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// -*- Mode: C++ -*-
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// GiST.cpp
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//
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// Copyright (c) 1996, Regents of the University of California
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// $Header: /usr/local/devel/GiST/libGiST/libGiST/GiST.cpp,v 1.1.1.1 1996/08/06 23:47:20 jmh Exp $
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#include <stdio.h>
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#include <string.h>
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#include "GiST.h"
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#include "GiSTpath.h" // for GiSTRootPage
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GiST::GiST()
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{
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isOpen=0;
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debug=0;
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store=0;
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}
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void
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GiST::Create(const char *filename)
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{
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GiSTpage page;
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if(IsOpen()) return;
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store=CreateStore();
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store->Create(filename);
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if(!store->IsOpen()) return;
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page=store->Allocate();
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GiSTnode *node=NewNode(this);
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node->Path().MakeRoot();
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WriteNode(node);
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delete node;
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isOpen=1;
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}
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void
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GiST::Open(const char *filename)
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{
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if(IsOpen()) return;
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store=CreateStore();
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store->Open(filename);
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if(!store->IsOpen()) return;
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isOpen=1;
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}
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void
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GiST::Close()
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{
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if(IsOpen()) {
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store->Close();
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isOpen=0;
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}
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}
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void
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GiST::Insert(const GiSTentry &entry)
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{
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InsertHelper(entry, 0);
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}
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void
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GiST::InsertHelper(const GiSTentry &entry,
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int level, // level of tree at which to insert
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int *splitvec) // a vector to trigger Split instead of forced reinsert
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{
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GiSTnode *leaf;
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int overflow=0;
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leaf=ChooseSubtree(GiSTRootPage, entry, level);
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leaf->Insert(entry);
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if (leaf->IsOverFull(*store)) {
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if(ForcedReinsert()&&!leaf->Path().IsRoot()&&(!splitvec||!splitvec[level])) {
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int split[GIST_MAX_LEVELS];
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// R*-tree-style forced reinsert
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for(int i=0; i<GIST_MAX_LEVELS; i++) split[i]=0;
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OverflowTreatment(leaf, entry, split);
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overflow=1;
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}
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else Split(&leaf, entry);
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if(leaf->IsOverFull(*store)) {
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// we only should get here if we reinserted, and the node re-filled
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assert(overflow);
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leaf->DeleteEntry(entry.Position());
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Split(&leaf, entry);
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}
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}
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else WriteNode(leaf);
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if(!overflow) AdjustKeys(leaf, NULL);
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delete leaf;
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}
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void
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GiST::OverflowTreatment(GiSTnode *node, const GiSTentry& entry, int *splitvec)
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{
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GiSTlist<GiSTentry*> deleted;
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// remove the "top" p entries from the node
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deleted=RemoveTop(node);
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WriteNode(node);
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AdjustKeys(node, NULL);
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// note that we've seen this level already
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splitvec[node->Level()]=1;
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// for each of the deleted entries, call InsertHelper at this level
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while (!deleted.IsEmpty()) {
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GiSTentry *tmpentry=deleted.RemoveFront();
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InsertHelper(*tmpentry, node->Level(), splitvec);
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delete tmpentry;
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}
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}
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GiSTlist<GiSTentry*>
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GiST::RemoveTop(GiSTnode *node)
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{
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GiSTlist<GiSTentry*> deleted;
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int count=node->NumEntries();
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// default: remove the first ones on the page
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int num_rem=(int)((count+1)*RemoveRatio()+0.5);
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for(int i=num_rem-1; i>=0; i--) {
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deleted.Append((GiSTentry *)(*node)[i].Ptr()->Copy());
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node->DeleteEntry(i);
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}
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return(deleted);
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}
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void
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GiST::AdjustKeys(GiSTnode *node, GiSTnode **parent)
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{
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GiSTnode *P;
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if(node->Path().IsRoot()) return;
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// Read in node's parent
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if(parent==NULL) {
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GiSTpath parent_path=node->Path();
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parent_path.MakeParent();
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P=ReadNode(parent_path);
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parent=&P;
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}
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else P=*parent;
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// Get the old entry pointing to node
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GiSTentry *entry=P->SearchPtr(node->Path().Page());
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assert(entry!=NULL);
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// Get union of node
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GiSTentry *actual=node->Union();
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actual->SetPtr(node->Path().Page());
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if(!entry->IsEqual(*actual)) {
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int pos=entry->Position();
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P->DeleteEntry(pos);
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P->InsertBefore(*actual, pos);
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// A split may be necessary.
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// XXX: should we do Forced Reinsert here too?
