Package org.postgresql

# Interface PGConnection

All Known Subinterfaces:
  `BaseConnection`

All Known Implementing Classes:
  `PgConnection`

public interface PGConnection
This interface defines the public PostgreSQL extensions to java.sql.Connection. All Connections returned by the PostgreSQL driver implement PGConnection.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `void`
  `addDataType(String type, Class<? extends PGobject> klass)`
  This allows client code to add a handler for one of org.postgresql's more unique data types.
  `void`
  `addDataType(String type, String className)`
  Deprecated.
  As of 8.0, replaced by `addDataType(String, Class)`.
  `default void`
  `alterUserPassword(String user, char[] newPassword, @Nullable String encryptionType)`
  Change a user's password to the specified new password.
  `void`
  `cancelQuery()`
  Sends a query cancellation for this connection.
  `Array`
  `createArrayOf(String typeName, @Nullable Object elements)`
  Creates an `Array` wrapping elements.
  `String`
  `escapeIdentifier(String identifier)`
  Return the given string suitably quoted to be used as an identifier in an SQL statement string.
  `String`
  `escapeLiteral(String literal)`
  Return the given string suitably quoted to be used as a string literal in an SQL statement string.
  `boolean`
  `getAdaptiveFetch()`
  Get state of adaptive fetch for connection.
  `AutoSave`
  `getAutosave()`
  Connection configuration regarding automatic per-query savepoints.
  `int`
  `getBackendPID()`
  Return the process ID (PID) of the backend server process handling this connection.
  `CopyManager`
  `getCopyAPI()`
  This returns the COPY API for the current connection.
  `int`
  `getDefaultFetchSize()`
  Get the default fetch size for statements created from this connection.
  `Fastpath`
  `getFastpathAPI()`
  This returns the Fastpath API for the current connection.
  `LargeObjectManager`
  `getLargeObjectAPI()`
  This returns the LargeObject API for the current connection.
  `PGNotification[]`
  `getNotifications()`
  This method returns any notifications that have been received since the last call to this method.
  `PGNotification[]`
  `getNotifications(int timeoutMillis)`
  This method returns any notifications that have been received since the last call to this method.
  `@Nullable String`
  `getParameterStatus(String parameterName)`
  Shorthand for getParameterStatuses().get(...) .
  `Map<String,String>`
  `getParameterStatuses()`
  Returns the current values of all parameters reported by the server.
  `PreferQueryMode`
  `getPreferQueryMode()`
  Returns the query mode for this connection.
  `int`
  `getPrepareThreshold()`
  Get the default server-side prepare reuse threshold for statements created from this connection.
  `PGReplicationConnection`
  `getReplicationAPI()`
  `void`
  `setAdaptiveFetch(boolean adaptiveFetch)`
  Turn on/off adaptive fetch for connection.
  `void`
  `setAutosave(AutoSave autoSave)`
  Configures if connection should use automatic savepoints.
  `void`
  `setDefaultFetchSize(int fetchSize)`
  Set the default fetch size for statements created from this connection.
  `void`
  `setPrepareThreshold(int threshold)`
  Set the default statement reuse threshold before enabling server-side prepare.

- ## Method Details

  - ### createArrayOf

    Array createArrayOf(String typeName, @Nullable Object elements) throws SQLException
    Creates an `Array` wrapping elements. This is similar to `Connection.createArrayOf(String, Object[])`, but also provides support for primitive arrays.
    Parameters:
      `typeName` - The SQL name of the type to map the elements to. Must not be `null`.
      `elements` - The array of objects to map. A `null` value will result in an `Array` representing `null`.
    Returns:
      An `Array` wrapping elements.
    Throws:
      `SQLException` - If for some reason the array cannot be created.
    See Also:
      - `Connection.createArrayOf(String, Object[])`

  - ### getNotifications

    PGNotification[] getNotifications() throws SQLException
    This method returns any notifications that have been received since the last call to this method. Returns an empty array if there have been no notifications.
    Returns:
      notifications that have been received
    Throws:
      `SQLException` - if something wrong happens
    Since:
      7.3

  - ### getNotifications

    PGNotification[] getNotifications(int timeoutMillis) throws SQLException
    This method returns any notifications that have been received since the last call to this method. Returns an empty array if there have been no notifications. A timeout can be specified so the driver waits for notifications.
    Parameters:
      `timeoutMillis` - when 0, blocks forever. when > 0, blocks up to the specified number of millis or until at least one notification has been received. If more than one notification is about to be received, these will be returned in one batch.
    Returns:
      notifications that have been received
    Throws:
      `SQLException` - if something wrong happens
    Since:
      43

