All Implemented Interfaces:
Externalizable, Serializable, Comparable, Formatable, Storable, TypedFormat, Conglomerate, DataValueDescriptor, Orderable
Direct Known Subclasses:
B2I

public abstract class BTree extends GenericConglomerate
A b-tree object corresponds to an instance of a b-tree conglomerate. It contains the static information about a conglomerate which is built at create conglomerate time.

This generic implementation is expected to be extended by the concreate implementations.

The fields are set when the conglomerate is created and never changed thereafter. When alter table is supported then it will change under the control of a table level lock.

They have package scope because they're read by the scans and controllers.

A table of all conglomerates in the system is maintained by the accessmanager. A cache of conglomerates is maintained in the accessmanager, and references to the read only objects are handed out. A copy of the Conglomerate object is kept in the control row of the root page, so that during logical undo this information can be read without needing to access the possibly corrupt table maintained by the access manager.

See Also:
  • Field Details

    • ROOTPAGEID

      public static final long ROOTPAGEID
      The page number of the root page is always at the fixed page number: ROOTPAGEID. This means that given an open container, during logical undo one can always find the root page and look up the conglomerate information.
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    • PROPERTY_MAX_ROWS_PER_PAGE_PARAMETER

      public static final String PROPERTY_MAX_ROWS_PER_PAGE_PARAMETER
      Property name for the maximum number of rows to place in a btree page (leaf or branch). Equal to 'derby.access.btreeMaxRowPerPage'. Used by tests and debugging to exactly control split points, and to make it easier to test tall trees without needing lots of data.
    • PROPERTY_ALLOWDUPLICATES

      public static final String PROPERTY_ALLOWDUPLICATES
      See Also:
    • PROPERTY_NKEYFIELDS

      public static final String PROPERTY_NKEYFIELDS
      See Also:
    • PROPERTY_NUNIQUECOLUMNS

      public static final String PROPERTY_NUNIQUECOLUMNS
      See Also:
    • PROPERTY_UNIQUE_WITH_DUPLICATE_NULLS

      public static final String PROPERTY_UNIQUE_WITH_DUPLICATE_NULLS
      See Also:
    • id

      protected ContainerKey id
      The id of the container in which this b-tree is stored.
    • nKeyFields

      protected int nKeyFields
      The number of key fields.
    • nUniqueColumns

      int nUniqueColumns
      The number of uniqueness columns. These are the columns that are considered for the purpose of detecting duplicate keys and rows.
    • allowDuplicates

      boolean allowDuplicates
      Whether the index allows duplicates or not.
    • uniqueWithDuplicateNulls

      boolean uniqueWithDuplicateNulls
      Attribute to indicate the index allows duplicate only in case of keys with no part null. This attribute has no effect if unique is true. If unique is false and isUniqueWithDuplicateNulls is set to true the index will allow duplicates of any key with at least one column null, but for non null keys will act like a unique index.
    • maxRowsPerPage

      static int maxRowsPerPage
      Maximum rows per page to place on a btree leaf or nonleaf page. Used by testing to finely control split points. Only changed for debugging purposes. RESOLVE (mikem) - this should not be static. Need to design a way in debugging mode to get btree created with a persistent "maxRowsPerPage". This hack makes all btrees get created with the "last" maxRowsPerPage value set.
    • conglom_format_id

      protected int conglom_format_id
      Format id of the conglomerate.
    • format_ids

      protected int[] format_ids
      The array of format id's, one for each column in the template.
    • ascDescInfo

      protected boolean[] ascDescInfo
    • collation_ids

      protected int[] collation_ids
      The array of collation id's for each column in the template.
    • hasCollatedTypes

      protected boolean hasCollatedTypes
      Tells if there is at least one column in the conglomerate whose collation isn't StringDataValue.COLLATION_TYPE_UCS_BASIC.
  • Constructor Details

    • BTree

      public BTree()
  • Method Details

    • getBtreeLockingPolicy

      protected abstract BTreeLockingPolicy getBtreeLockingPolicy(Transaction rawtran, int lock_level, int mode, int isolation_level, ConglomerateController base_cc, OpenBTree open_btree) throws StandardException
      Create a new btree locking policy from scratch.
      Throws:
      StandardException - Standard exception policy.
    • lockTable

      public abstract ConglomerateController lockTable(TransactionManager xact_manager, int open_mode, int lock_level, int isolation_level) throws StandardException
      Lock the base table.

