Examples of org.apache.derby.iapi.store.raw.Page

org.apache.derby.iapi.store.raw.Page
A Page contains an ordered set of records which are the stored form of rows. A record is a stream of bytes created from a row array. The record contains one or more fields, fields have a one to one correlation with the DataValueDescriptor's contained within a row array.
A Page represents exclusive access to a data page within a container. Exclusive access is released by calling the unlatch() method, once that occurs the caller must no longer use the Page reference.
Several of the methods in Page take a RecordHandle as an argument. RecordHandles are obtained from a Page, while holding exclusive access of Page or a from a previous exclusive access of a Page representing the same data page. All RecordHandle's used as arguments to methods (with the exception of recordExists()) must be valid for the current state of the page. If they are not valid then the method will throw an exception. A caller can ensure that a record handle is valid by:
- Obtaining the handle during this exclusive access of this page
- Checking the record still exists with the method recordExists()
- Not using a handle after a deleteAtSlot().
Several of the methods in Page take a slot number as an argument. A slot always correspond to a record, which may be deleted or undeleted.
MT - Latched - In general every method requires the page to be latched.
Latching
All page methods which are not valid for a latched page throw an exception if the page is not latched. [@exception clauses on all the methods should be updated to reflect this].
Aux Objects
The page cache will manage a client object along with the page as long as it remains in cache. This object is called the "aux object". The aux object is associated with the page with setAuxObject(), and can be retreived later with getAuxObject(). The aux object will remain valid as long as the page is latched, but callers cannot assume that an aux object will ever stick around once the page is unlatched. However, the page manager promises to call pageBeingEvicted() once before clearing the aux reference from the page. @see Object @see ContainerHandle @see RecordHandle @see AuxObject

    TransactionManager      xact_mgr,
    ContainerKey            container_key)
    throws StandardException
    {
        ContainerHandle         container   = null;
        Page                    page        = null;
        DataValueDescriptor[]   control_row = new DataValueDescriptor[1];


        try
        {
            // open container to read the Heap object out of it's control row.
            container = 
                xact_mgr.getRawStoreXact().openContainer(
                    container_key, (LockingPolicy) null, 0);


            if (container == null)
            {
                throw StandardException.newException(
                    SQLState.STORE_CONGLOMERATE_DOES_NOT_EXIST,
                    new Long(container_key.getContainerId()));
            }


            // row in slot 0 of heap page 1 which is just a single column with
            // the heap entry.
            control_row[0]       = new Heap();


            page = container.getPage(ContainerHandle.FIRST_PAGE_NUMBER);


            RecordHandle rh = 
                page.fetchFromSlot(
                   (RecordHandle) null, 0, control_row, 
                   (FetchDescriptor) null,
                   true);


            if (SanityManager.DEBUG)
            {
                SanityManager.ASSERT(rh != null);


                // for now the control row is always the first id assigned on
                // page 1.
                SanityManager.ASSERT(rh.getId() == 6);
            }
        }
        finally
        {
            if (page != null)
                page.unlatch();


            if (container != null)
                container.close();
        }

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            // get a template.


            DataValueDescriptor[] row = runtime_mem.get_row_for_export();


            // Print pages of the heap.
            Page page = container.getFirstPage();


            while (page != null)
            {
                SanityManager.DEBUG_PRINT(
                    "p_heap", ConglomerateUtil.debugPage(page, 0, false, row));


                long pageid = page.getPageNumber();
                page.unlatch();
                page = container.getNextPage(pageid);
            }
        }


        return;

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        prop.put(Page.DIAG_ROWSIZE,          "");
        prop.put(Page.DIAG_MINROWSIZE,       "");
        prop.put(Page.DIAG_MAXROWSIZE,       "");


        // scan all pages in the heap gathering summary stats in stat
        Page page = container.getFirstPage();


        while (page != null)
        {
            this.diag_page(page, prop, stat);
            pageid = page.getPageNumber();
            page.unlatch();
            page = container.getNextPage(pageid);
        }


        return(this.diag_tabulate(prop, stat));
    }

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   * @exception  StandardException  Standard exception policy.
     **/
  private RecordHandle doInsert(DataValueDescriptor[] row)
    throws StandardException
  {
    Page page = null;
        byte  insert_mode;
    
        RecordHandle rh;


        if (SanityManager.DEBUG)
        {
            Heap heap = (Heap) open_conglom.getConglomerate();
            // Make sure valid columns are in the list.  The RowUtil
            // call is too expensive to make in a released system for
            // every insert.


