, int typemod) Deprecated. compute hash of a numeric value
static long	hashString(java.lang.String s) Deprecated. compute hash of String value
static long	hashStringNull() Deprecated. compute hash of String null value
static long	hashTime(java.sql.Time v) Deprecated. compute hash of Time value
static long	hashTimestamp(long java_ms) Deprecated. compute hash of Timestamp value expressed in milliseconds since Jan 1, 1970.
static long	hashTimestamp(java.sql.Timestamp v) Deprecated. compute hash of java.sql.Timestamp value
static long	hashUUID(java.util.UUID v, long input) Deprecated. compute hash of UUID value.
static long	hashUUIDNull() Deprecated. compute a hash of a null UUID value.
static long	hashUUIDNull(long input) Deprecated. compute a hash of a null UUID value.
void	reset() Deprecated. resets hash value for next chain.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

VHash

public VHash()

Deprecated.

Creates an instance suitable for computing a hash of a chain of values, for use when a projection is segmented by multiple columns.

Method Detail

hashBooleanNull

public static long hashBooleanNull()

Deprecated.

compute hash of boolean null value

Returns:

long hash value

hashBoolean

public static long hashBoolean(boolean v)

Deprecated.

compute hash of boolean value

Parameters:

v - boolean value to hash

Returns:

long hash value

hashLong

public static long hashLong(long v)

Deprecated.

compute hash of long value

Parameters:

v - long value to hash

Returns:

long hash value

hashNull

public static long hashNull(long input)

Deprecated.

compute hash of null value. First argument used to hash a list of values.

Parameters:

input - long value from previous hash function output

Returns:

long hash value

hashNull

public static long hashNull()

Deprecated.

Compute hash of null value

Returns:

long hash value

hashUUID

public static long hashUUID(java.util.UUID v,
                            long input)

Deprecated.

compute hash of UUID value.

Parameters:

v - fixed binary value to hash

input - variable input value to hash

Returns:

long hash value

hashUUIDNull

public static long hashUUIDNull(long input)

Deprecated.

compute a hash of a null UUID value. First argument used to hash a list of values.

Parameters:

input - long value from previous hash function output

Returns:

The hash for null UUID.

hashUUIDNull

public static long hashUUIDNull()

Deprecated.

compute a hash of a null UUID value.

Returns:

The hash for null UUID.

hashDouble

public static long hashDouble(double v)

Deprecated.

compute hash of double value

Parameters:

v - double value to hash

Returns:

long hash value

hashDoubleNull

public static long hashDoubleNull()

Deprecated.

compute hash of double null value

Returns:

long hash value

hashTimestamp

public static long hashTimestamp(long java_ms)

Deprecated.

compute hash of Timestamp value expressed in milliseconds since Jan 1, 1970.

Parameters:

java_ms - A number of milliseconds since Jan 1, 1970 GMT

Returns:

long hash value

hashDate

public static long hashDate(java.util.Date v)

Deprecated.

compute hash of java.util.Date value

Parameters:

v - Date value to hash

Returns:

long hash value

hashDate

public static long hashDate(java.sql.Date v)

Deprecated.

compute hash of java.sql.Date value

Parameters:

v - Date value to hash

Returns:

long hash value

hashTimestamp

public static long hashTimestamp(java.sql.Timestamp v)

Deprecated.

compute hash of java.sql.Timestamp value

Parameters:

v - Timestamp value to hash

Returns:

long hash value

hashTime

public static long hashTime(java.sql.Time v)

Deprecated.

compute hash of Time value

Parameters:

v - Time value to hash

Returns:

long hash value

hashString

public static long hashString(java.lang.String s)

Deprecated.

compute hash of String value

Parameters:

s - String value to hash

Returns:

long hash value

hashStringNull

public static long hashStringNull()

Deprecated.

compute hash of String null value

Returns:

long hash value

hashBytesNull

public static long hashBytesNull()

Deprecated.

compute hash of a binary null value

Returns:

long hash value

hashBytesNull

public static long hashBytesNull(long input)

Deprecated.

compute hash of a binary null value

Parameters:

input - long value from previous hash function output

Returns:

long hash value

hashBytes

public static long hashBytes(byte[] b)

Deprecated.

compute hash of a binary value

Parameters:

b - binary value to hash

Returns:

long hash value

hashNumeric

public static long hashNumeric(java.math.BigDecimal src,
                               int typemod)

Deprecated.

compute hash of a numeric value

Parameters:

src - Numeric value to hash

typemod - The precision and scale of the numeric.

Returns:

long hash value

reset

public void reset()

Deprecated.

resets hash value for next chain.

addNull

public void addNull()

Deprecated.

Adds hash of null value to the chain. Use hashBooleanNull() to hash a boolean null.

addBoolean

public void addBoolean(boolean v)

Deprecated.

adds hash of boolean value to the chain.

Parameters:

v - boolean value to hash

addBooleanNull

public void addBooleanNull()

Deprecated.

adds hash of boolean null value to the chain.

addLong

public void addLong(long v)

Deprecated.

adds hash of long value to the chain.

Parameters:

v - long value to hash

addUUID

public void addUUID(java.util.UUID v)

Deprecated.

adds hash of UUID value to the chain.

