src/backend/access/gist/gistscan.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * gistscan.c
   4  *        routines to manage scans on GiST index relations
   5  *
   6  *
   7  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
   8  * Portions Copyright (c) 1994, Regents of the University of California
   9  *
  10  * IDENTIFICATION
  11  *        $PostgreSQL$
  12  *
  13  *-------------------------------------------------------------------------
  14  */
  15 #include "postgres.h"
  16
  17 #include "access/genam.h"
  18 #include "access/gist_private.h"
  19 #include "access/gistscan.h"
  20 #include "access/relscan.h"
  21 #include "storage/bufmgr.h"
  22 #include "utils/memutils.h"
  23
  24 static void gistfreestack(GISTSearchStack *s);
  25
  26 Datum
  27 gistbeginscan(PG_FUNCTION_ARGS)
  28 {
  29         Relation        r = (Relation) PG_GETARG_POINTER(0);
  30         int                     nkeys = PG_GETARG_INT32(1);
  31         ScanKey         key = (ScanKey) PG_GETARG_POINTER(2);
  32         IndexScanDesc scan;
  33
  34         scan = RelationGetIndexScan(r, nkeys, key);
  35
  36         PG_RETURN_POINTER(scan);
  37 }
  38
  39 Datum
  40 gistrescan(PG_FUNCTION_ARGS)
  41 {
  42         IndexScanDesc scan = (IndexScanDesc) PG_GETARG_POINTER(0);
  43         ScanKey         key = (ScanKey) PG_GETARG_POINTER(1);
  44         GISTScanOpaque so;
  45         int                     i;
  46
  47         so = (GISTScanOpaque) scan->opaque;
  48         if (so != NULL)
  49         {
  50                 /* rescan an existing indexscan --- reset state */
  51                 gistfreestack(so->stack);
  52                 gistfreestack(so->markstk);
  53                 so->stack = so->markstk = NULL;
  54                 so->flags = 0x0;
  55                 /* drop pins on buffers -- no locks held */
  56                 if (BufferIsValid(so->curbuf))
  57                 {
  58                         ReleaseBuffer(so->curbuf);
  59                         so->curbuf = InvalidBuffer;
  60                 }
  61                 if (BufferIsValid(so->markbuf))
  62                 {
  63                         ReleaseBuffer(so->markbuf);
  64                         so->markbuf = InvalidBuffer;
  65                 }
  66
  67         }
  68         else
  69         {
  70                 /* initialize opaque data */
  71                 so = (GISTScanOpaque) palloc(sizeof(GISTScanOpaqueData));
  72                 so->stack = so->markstk = NULL;
  73                 so->flags = 0x0;
  74                 so->tempCxt = createTempGistContext();
  75                 so->curbuf = so->markbuf = InvalidBuffer;
  76                 so->giststate = (GISTSTATE *) palloc(sizeof(GISTSTATE));
  77                 initGISTstate(so->giststate, scan->indexRelation);
  78
  79                 scan->opaque = so;
  80         }
  81
  82         /*
  83          * Clear all the pointers.
  84          */
  85         ItemPointerSetInvalid(&so->curpos);
  86         ItemPointerSetInvalid(&so->markpos);
  87         so->nPageData = so->curPageData = 0;
  88
  89         /* Update scan key, if a new one is given */
  90         if (key && scan->numberOfKeys > 0)
  91         {
  92                 memmove(scan->keyData, key,
  93                                 scan->numberOfKeys * sizeof(ScanKeyData));
  94
  95                 /*
  96                  * Modify the scan key so that all the Consistent method is called for
  97                  * all comparisons. The original operator is passed to the Consistent
  98                  * function in the form of its strategy number, which is available
  99                  * from the sk_strategy field, and its subtype from the sk_subtype
 100                  * field.
