Package org.opends.server.backends.pluggable.spi

Interface ReadableTransaction

All Known Subinterfaces:
WriteableTransaction
public interface ReadableTransaction
Represents a readable transaction on a storage engine.

  • Method Details

    • read

      default ByteString read(TreeName treeName, ByteString key)
      Reads the record's value associated to the provided key, in the tree whose name is provided.
      Parameters:
      treeName - the tree name
      key - the record's key
      Returns:
      the record's value, or null if none exists or if the tree does not exist.

    • openCursor

      default Cursor<ByteString,ByteString> openCursor(TreeName treeName)
      Opens a non-positioned cursor on the tree whose name is provided. The cursor will then have to be positioned (e.g: by invoking SequentialCursor.next()) to be defined.
      Parameters:
      treeName - the tree name
      Returns:
      a new non-positioned cursor or an empty cursor if the tree does not exist.

    • openCursor

      default Cursor<ByteString,ByteString> openCursor(TreeName treeName, Set<Storage.ReadHint> hints)
      Opens a non-positioned cursor on the tree whose name is provided. The cursor will then have to be positioned (e.g: by invoking SequentialCursor.next()) to be defined.
      Parameters:
      treeName - the tree name
      hints - the hints to apply to the opened cursor.
      Returns:
      a new non-positioned cursor or an empty cursor if the tree does not exist.

    • getRecordCount

      default long getRecordCount(TreeName treeName)
      Returns the number of key/value pairs in the provided tree.
      Parameters:
      treeName - the tree name
      Returns:
      the number of key/value pairs in the provided tree or 0 if the tree does not exist.

    • setLookThroughLimit

      default void setLookThroughLimit(long limit)
      Sets the lookthrough limit which should be applied to this transaction. The limit restricts the maximum number of records that may be accessed during a read transaction. This method is typically called at the start of a transaction and usually only for search operations. The lookthrough limit is disabled by default. A LookThroughLimitExceededException will be thrown once the lookthrough limit has been reached.
      Parameters:
      limit - The lookthrough limit. A negative or zero value indicates that there is no limit (the default).

    • getLookThroughCounter

      default long getLookThroughCounter()
      Returns the count of records accessed during a read transaction.
      Returns:
      The number of records accessed during a read transaction, or -1 if unknown.