            int invalidColumn = 
                RowUtil.columnOutOfRange(
                    row, null, heap.format_ids.length);


            if (invalidColumn >= 0)
            {
                throw(StandardException.newException(
                        SQLState.HEAP_TEMPLATE_MISMATCH,
                        new Long(invalidColumn), 
                        new Long(heap.format_ids.length)));
            }
        }


        // Get the last page that was returned for insert or the last page
        // that was allocated.
        page = open_conglom.getContainer().getPageForInsert(0);


        if (page != null) {


            // if there are 0 rows on the page allow the insert to overflow.
            insert_mode = 
                (page.recordCount() == 0) ? 
                    Page.INSERT_OVERFLOW : Page.INSERT_DEFAULT;


            // Check to see if there is enough space on the page
            // for the row.
            rh = page.insert(row, null, insert_mode,
        AccessFactoryGlobals.HEAP_OVERFLOW_THRESHOLD);
            page.unlatch();
            page = null;


            // If we have found a page with enough space for the row,
            // insert it and release exclusive access to the page.
            if (rh != null)
            {
                return rh;


            }
        }


        // If the last inserted page is now full, or RawStore have
        // forgotten what it was, or the row cannot fit on the last
        // inserted page, try to have rawStore get a relatively unfilled
        // page.


        page = 
            open_conglom.getContainer().getPageForInsert(
                ContainerHandle.GET_PAGE_UNFILLED);


        if (page != null)
        {
            // Do the insert all over again hoping that it will fit into
            // this page, and if not, allocate a new page.


            // if there are 0 rows on the page allow the insert to overflow.
            insert_mode = 
                (page.recordCount() == 0) ? 
                    Page.INSERT_OVERFLOW : Page.INSERT_DEFAULT;
            
            rh = page.insert(row, null, insert_mode,
        AccessFactoryGlobals.HEAP_OVERFLOW_THRESHOLD);


            page.unlatch();
            page = null;


            // If we have found a page with enough space for the row,
            // insert it and release exclusive access to the page.
            if (rh != null)
            {
                return rh;
            }
        }


        page = open_conglom.getContainer().addPage();


        // At this point with long rows the raw store will guarantee
        // that any size row will fit on an empty page.


        rh = page.insert(row, null, Page.INSERT_OVERFLOW,
      AccessFactoryGlobals.HEAP_OVERFLOW_THRESHOLD);
        page.unlatch();
        page = null;


        if (SanityManager.DEBUG)
        {
            // a null will only be returned if this page is not empty

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    // out these rows if the transaction rolls back.  We are counting on
    // the allocation page rollback to obliterate these rows if the
    // transaction fails, or, in the CREAT_UNLOGGED case, the whole
    // container to be removed.


    Page page = open_conglom.getContainer().addPage();


    boolean callbackWithRowLocation = rowSource.needsRowLocation();
    RecordHandle rh;
    HeapRowLocation rowlocation;


    if (callbackWithRowLocation)
      rowlocation = new HeapRowLocation();
    else
      rowlocation = null;


        FormatableBitSet validColumns = rowSource.getValidColumns();


    try
    {
       // get the next row and its valid columns from the rowSource
      DataValueDescriptor[] row;
            while ((row = rowSource.getNextRowFromRowSource()) != null)
            {
                num_rows_loaded++;


                if (SanityManager.DEBUG)
                {
                    // Make sure valid columns are in the list.  The RowUtil
                    // call is too expensive to make in a released system for 
                    // every insert.
                    int invalidColumn = 
                        RowUtil.columnOutOfRange(
                            row, validColumns, heap.format_ids.length);


                    if (invalidColumn >= 0)
                    {
                        throw(StandardException.newException(
                                SQLState.HEAP_TEMPLATE_MISMATCH,
                                new Long(invalidColumn), 
                                new Long(heap.format_ids.length)));
                    }
                }




        // Insert it onto this page as long as it can fit more rows.
        if ((rh = page.insert(
                        row, validColumns, Page.INSERT_DEFAULT,
            AccessFactoryGlobals.HEAP_OVERFLOW_THRESHOLD)) 
                                == null)
        {
          // Insert faied, row did not fit.  Get a new page.  


          page.unlatch();
          page = null;


          page = open_conglom.getContainer().addPage();


          // RESOLVE (mikem) - no long rows yet so the following code
          // will get an exception from the raw store for a row that
          // does not fit on a page.
          //
          // Multi-thread considerations aside, the raw store will 
                    // guarantee that any size row will fit on an empty page.
          rh = page.insert(
                            row, validColumns, Page.INSERT_OVERFLOW,
              AccessFactoryGlobals.HEAP_OVERFLOW_THRESHOLD);