  - ### getCopyAPI

    CopyManager getCopyAPI() throws SQLException
    This returns the COPY API for the current connection.
    Returns:
      COPY API for the current connection
    Throws:
      `SQLException` - if something wrong happens
    Since:
      8.4

  - ### getLargeObjectAPI

    LargeObjectManager getLargeObjectAPI() throws SQLException
    This returns the LargeObject API for the current connection.
    Returns:
      LargeObject API for the current connection
    Throws:
      `SQLException` - if something wrong happens
    Since:
      7.3

  - ### getFastpathAPI

    Fastpath getFastpathAPI() throws SQLException
    This returns the Fastpath API for the current connection.

    Note: This API is somewhat obsolete, as one may achieve similar performance and greater functionality by setting up a prepared statement to define the function call. Then, executing the statement with binary transmission of parameters and results substitutes for a fast-path function call.

    Returns:
      Fastpath API for the current connection
    Throws:
      `SQLException` - if something wrong happens
    Since:
      7.3

  - ### addDataType

    @Deprecated void addDataType(String type, String className)
    Deprecated.
    As of 8.0, replaced by `addDataType(String, Class)`. This deprecated method does not work correctly for registering classes that cannot be directly loaded by the JDBC driver's classloader.
    This allows client code to add a handler for one of org.postgresql's more unique data types. It is approximately equivalent to `addDataType(type, Class.forName(name))`.
    Parameters:
      `type` - JDBC type name
      `className` - class name
    Throws:
      `RuntimeException` - if the type cannot be registered (class not found, etc).

  - ### addDataType

    void addDataType(String type, Class<? extends PGobject> klass) throws SQLException
    This allows client code to add a handler for one of org.postgresql's more unique data types.

    NOTE: This is not part of JDBC, but an extension.

    The best way to use this is as follows:

         ...
         ((org.postgresql.PGConnection)myconn).addDataType("mytype", my.class.name.class);
         ...

    where myconn is an open Connection to org.postgresql.

    The handling class must extend org.postgresql.util.PGobject

    Parameters:
      `type` - the PostgreSQL type to register
      `klass` - the class implementing the Java representation of the type; this class must implement `PGobject`).
    Throws:
      `SQLException` - if `klass` does not implement `PGobject`).
    Since:
      8.0
    See Also:
      - `PGobject`

  - ### setPrepareThreshold

    void setPrepareThreshold(int threshold)
    Set the default statement reuse threshold before enabling server-side prepare. See `PGStatement.setPrepareThreshold(int)` for details.
    Parameters:
      `threshold` - the new threshold
    Since:
      build 302

  - ### getPrepareThreshold

    int getPrepareThreshold()
    Get the default server-side prepare reuse threshold for statements created from this connection.
    Returns:
      the current threshold
    Since:
      build 302

  - ### setDefaultFetchSize

    void setDefaultFetchSize(int fetchSize) throws SQLException
    Set the default fetch size for statements created from this connection.
    Parameters:
      `fetchSize` - new default fetch size
    Throws:
      `SQLException` - if specified negative `fetchSize` parameter
    See Also:
      - `Statement.setFetchSize(int)`

  - ### getDefaultFetchSize

    int getDefaultFetchSize()
    Get the default fetch size for statements created from this connection.
    Returns:
      current state for default fetch size
    See Also:
      - `PGProperty.DEFAULT_ROW_FETCH_SIZE`
      - `Statement.getFetchSize()`

  - ### getBackendPID

    int getBackendPID()
    Return the process ID (PID) of the backend server process handling this connection.
    Returns:
      PID of backend server process.

  - ### cancelQuery

    void cancelQuery() throws SQLException
    Sends a query cancellation for this connection.
    Throws:
      `SQLException` - if there are problems cancelling the query

  - ### escapeIdentifier

    String escapeIdentifier(String identifier) throws SQLException
    Return the given string suitably quoted to be used as an identifier in an SQL statement string. Quotes are added only if necessary (i.e., if the string contains non-identifier characters or would be case-folded). Embedded quotes are properly doubled.
    Parameters:
      `identifier` - input identifier
    Returns:
      the escaped identifier
    Throws:
      `SQLException` - if something goes wrong

  - ### escapeLiteral

    String escapeLiteral(String literal) throws SQLException
    Return the given string suitably quoted to be used as a string literal in an SQL statement string. Embedded single-quotes and backslashes are properly doubled. Note that quote_literal returns null on null input.
    Parameters:
      `literal` - input literal
    Returns:
      the quoted literal
    Throws:
      `SQLException` - if something goes wrong

  - ### getPreferQueryMode

    PreferQueryMode getPreferQueryMode()
    Returns the query mode for this connection.