      Assumes that segment of the base container is the same as the segment of the btree segment.

      RESOLVE - we really want to get the lock without opening the container. raw store will be providing this.

      Parameters:
      xact_manager - Transaction to associate the lock with.
      Throws:
      StandardException - Standard exception policy.
    • createBranchTemplate

      final DataValueDescriptor[] createBranchTemplate(Transaction rawtran, DataValueDescriptor page_ptr) throws StandardException
      Create a branch row template for this conglomerate.

      Reads the format id's of each of the columns and manufactures object of the given type for each. It then uses these "empty" objects to create a template row. The object passed in is then added to the last column of the row.

      Returns:
      The new template.
      Throws:
      StandardException - Standard exception policy.
    • createTemplate

      public final DataValueDescriptor[] createTemplate(Transaction rawtran) throws StandardException
      Create a template for this conglomerate.

      Reads the format id's of each of the columns and manufactures object of the given type for each. It then uses these "empty" objects to create a template row.

      This method is public so that B2IUndo() can call it.

      Returns:
      The new template.
      Throws:
      StandardException - Standard exception policy.
    • isUnique

      public final boolean isUnique()
      Is this a "unique" index?
    • setUniqueWithDuplicateNulls

      public void setUniqueWithDuplicateNulls(boolean uniqueWithDuplicateNulls)
      Set if the index is unique only for non null keys
      Parameters:
      uniqueWithDuplicateNulls - true if the index will be unique only for non null keys
    • isUniqueWithDuplicateNulls

      public boolean isUniqueWithDuplicateNulls()
      Returns if the index type is uniqueWithDuplicateNulls.
      Returns:
      is index type is uniqueWithDuplicateNulls
    • addColumn

      public void addColumn(TransactionManager xact_manager, int column_id, Storable template_column, int collation_id) throws StandardException
      Add a column to the conglomerate.

      Currently B2I does not support this operation. input template column.

      Parameters:
      xact_manager - Transaction to associate the lock with.
      column_id - The column number to add this column at.
      template_column - An instance of the column to be added to table.
      collation_id - Collation id of the added column.
      Throws:
      StandardException - Standard exception policy.
    • getId

      public final ContainerKey getId()
      Get the id of the container of the conglomerate.

      Will have to change when a conglomerate could have more than one container. The ContainerKey is a combination of the container id and segment id.

      Returns:
      The ContainerKey.
    • create

      public void create(Transaction rawtran, int segmentId, long input_containerid, DataValueDescriptor[] template, Properties properties, int conglom_format_id, int tmpFlag) throws StandardException
      Do the generic part of creating a b-tree conglomerate. This method is called from the concrete subclass (which may also read some properties).

      This method processes all properties which are generic to all BTree's. It creates the container for the btree.

      The following properties are generic to a b-tree conglomerate. :

      • "allowDuplicates" (boolean). If set to true the table will allow rows which are duplicate in key column's 0 through (nUniqueColumns - 1). Currently only supports "false". This property is optional, defaults to false.
      • "nKeyFields" (integer) Columns 0 through (nKeyFields - 1) will be included in key of the conglomerate. This implementation requires that "nKeyFields" must be the same as the number of fields in the conglomerate, including the rowLocationColumn. Other implementations may relax this restriction to allow non-key fields in the index. This property is required.
      • "nUniqueColumns" (integer) Columns 0 through "nUniqueColumns" will be used to check for uniqueness. So for a standard SQL non-unique index implementation set "nUniqueColumns" to the same value as "nKeyFields"; and for a unique index set "nUniqueColumns" to "nKeyFields" - 1 (ie. don't include the rowLocationColumn in the uniqueness check). This property is required.
      • "maintainParentLinks" (boolean) Whether the b-tree pages maintain the page number of their parent. Only used for consistency checking. It takes a certain amount more effort to maintain these links, but they're really handy for ensuring that the index is consistent. This property is optional, defaults to true.
      Throws:
      StandardException - Thrown by underlying raw store, or thrown by this routine on an invalid containerid.
    • drop

