Class HeapRowLocation

  • All Implemented Interfaces:
    java.io.Externalizable, java.io.Serializable, java.lang.Comparable, Formatable, Storable, TypedFormat, DataValueDescriptor, Orderable, RefDataValue, RowLocation

    public class HeapRowLocation
    extends DataType
    implements RowLocation, RefDataValue
    A heap row location represents the location of a row in the heap.

    It is implementad as a wrapper around a raw store record handle.

    See Also:
    Serialized Form
    Format IDACCESS_HEAP_ROW_LOCATION_V1_ID
    Purpose
    Object used to store the location of a row within a Heap table. One of these is stored in every row of a btree secondary index built on a heap base table.
    Upgrade
    The type of the btree determines the type of rowlocation stored. In current btree implementations only one type of rowlocation can be stored per tree, and it's type is stored in the format id array stored in the Conglomerate object.
    Disk Layoutpage number(CompressedNumber.writeLong()) record id(CompressedNumber.writeInt())
    • Field Detail

      • pageno

        private long pageno
        The HeapRowLocation simply maintains a raw store record handle.
      • recid

        private int recid
      • BASE_MEMORY_USAGE

        private static final int BASE_MEMORY_USAGE
      • RECORD_HANDLE_MEMORY_USAGE

        private static final int RECORD_HANDLE_MEMORY_USAGE
    • Constructor Detail

      • HeapRowLocation

        public HeapRowLocation()
    • Method Detail

      • estimateMemoryUsage

        public int estimateMemoryUsage()
        Description copied from interface: DataValueDescriptor
        Estimate the memory usage in bytes of the data value and the overhead of the class.
        Specified by:
        estimateMemoryUsage in interface DataValueDescriptor
        Returns:
        the estimated memory usage
      • setValueFromResultSet

        public void setValueFromResultSet​(java.sql.ResultSet resultSet,
                                          int colNumber,
                                          boolean isNullable)
        Description copied from interface: DataValueDescriptor
        Set the value based on the value for the specified DataValueDescriptor from the specified ResultSet.
        Specified by:
        setValueFromResultSet in interface DataValueDescriptor
        Parameters:
        resultSet - The specified ResultSet.
        colNumber - The 1-based column # into the resultSet.
        isNullable - Whether or not the column is nullable (No need to call wasNull() if not)
      • getObject

        public java.lang.Object getObject()
        Description copied from class: DataType
        Gets the value in the data value descriptor as a int. Throws an exception if the data value is not receivable as a int.
        Specified by:
        getObject in interface DataValueDescriptor
        Overrides:
        getObject in class DataType
        Returns:
        The data value as a int.
      • cloneValue

        public DataValueDescriptor cloneValue​(boolean forceMaterialization)
        Description copied from interface: DataValueDescriptor
        Clone this DataValueDescriptor. Results in a new object that has the same value as this but can be modified independently.

        Even though the objects can be modified independently regardless of the value of forceMaterialization, both the clone and the original may be dependent on the store state if forceMaterialization is set to false. An example is if you need to access the value you just read using cloneValue after the current transaction has ended, or after the source result set has been closed.

        Specified by:
        cloneValue in interface DataValueDescriptor
        Parameters:
        forceMaterialization - any streams representing the data value will be materialized if true, the data value will be kept as a stream if possible if false
        Returns:
        A clone of the DataValueDescriptor with the same initial value as this.
      • getLength

        public int getLength()
        Description copied from interface: DataValueDescriptor
        Gets the length of the data value. The meaning of this is implementation-dependent. For string types, it is the number of characters in the string. For numeric types, it is the number of bytes used to store the number. This is the actual length of this value, not the length of the type it was defined as. For example, a VARCHAR value may be shorter than the declared VARCHAR (maximum) length.
        Specified by:
        getLength in interface DataValueDescriptor
        Returns:
        The length of the data value
      • getString

        public java.lang.String getString()
        Description copied from interface: DataValueDescriptor
        Gets the value in the data value descriptor as a String. Throws an exception if the data value is not a string.
        Specified by:
        getString in interface DataValueDescriptor
        Returns:
        The data value as a String.
      • compare