        }


        // Else, the row fit.  If we are expected to call back with the
        // row location, do so.  All the while keep the page latched
        // and go for the next row.
        if (callbackWithRowLocation)
        {
          rowlocation.setFrom(rh);
          rowSource.rowLocation(rowlocation);
        }
      }
      page.unlatch();
      page = null;


      // Done with the container, now we need to flush it to disk since
      // it is unlogged.
            if (!heap.isTemporary())

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    {
        ControlRow            root                      = null;
        ControlRow            control_row               = null;
        DataValueDescriptor[] logged_index_row_template = null;
        DataValueDescriptor[] template                  = null;
        Page                  ret_page                  = null;
        ContainerHandle       container                 = pageOp.getContainer();
        RecordHandle          rechandle                 = pageOp.getRecordHandle();
        boolean               ok_exit                   = false;
        int                   compare_result            = 1;
        B2I                   btree                     = null;

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    ControlRow        leftchild,
    int               level,
    ControlRow        parent)
        throws StandardException
    {
        Page      page      = open_btree.container.addPage();


        // Create a control row for the new page.
        BranchControlRow control_row =
            new BranchControlRow(
                open_btree, page, level,
                parent, false, leftchild.page.getPageNumber());


        // Insert the control row on the page.
    byte insertFlag = Page.INSERT_INITIAL;
    insertFlag |= Page.INSERT_DEFAULT;
        page.insertAtSlot(
            Page.FIRST_SLOT_NUMBER,
            control_row.getRow(),
            (FormatableBitSet) null, 
            (LogicalUndo)null,
            insertFlag, AccessFactoryGlobals.BTREE_OVERFLOW_THRESHOLD);

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            // the post commit work will just skip it.
            control_row = ControlRow.GetNoWait(open_btree, pageno);


            if (control_row != null)
            {
                Page page   = control_row.page;


                // The number records that can be reclaimed is:
                // total recs - control row - recs_not_deleted
                int num_possible_commit_delete = 
                    page.recordCount() - 1 - page.nonDeletedRecordCount();


                if (num_possible_commit_delete > 0)
                {
                    // loop backward so that purges which affect the slot table 
                    // don't affect the loop (ie. they only move records we 
                    // have already looked at).
                    for (int slot_no = page.recordCount() - 1; 
                         slot_no > 0; 
                         slot_no--) 
                    {
                        if (page.isDeletedAtSlot(slot_no))
                        {


                            if (page.recordCount() == 2)
                            {
                                // About to purge last row from page so 
                                // remember the key so we can shrink the 
                                // tree.
                                shrink_key = this.getShrinkKey(
                                    open_btree, control_row, slot_no);
                            }


                            page.purgeAtSlot(slot_no, 1, true);


                            if (SanityManager.DEBUG)
                            {
                                if (SanityManager.DEBUG_ON(
                                        "verbose_btree_post_commit"))
                                {
                                    System.out.println(
                                        "Purging row[" + slot_no + "]" + 
                                        "on page:" + pageno + ".\n");
                                }
                            }
                        }
                    }
                }


                if (page.recordCount() == 1)
                {
                    if (SanityManager.DEBUG)
                    {
                        if (SanityManager.DEBUG_ON("verbose_btree_post_commit"))
                        {

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    Properties  prop,
    LevelInfo   level_info[])
        throws StandardException
    {
        LevelInfo li    = level_info[control_row.getLevel()];
        Page      page  = control_row.page;






        li.num_pages++;
        li.num_entries += (page.recordCount() - 1);
        li.num_deleted += (page.recordCount() - page.nonDeletedRecordCount());
        li.max_pageno  = Math.max(li.max_pageno, page.getPageNumber());


        DiagnosticUtil.findDiagnostic(page).diag_detail(prop);




        DiagnosticUtil.findDiagnostic(page).diag_detail(prop);

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                    {
                        scan_position.current_positionKey = 
                            runtime_mem.get_row_for_export();




                        Page page = scan_position.current_leaf.getPage();




                        RecordHandle rh =
                            page.fetchFromSlot(
                                (RecordHandle) null,
                                page.getSlotNumber(scan_position.current_rh), 
                                scan_position.current_positionKey, 
                                (FetchDescriptor) null,
                                true);


                        if (SanityManager.DEBUG)

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org.apache.derby.impl.store.access.btree.BranchControlRow

org.apache.derby.impl.store.access.btree.BTreeController

org.apache.derby.impl.store.access.btree.BTreeMaxScan

org.apache.derby.impl.store.access.btree.BTreePostCommit

org.apache.derby.impl.store.access.btree.BTreeScan

org.apache.derby.impl.store.access.btree.ControlRow

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org.apache.derby.impl.store.access.conglomerate.GenericScanController

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