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if(P->IsOverFull(*store)) {
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Split(parent, *actual);
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GiSTpage page=node->Path().Page();
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node->Path()=P->Path();
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node->Path().MakeChild(page);
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}
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else {
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WriteNode(P);
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AdjustKeys(P, NULL);
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}
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}
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if(parent==&P) delete P;
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delete actual;
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delete entry;
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}
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void
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GiST::Sync()
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{
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store->Sync();
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}
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void
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GiST::Delete(const GiSTpredicate& pred)
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{
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GiSTcursor *c=Search(pred);
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int condensed;
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GiSTentry *e;
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do {
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if(c==NULL) return;
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e=c->Next();
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GiSTpath path=c->Path();
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delete c;
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if(e==NULL) return;
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// Read in the node that this belongs to
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GiSTnode *node=ReadNode(path);
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node->DeleteEntry(e->Position());
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WriteNode(node);
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condensed=CondenseTree(node);
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delete node;
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if(condensed) {
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ShortenTree();
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// because the tree changed, we need to search all over again!
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// XXX - this is inefficient! users may want to avoid condensing.
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c=Search(pred);
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}
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} while(e!=NULL);
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}
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void
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GiST::ShortenTree()
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{
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GiSTpath path;
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// Shorten the tree if necessary (This should only be done if root actually changed!)
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path.MakeRoot();
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GiSTnode *root=ReadNode(path);
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if(!root->IsLeaf()&&root->NumEntries()==1) {
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path.MakeChild((*root)[0]->Ptr());
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GiSTnode *child=ReadNode(path);
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store->Deallocate(path.Page());
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child->SetSibling(0);
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child->Path().MakeRoot();
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WriteNode(child);
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delete child;
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}
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delete root;
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}
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// handle underfull leaf nodes
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int
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GiST::CondenseTree(GiSTnode *node)
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{
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GiSTlist<GiSTentry*> Q;
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int deleted=0;
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// Must be condensing a leaf
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assert(node->IsLeaf());
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while(!node->Path().IsRoot()) {
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GiSTpath parent_path=node->Path();
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parent_path.MakeParent();
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GiSTnode *P=ReadNode(parent_path);
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GiSTentry *En=P->SearchPtr(node->Path().Page());
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assert(En!=NULL);
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// Handle under-full node
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if(node->IsUnderFull(*store)) {
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if(!IsOrdered()) {
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TruePredicate truePredicate;
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GiSTlist<GiSTentry*> list=node->Search(truePredicate);
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while(!list.IsEmpty()) {
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GiSTentry *e=list.RemoveFront();
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Q.Append(e);
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}
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P->DeleteEntry(En->Position());
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WriteNode(P);
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deleted=1;
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AdjustKeys(P, NULL);
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}
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else {
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// Try to borrow entries, else coalesce with a neighbor
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// Have to look at left sibling???
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GiSTpage neighbor_page=P->SearchNeighbors(node->Path().Page());
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GiSTpath neighbor_path=node->Path();
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neighbor_path.MakeSibling(neighbor_page);
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if(neighbor_page!=0) {
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GiSTnode *neighbor;
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// If neighbor is RIGHT sibling...
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if(node->Sibling()==neighbor_page) neighbor=ReadNode(neighbor_path);
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else {
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neighbor=node;
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node=ReadNode(neighbor_path);
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}
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GiSTentry *e=P->SearchPtr(node->Path().Page());
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node->Coalesce(*neighbor, *e);
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delete e;
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// If not overfull, coalesce, kill right node
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if(!node->IsOverFull(*store)) {
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node->SetSibling(neighbor->Sibling());
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WriteNode(node);
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// Delete the neighbor from parent
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GiSTentry *e=P->SearchPtr(neighbor->Path().Page());
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P->DeleteEntry(e->Position());
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WriteNode(P);
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delete e;
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store->Deallocate(neighbor->Path().Page());
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deleted=1;
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}
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// If overfull, split (same as borrowing)
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else {
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GiSTnode *node2=node->PickSplit();
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node2->Path()=neighbor->Path();
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node2->SetSibling(neighbor->Sibling());
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WriteNode(node);
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WriteNode(node2);
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AdjustKeys(node2, &P);
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delete node2;
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deleted=1;
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}
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delete neighbor;
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}
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}
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}
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// Adjust covering predicate
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if(!deleted) AdjustKeys(node, &P);
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parent_path=node->Path();
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parent_path.MakeParent();
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delete node;
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// Propagate deletes
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if(!deleted) break;
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node=P;
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}
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// Re-insert orphaned entries
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while(!Q.IsEmpty()) {
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GiSTentry *e=Q.RemoveFront();
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InsertHelper(*e, e->Level());
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delete e;
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}