        public boolean compare​(int op,
                               DataValueDescriptor other,
                               boolean orderedNulls,
                               boolean unknownRV)
        Description copied from interface: DataValueDescriptor
        Compare this Orderable with a given Orderable for the purpose of qualification and sorting. The caller gets to determine how nulls should be treated - they can either be ordered values or unknown values.
        Specified by:
        compare in interface DataValueDescriptor
        Overrides:
        compare in class DataType
        Parameters:
        op - Orderable.ORDER_OP_EQUALS means do an = comparison. Orderable.ORDER_OP_LESSTHAN means compare this < other. Orderable.ORDER_OP_LESSOREQUALS means compare this <= other.
        other - The DataValueDescriptor to compare this one to.
        orderedNulls - True means to treat nulls as ordered values, that is, treat SQL null as equal to null, and less than all other values. False means to treat nulls as unknown values, that is, the result of any comparison with a null is the UNKNOWN truth value.
        unknownRV - The return value to use if the result of the comparison is the UNKNOWN truth value. In other words, if orderedNulls is false, and a null is involved in the comparison, return unknownRV. This parameter is not used orderedNulls is true.
        Returns:
        true if the comparison is true (duh!)
      • compare

        public int compare​(DataValueDescriptor other)
        Description copied from interface: DataValueDescriptor
        Compare this Orderable with a given Orderable for the purpose of index positioning. This method treats nulls as ordered values - that is, it treats SQL null as equal to null and greater than all other values.
        Specified by:
        compare in interface DataValueDescriptor
        Parameters:
        other - The Orderable to compare this one to.
        Returns:
        <0 - this Orderable is less than other. 0 - this Orderable equals other. >0 - this Orderable is greater than other. The code should not explicitly look for -1, or 1.
      • setValue

        public void setValue​(RowLocation rowLocation)
        Description copied from interface: RefDataValue
        Set the value of this RefDataValue.
        Specified by:
        setValue in interface RefDataValue
        Parameters:
        rowLocation - Contains the boolean value to set this RefDataValue to. Null means set this RefDataValue to null.
      • isNull

        public boolean isNull()
        Description copied from interface: Storable
        Return whether the value is null or not.
        Specified by:
        isNull in interface Storable
        Returns:
        true if the value is null and false otherwise.
      • writeExternal

        public void writeExternal​(java.io.ObjectOutput out)
                           throws java.io.IOException
        Specified by:
        writeExternal in interface java.io.Externalizable
        Throws:
        java.io.IOException
      • readExternal

        public void readExternal​(java.io.ObjectInput in)
                          throws java.io.IOException,
                                 java.lang.ClassNotFoundException
        Specified by:
        readExternal in interface java.io.Externalizable
        Throws:
        java.lang.ClassNotFoundException - A class needed to read the stored form of this object could not be found.
        java.io.IOException
        See Also:
        Externalizable.readExternal(java.io.ObjectInput)
      • readExternalFromArray

        public void readExternalFromArray​(ArrayInputStream in)
                                   throws java.io.IOException,
                                          java.lang.ClassNotFoundException
        Description copied from class: DataType
        Read the DataValueDescriptor from the stream. The default implementation calls readExternal(), which accesses the ArrayInputStream as a generic stream. If sub-classes can implement it more efficiently by accessing the array, they should override this method.
        Specified by:
        readExternalFromArray in interface DataValueDescriptor
        Overrides:
        readExternalFromArray in class DataType
        Parameters:
        in - The array stream positioned at the beginning of the byte stream to read from.
        Throws:
        java.io.IOException - Usual error is if you try to read past limit on the stream.
        java.lang.ClassNotFoundException - If a necessary class can not be found while reading the object from the stream.
        See Also:
        DataValueDescriptor.readExternalFromArray(org.apache.derby.iapi.services.io.ArrayInputStream), Externalizable.readExternal(java.io.ObjectInput)
      • restoreToNull

        public void restoreToNull()
        Description copied from interface: Storable
        Restore this object to its (SQL)null value.
        Specified by:
        restoreToNull in interface Storable
      • setFrom

        protected void setFrom​(DataValueDescriptor theValue)
        Description copied from class: DataType
        Set the value of this DataValueDescriptor based on the value of the specified DataValueDescriptor.
        Overrides:
        setFrom in class DataType
        Parameters:
        theValue - The DataValueDescriptor that holds the value to which we want to set this DataValueDescriptor's value.
      • equals

        public boolean equals​(java.lang.Object ref)
        Implement value equality.
        MT - Thread safe
        Overrides:
        equals in class DataType
      • hashCode

        public int hashCode()
        Return a hashcode based on value.
        MT - thread safe
        Overrides:
        hashCode in class java.lang.Object
      • toString

        public java.lang.String toString()
        Overrides:
        toString in class java.lang.Object