    When running in simple query mode, certain features are not available: callable statements, partial result set fetch, bytea type, etc.

    The list of supported features is subject to change.

    Returns:
      the preferred query mode
    See Also:
      - `PreferQueryMode`

  - ### getAutosave

    AutoSave getAutosave()
    Connection configuration regarding automatic per-query savepoints.
    Returns:
      connection configuration regarding automatic per-query savepoints
    See Also:
      - `PGProperty.AUTOSAVE`

  - ### setAutosave

    void setAutosave(AutoSave autoSave)
    Configures if connection should use automatic savepoints.
    Parameters:
      `autoSave` - connection configuration regarding automatic per-query savepoints
    See Also:
      - `PGProperty.AUTOSAVE`

  - ### getReplicationAPI

    PGReplicationConnection getReplicationAPI()
    Returns:
      replication API for the current connection

  - ### alterUserPassword

    default void alterUserPassword(String user, char[] newPassword, @Nullable String encryptionType) throws SQLException
    Change a user's password to the specified new password.

    If the specific encryption type is not specified, this method defaults to querying the database server for the server's default password_encryption. This method does not send the new password in plain text to the server. Instead, it encrypts the password locally and sends the encoded hash so that the plain text password is never sent on the wire.

    Acceptable values for encryptionType are null, "md5", or "scram-sha-256". Users should avoid "md5" unless they are explicitly targeting an older server that does not support the more secure SCRAM.

    Parameters:
      `user` - The username of the database user
      `newPassword` - The new password for the database user. The implementation will zero out the array after use
      `encryptionType` - The type of password encryption to use or null if the database server default should be used.
    Throws:
      `SQLException` - If the password could not be altered

  - ### getParameterStatuses

    Map<String,String> getParameterStatuses()
    Returns the current values of all parameters reported by the server.

    PostgreSQL reports values for a subset of parameters (GUCs) to the client at connect-time, then sends update messages whenever the values change during a session. PgJDBC records the latest values and exposes it to client applications via `getParameterStatuses()`.

    PgJDBC exposes individual accessors for some of these parameters as listed below. They are more backwards-compatible and should be preferred where possible.

    Not all parameters are reported, only those marked `GUC_REPORT` in the source code. The `pg_settings` view does not expose information about which parameters are reportable. PgJDBC's map will only contain the parameters the server reports values for, so you cannot use this method as a substitute for running a `SHOW paramname;` or `SELECT current_setting('paramname');` query for arbitrary parameters.

    Parameter names are case-insensitive and case-preserving in this map, like in PostgreSQL itself. So `DateStyle` and `datestyle` are the same key.

    As of PostgreSQL 11 the reportable parameter list, and related PgJDBC interfaces or assessors, are:

    - `application_name` - `Connection.getClientInfo()`, `Connection.setClientInfo(java.util.Properties)` and `ApplicationName` connection property.
    - `client_encoding` - PgJDBC always sets this to `UTF8`. See `allowEncodingChanges` connection property.
    - `DateStyle` - PgJDBC requires this to always be set to `ISO`
    - `standard_conforming_strings` - indirectly via `escapeLiteral(String)`
    - `TimeZone` - set from JDK timezone see `TimeZone.getDefault()` and `TimeZone.setDefault(TimeZone)`
    - `integer_datetimes`
    - `IntervalStyle`
    - `server_encoding`
    - `server_version`
    - `is_superuser`
    - `session_authorization`

    Note that some PgJDBC operations will change server parameters automatically.

    Returns:
      unmodifiable map of case-insensitive parameter names to parameter values
    Since:
      42.2.6

  - ### getParameterStatus

    @Nullable String getParameterStatus(String parameterName)
    Shorthand for getParameterStatuses().get(...) .
    Parameters:
      `parameterName` - case-insensitive parameter name
    Returns:
      parameter value if defined, or null if no parameter known
    Since:
      42.2.6
    See Also:
      - `getParameterStatuses()`

  - ### setAdaptiveFetch

    void setAdaptiveFetch(boolean adaptiveFetch)
    Turn on/off adaptive fetch for connection. Existing statements and resultSets won't be affected by change here.
    Parameters:
      `adaptiveFetch` - desired state of adaptive fetch.

  - ### getAdaptiveFetch

    boolean getAdaptiveFetch()
    Get state of adaptive fetch for connection.
    Returns:
      state of adaptive fetch (turned on or off)