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return(deleted);
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}
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GiSTnode*
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GiST::ChooseSubtree(GiSTpage page, const GiSTentry &entry, int level)
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{
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GiSTnode *node;
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GiSTpath path;
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for(;;) {
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path.MakeChild(page);
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node=ReadNode(path);
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if(level==node->Level()||node->IsLeaf()) break;
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page=node->SearchMinPenalty(entry);
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delete node;
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}
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return node;
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}
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void
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GiST::Split(GiSTnode **node, const GiSTentry& entry)
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{
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int went_left=0, new_root=0;
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if((*node)->Path().IsRoot()) {
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new_root=1;
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(*node)->Path().MakeChild(store->Allocate());
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}
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GiSTnode *node2=(*node)->PickSplit();
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node2->Path().MakeSibling(store->Allocate());
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GiSTentry *e=(*node)->SearchPtr(entry.Ptr());
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if(e!=NULL) {
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went_left=1;
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delete e;
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}
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node2->SetSibling((*node)->Sibling());
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(*node)->SetSibling(node2->Path().Page());
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WriteNode(*node);
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WriteNode(node2);
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GiSTentry *e1=(*node)->Union();
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GiSTentry *e2=node2->Union();
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e1->SetPtr((*node)->Path().Page());
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e2->SetPtr(node2->Path().Page());
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// Create new root if root is being split
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if (new_root) {
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GiSTnode *root=NewNode(this);
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root->SetLevel((*node)->Level()+1);
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root->InsertBefore(*e1, 0);
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root->InsertBefore(*e2, 1);
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root->Path().MakeRoot();
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WriteNode(root);
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delete root;
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}
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else {
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// Insert entry for N' in parent
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GiSTpath parent_path=(*node)->Path();
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parent_path.MakeParent();
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GiSTnode *parent=ReadNode(parent_path);
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// Find the entry for N in parent
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GiSTentry *e=parent->SearchPtr((*node)->Path().Page());
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assert(e!=NULL);
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// Insert the new entry right after it
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int pos=e->Position();
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parent->DeleteEntry(pos);
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parent->InsertBefore(*e1, pos);
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parent->InsertBefore(*e2, pos+1);
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delete e;
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if(!parent->IsOverFull(*store)) WriteNode(parent);
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else {
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Split(&parent, went_left? *e1: *e2);
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GiSTpage page=(*node)->Path().Page();
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(*node)->Path()=parent->Path();
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(*node)->Path().MakeChild(page);
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page=node2->Path().Page();
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node2->Path()=(*node)->Path();
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node2->Path().MakeSibling(page);
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}
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delete parent;
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}
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if(!went_left) {
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delete *node;
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*node=node2;
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}
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else delete node2;
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delete e1;
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delete e2;
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}
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GiSTnode*
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GiST::ReadNode(const GiSTpath& path) const
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{
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char *buf=new char[store->PageSize()];
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GiSTnode *node=NewNode((GiST *)this);
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store->Read(path.Page(), buf);
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node->Unpack(buf);
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#ifdef PRINTING_OBJECTS
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if(debug) {
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cout << "READ PAGE " << path.Page() << ":\n";
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node->Print(cout);
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}
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#endif
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node->Path()=path;
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delete []buf;
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return node;
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}
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void
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GiST::WriteNode(GiSTnode *node)
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{
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char *buf=new char[store->PageSize()];
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// make Purify happy
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memset(buf, 0, store->PageSize());
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#ifdef PRINTING_OBJECTS
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if(debug) {
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cout << "WRITE PAGE " << node->Path().Page() << ":\n";
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node->Print(cout);
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}
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#endif
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node->Pack(buf);
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store->Write(node->Path().Page(), buf);
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delete buf;
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}
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#ifdef PRINTING_OBJECTS
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void
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GiST::DumpNode(ostream& os, GiSTpath path) const
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{
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GiSTnode *node=ReadNode(path);
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477 |
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node->Print(os);
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if(!node->IsLeaf()) {
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TruePredicate truePredicate;
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GiSTlist<GiSTentry*> list=node->Search(truePredicate);
|
482 |
|
483 |
while (!list.IsEmpty()) {
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GiSTentry *e=list.RemoveFront();
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485 |
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path.MakeChild(e->Ptr());
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DumpNode(os, path);
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path.MakeParent();
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delete e;
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}
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}
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delete node;
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}
|
494 |
|
495 |
void
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496 |
GiST::Print(ostream& os) const
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497 |
{
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498 |
GiSTpath path;
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499 |
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path.MakeRoot();
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DumpNode(os, path);
|
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}
|
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#endif
|
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506 |
GiSTcursor*
|
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GiST::Search(const GiSTpredicate &query) const
|
508 |
{
|
509 |
return new GiSTcursor(*this, query);
|
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}
|
511 |
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512 |
GiST::~GiST()
|
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{
|
514 |
Close();
|
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delete store;
|
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}
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