Parameters:

v - fixed binary value to hash

addUUIDNull

public void addUUIDNull()

Deprecated.

adds hash of null UUID to the chain.

addString

public void addString(java.lang.String v)

Deprecated.

adds hash of String value to the chain.

Parameters:

v - String value to hash

addBytes

public void addBytes(byte[] v)

Deprecated.

adds hash of binary value to the chain.

Parameters:

v - String value to hash

addTimestamp

public void addTimestamp(long v)

Deprecated.

adds hash of Timestamp value expressed as milliseconds since Jan 1, 1970 UTC to the chain.

Parameters:

v - long value to hash

addDate

public void addDate(java.util.Date v,
                    java.util.Calendar c)

Deprecated.

adds hash of Date value to the chain.

Parameters:

v - Date value to hash

c - The calendar to providing a timezone context for v.

addDate

public void addDate(java.sql.Date v,
                    java.util.Calendar c)

Deprecated.

adds hash of Date value to the chain.

Parameters:

v - Date value to hash.

c - The calendar to providing a timezone context for v.

addTimestamp

public void addTimestamp(java.sql.Timestamp v,
                         java.util.Calendar c)

Deprecated.

adds hash of Timestamp value to the chain.

Parameters:

v - Timestamp value to hash

c - The calendar to providing a timezone context for v.

addTimestamp

public void addTimestamp(java.util.Date v,
                         java.util.Calendar c)

Deprecated.

adds hash of Timestamp value to the chain.

Parameters:

v - Timestamp value to hash

c - The calendar to providing a timezone context for v.

addTime

public void addTime(java.sql.Time v,
                    java.util.Calendar c)

Deprecated.

adds hash of Time value to the chain.

Parameters:

v - Time value to hash

c - The calendar to providing a timezone context for v. The date component of the calendar will influence the time due to DST.

addTime

public void addTime(java.util.Date v,
                    java.util.Calendar c)

Deprecated.

adds hash of Time value to the chain.

Parameters:

v - Time value to hash

c - The calendar to providing a timezone context for v. The date component of the calendar will influence the time due to DST.

addDouble

public void addDouble(double v)

Deprecated.

adds hash of double value to the chain.

Parameters:

v - double value to hash

addDoubleNull

public void addDoubleNull()

Deprecated.

adds hash of double null value to the chain.

addNumeric

public void addNumeric(java.math.BigDecimal src,
                       int typemod)

Deprecated.

adds hash of numeric value to the chain

Parameters:

src - The numeric value to add to hash.

typemod - The precision and scale of the numeric.

Throws:

java.lang.IllegalArgumentException - if src is too large to fit in a numeric.

getHash

public long getHash()

Deprecated.

returns the current hash value

Returns:

long value of hash

getNodeFor

public static java.lang.String getNodeFor(java.sql.Connection conn,
                                          java.lang.String schema,
                                          java.lang.String proj,
                                          long hashValue)
                                   throws java.sql.SQLException

Deprecated.

Returns the name of the node that will be responsible for the provided value in the hash space for a given projection. This method uses the provided Connection to call the get_projection_segments() SQL meta-function. It then relies on getNodeFor(String, long) to determine which node to use. In situations where you need to compute many hashes for the same projection, it is would be much more efficient to call get_projection_segments() once via JDBC and then pass that output to getNodeFor(String, long) directly. Caution: There is no guarantee that connecting to the node returned by this method will guarantee reduced intra-node traffic for a query or load based on the input hash value. While that is often true, the Vertica Optmizer may not always construct such a plan.

Additionally, no check is done to ensure that the input hash value was created in a manner that is consistent with the segmentation of the provided projection. This means, for example, if the projection is segmented by an INTEGER column and the caller provides a hashed DOUBLE PRECISION value, the answer may not be correct.

Parameters:

conn - A connection to a vertica database containing the projection

schema - The schema of the projection

proj - The name of the projection

hashValue - A hashed data value for this projection

Returns:

The name of the node that is responsible for the provided hash value

Throws:

java.sql.SQLException - If a database error occurs

java.lang.IllegalArgumentException - if the projection provided is not segmented by HASH(...) ALL NODES

getNodeFor

public static java.lang.String getNodeFor(java.lang.String getProjSegmentsOutput,
                                          long hashValue)

Deprecated.

Given a projection's get_projection_segments() output, this method will return the node that is responsible for the provided hashValue. The get_projection_segments() SQL meta-function returns a list of the segment ranges each node is responsible for for a given projection. This method parses the output of that function and maps the provided hashValue to the range to determine a node name. Caution: There is no guarantee that connecting to the node returned by this method will guarantee reduced intra-node traffic for a query or load based on the input hash value. While that is often true, the Vertica Optmizer may not always construct such a plan.

Additionally, no check is done to ensure that the input hash value was created in a manner that is consistent with the segmentation of the provided projection. This means, for example, if the projection is segmented by an INTEGER column and the caller provides a hashed DOUBLE PRECISION value, the answer may not be correct.

Parameters:

getProjSegmentsOutput - -- a String containing the return value of the get_projection_segments() SQL meta-function for a particular projection.

hashValue - -- a hashed data value for the projection.

Returns:

string identifying node.

Throws:

java.lang.IllegalArgumentException - if getProjSegmentsOutput is malformed in any way, either due to bad input or due to not using a properly segmented projection.