Package org.postgresql.fastpath

# Class Fastpath

java.lang.Object
org.postgresql.fastpath.Fastpath

public class Fastpath extends Object
This class implements the Fastpath api.

This is a means of executing functions embedded in the backend from within a java application.

It is based around the file src/interfaces/libpq/fe-exec.c

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `Fastpath(BaseConnection conn)`
  Initialises the fastpath system.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `void`
  `addFunction(String name, int fnid)`
  This adds a function to our lookup table.
  `void`
  `addFunctions(ResultSet rs)`
  This takes a ResultSet containing two columns.
  `static FastpathArg`
  `createOIDArg(long oid)`
  Creates a FastpathArg with an oid parameter.
  `@Nullable Object`
  `fastpath(int fnId, boolean resultType, FastpathArg[] args)`
  Deprecated.
  please use `fastpath(int, FastpathArg[])`
  `byte @Nullable []`
  `fastpath(int fnId, FastpathArg[] args)`
  Send a function call to the PostgreSQL backend.
  `@Nullable Object`
  `fastpath(String name, boolean resulttype, FastpathArg[] args)`
  Deprecated.
  Use `getData(String, FastpathArg[])` if you expect a binary result, or one of `getInteger(String, FastpathArg[])` or `getLong(String, FastpathArg[])` if you expect a numeric one
  `byte @Nullable []`
  `fastpath(String name, FastpathArg[] args)`
  Send a function call to the PostgreSQL backend by name.
  `byte @Nullable []`
  `getData(String name, FastpathArg[] args)`
  This convenience method assumes that the return value is not an Integer.
  `int`
  `getID(String name)`
  This returns the function id associated by its name.
  `int`
  `getInteger(String name, FastpathArg[] args)`
  This convenience method assumes that the return value is an integer.
  `long`
  `getLong(String name, FastpathArg[] args)`
  This convenience method assumes that the return value is a long (bigint).
  `long`
  `getOID(String name, FastpathArg[] args)`
  This convenience method assumes that the return value is an oid.

  ### Methods inherited from class java.lang.Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Constructor Details

  - ### Fastpath

    public Fastpath(BaseConnection conn)
    Initialises the fastpath system.
    Parameters:
      `conn` - BaseConnection to attach to

- ## Method Details

  - ### fastpath

    @Deprecated public @Nullable Object fastpath(int fnId, boolean resultType, FastpathArg[] args) throws SQLException
    Deprecated.
    please use `fastpath(int, FastpathArg[])`
    Send a function call to the PostgreSQL backend.
    Parameters:
      `fnId` - Function id
      `resultType` - True if the result is a numeric (Integer or Long)
      `args` - FastpathArguments to pass to fastpath
    Returns:
      null if no data, Integer if an integer result, Long if a long result, or byte[] otherwise
    Throws:
      `SQLException` - if a database-access error occurs.

  - ### fastpath

    public byte @Nullable [] fastpath(int fnId, FastpathArg[] args) throws SQLException
    Send a function call to the PostgreSQL backend.
    Parameters:
      `fnId` - Function id
      `args` - FastpathArguments to pass to fastpath
    Returns:
      null if no data, byte[] otherwise
    Throws:
      `SQLException` - if a database-access error occurs.

  - ### fastpath

    @Deprecated public @Nullable Object fastpath(String name, boolean resulttype, FastpathArg[] args) throws SQLException
    Deprecated.
    Use `getData(String, FastpathArg[])` if you expect a binary result, or one of `getInteger(String, FastpathArg[])` or `getLong(String, FastpathArg[])` if you expect a numeric one
    Parameters:
      `name` - Function name
      `resulttype` - True if the result is a numeric (Integer or Long)
      `args` - FastpathArguments to pass to fastpath
    Returns:
      null if no data, Integer if an integer result, Long if a long result, or byte[] otherwise
    Throws:
      `SQLException` - if something goes wrong
    See Also:
      - `fastpath(int, FastpathArg[])`
      - `fastpath(String, FastpathArg[])`

  - ### fastpath

    public byte @Nullable [] fastpath(String name, FastpathArg[] args) throws SQLException
    Send a function call to the PostgreSQL backend by name.