      public abstract void drop(TransactionManager xact_manager) throws StandardException
      Drop this btree. This must be done by a concrete implementation.
      Throws:
      StandardException - Standard exception policy.
      See Also:
    • load

      public abstract long load(TransactionManager xact_manager, boolean createConglom, RowLocationRetRowSource rowSource) throws StandardException
      Load a b-tree. This must be done by a concrete implementation.
      Parameters:
      xact_manager - The TransactionController under which this operation takes place.
      createConglom - If true, the conglomerate is being created in the same operation as the openAndLoadConglomerate. The enables further optimization as recovery does not require page allocation to be logged.
      rowSource - Where the rows come from.
      Returns:
      The number of rows loaded.
      Throws:
      StandardException - Standard exception policy.
      See Also:
    • getContainerid

      public long getContainerid()
      Description copied from interface: Conglomerate
      Get the containerid of conglomerate.

      Will have to change when a conglomerate could have more than one containerid.

      Returns:
      The containerid.
    • getDynamicCompiledConglomInfo

      public DynamicCompiledOpenConglomInfo getDynamicCompiledConglomInfo() throws StandardException
      Return dynamic information about the conglomerate to be dynamically reused in repeated execution of a statement.

      The dynamic info is a set of variables to be used in a given ScanController or ConglomerateController. It can only be used in one controller at a time. It is up to the caller to insure the correct thread access to this info. The type of info in this is a scratch template for btree traversal, other scratch variables for qualifier evaluation, ...

      Returns:
      The dynamic information.
      Throws:
      StandardException - Standard exception policy.
    • isTemporary

      public boolean isTemporary()
      Is this conglomerate temporary?

      Returns:
      whether conglomerate is temporary or not.
    • open

      public abstract ConglomerateController open(TransactionManager xact_manager, Transaction rawtran, boolean hold, int open_mode, int lock_level, LockingPolicy locking_policy, StaticCompiledOpenConglomInfo static_info, DynamicCompiledOpenConglomInfo dynamic_info) throws StandardException
      Open a b-tree controller. This must be done by a concrete implementation.
      Parameters:
      xact_manager - The access xact to associate all ops on cc with.
      rawtran - The raw store xact to associate all ops on cc with.
      open_mode - A bit mask of TransactionController.MODE_* bits, indicating info about the open.
      lock_level - Either TransactionController.MODE_TABLE or TransactionController.MODE_RECORD, as passed into the openConglomerate() call.
      locking_policy - The LockingPolicy to use to open the conglomerate.
      Returns:
      The open ConglomerateController.
      Throws:
      StandardException - Standard exception policy.
      See Also:
    • isNull

      public boolean isNull()
      Return whether the value is null or not. The containerid being zero is what determines nullness; subclasses are not expected to override this method.
      Returns:
      true if the value is null and false otherwise.
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    • restoreToNull

      public void restoreToNull()
      Restore the in-memory representation to the null value. The containerid being zero is what determines nullness; subclasses are not expected to override this method.
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    • readExternal

      public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException
      Restore the in-memory representation from the stream.
      Throws:
      ClassNotFoundException - Thrown if the stored representation is serialized and a class named in the stream could not be found.
      IOException - thrown by readObject()
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    • writeExternal

      public void writeExternal(ObjectOutput out) throws IOException
      Store the stored representation of the column value in the stream. It might be easier to simply store the properties - which would certainly make upgrading easier.
      Throws:
      IOException - thrown by writeObject()
    • toString

      public String toString()
      Public toString() Method:
      Overrides:
      toString in class Object