    Note: the mapping for the procedure name to function id needs to exist, usually to an earlier call to addfunction().

    This is the preferred method to call, as function id's can/may change between versions of the backend.

    For an example of how this works, refer to org.postgresql.largeobject.LargeObject

    Parameters:
      `name` - Function name
      `args` - FastpathArguments to pass to fastpath
    Returns:
      null if no data, byte[] otherwise
    Throws:
      `SQLException` - if name is unknown or if a database-access error occurs.
    See Also:
      - `LargeObject`

  - ### getInteger

    public int getInteger(String name, FastpathArg[] args) throws SQLException
    This convenience method assumes that the return value is an integer.
    Parameters:
      `name` - Function name
      `args` - Function arguments
    Returns:
      integer result
    Throws:
      `SQLException` - if a database-access error occurs or no result

  - ### getLong

    public long getLong(String name, FastpathArg[] args) throws SQLException
    This convenience method assumes that the return value is a long (bigint).
    Parameters:
      `name` - Function name
      `args` - Function arguments
    Returns:
      long result
    Throws:
      `SQLException` - if a database-access error occurs or no result

  - ### getOID

    public long getOID(String name, FastpathArg[] args) throws SQLException
    This convenience method assumes that the return value is an oid.
    Parameters:
      `name` - Function name
      `args` - Function arguments
    Returns:
      oid of the given call
    Throws:
      `SQLException` - if a database-access error occurs or no result

  - ### getData

    public byte @Nullable [] getData(String name, FastpathArg[] args) throws SQLException
    This convenience method assumes that the return value is not an Integer.
    Parameters:
      `name` - Function name
      `args` - Function arguments
    Returns:
      byte[] array containing result
    Throws:
      `SQLException` - if a database-access error occurs or no result

  - ### addFunction

    public void addFunction(String name, int fnid)
    This adds a function to our lookup table.

    User code should use the addFunctions method, which is based upon a query, rather than hard coding the oid. The oid for a function is not guaranteed to remain static, even on different servers of the same version.

    Parameters:
      `name` - Function name
      `fnid` - Function id

  - ### addFunctions

    public void addFunctions(ResultSet rs) throws SQLException
    This takes a ResultSet containing two columns. Column 1 contains the function name, Column 2 the oid.

    It reads the entire ResultSet, loading the values into the function table.

    REMEMBER to close() the resultset after calling this!!

    Implementation note about function name lookups:

    PostgreSQL stores the function id's and their corresponding names in the pg_proc table. To speed things up locally, instead of querying each function from that table when required, a HashMap is used. Also, only the function's required are entered into this table, keeping connection times as fast as possible.

    The org.postgresql.largeobject.LargeObject class performs a query upon it's startup, and passes the returned ResultSet to the addFunctions() method here.

    Once this has been done, the LargeObject api refers to the functions by name.

    Don't think that manually converting them to the oid's will work. Ok, they will for now, but they can change during development (there was some discussion about this for V7.0), so this is implemented to prevent any unwarranted headaches in the future.

    Parameters:
      `rs` - ResultSet
    Throws:
      `SQLException` - if a database-access error occurs.
    See Also:
      - `LargeObjectManager`

  - ### getID

    public int getID(String name) throws SQLException
    This returns the function id associated by its name.

    If addFunction() or addFunctions() have not been called for this name, then an SQLException is thrown.

    Parameters:
      `name` - Function name to lookup
    Returns:
      Function ID for fastpath call
    Throws:
      `SQLException` - is function is unknown.

  - ### createOIDArg

    public static FastpathArg createOIDArg(long oid)
    Creates a FastpathArg with an oid parameter. This is here instead of a constructor of FastpathArg because the constructor can't tell the difference between an long that's really int8 and a long thats an oid.
    Parameters:
      `oid` - input oid
    Returns:
      FastpathArg with an oid parameter