 101                  */
 102                 for (i = 0; i < scan->numberOfKeys; i++)
 103                         scan->keyData[i].sk_func = so->giststate->consistentFn[scan->keyData[i].sk_attno - 1];
 104         }
 105
 106         PG_RETURN_VOID();
 107 }
 108
 109 Datum
 110 gistmarkpos(PG_FUNCTION_ARGS)
 111 {
 112         IndexScanDesc scan = (IndexScanDesc) PG_GETARG_POINTER(0);
 113         GISTScanOpaque so;
 114         GISTSearchStack *o,
 115                            *n,
 116                            *tmp;
 117
 118         so = (GISTScanOpaque) scan->opaque;
 119         so->markpos = so->curpos;
 120         if (so->flags & GS_CURBEFORE)
 121                 so->flags |= GS_MRKBEFORE;
 122         else
 123                 so->flags &= ~GS_MRKBEFORE;
 124
 125         o = NULL;
 126         n = so->stack;
 127
 128         /* copy the parent stack from the current item data */
 129         while (n != NULL)
 130         {
 131                 tmp = (GISTSearchStack *) palloc(sizeof(GISTSearchStack));
 132                 tmp->lsn = n->lsn;
 133                 tmp->parentlsn = n->parentlsn;
 134                 tmp->block = n->block;
 135                 tmp->next = o;
 136                 o = tmp;
 137                 n = n->next;
 138         }
 139
 140         gistfreestack(so->markstk);
 141         so->markstk = o;
 142
 143         /* Update markbuf: make sure to bump ref count on curbuf */
 144         if (BufferIsValid(so->markbuf))
 145         {
 146                 ReleaseBuffer(so->markbuf);
 147                 so->markbuf = InvalidBuffer;
 148         }
 149         if (BufferIsValid(so->curbuf))
 150         {
 151                 IncrBufferRefCount(so->curbuf);
 152                 so->markbuf = so->curbuf;
 153         }
 154
 155         so->markNPageData = so->nPageData;
 156         so->markCurPageData = so->curPageData;
 157         if ( so->markNPageData > 0 )
 158                 memcpy( so->markPageData, so->pageData, sizeof(ItemResult) * so->markNPageData );
 159
 160         PG_RETURN_VOID();
 161 }
 162
 163 Datum
 164 gistrestrpos(PG_FUNCTION_ARGS)
 165 {
 166         IndexScanDesc scan = (IndexScanDesc) PG_GETARG_POINTER(0);
 167         GISTScanOpaque so;
 168         GISTSearchStack *o,
 169                            *n,
 170                            *tmp;
 171
 172         so = (GISTScanOpaque) scan->opaque;
 173         so->curpos = so->markpos;
 174         if (so->flags & GS_MRKBEFORE)
 175                 so->flags |= GS_CURBEFORE;
 176         else
 177                 so->flags &= ~GS_CURBEFORE;
 178
 179         o = NULL;
 180         n = so->markstk;
 181
 182         /* copy the parent stack from the current item data */
 183         while (n != NULL)
 184         {
 185                 tmp = (GISTSearchStack *) palloc(sizeof(GISTSearchStack));
 186                 tmp->lsn = n->lsn;
 187                 tmp->parentlsn = n->parentlsn;
 188                 tmp->block = n->block;
 189                 tmp->next = o;
 190                 o = tmp;
 191                 n = n->next;
 192         }
 193
 194         gistfreestack(so->stack);
 195         so->stack = o;
 196
 197         /* Update curbuf: be sure to bump ref count on markbuf */
 198         if (BufferIsValid(so->curbuf))
 199         {
 200                 ReleaseBuffer(so->curbuf);
 201                 so->curbuf = InvalidBuffer;
 202         }
 203         if (BufferIsValid(so->markbuf))
 204         {
 205                 IncrBufferRefCount(so->markbuf);
 206                 so->curbuf = so->markbuf;
 207         }
 208
 209         so->nPageData = so->markNPageData;
 210         so->curPageData = so->markNPageData;
 211         if ( so->markNPageData > 0 )
 212                 memcpy( so->pageData, so->markPageData, sizeof(ItemResult) * so->markNPageData );
 213
 214         PG_RETURN_VOID();
 215 }
 216
 217 Datum
 218 gistendscan(PG_FUNCTION_ARGS)
 219 {
 220         IndexScanDesc scan = (IndexScanDesc) PG_GETARG_POINTER(0);
 221         GISTScanOpaque so;
 222
 223         so = (GISTScanOpaque) scan->opaque;
 224
 225         if (so != NULL)
 226         {
 227                 gistfreestack(so->stack);
 228                 gistfreestack(so->markstk);
 229                 if (so->giststate != NULL)
 230                         freeGISTstate(so->giststate);
 231                 /* drop pins on buffers -- we aren't holding any locks */
 232                 if (BufferIsValid(so->curbuf))
 233                         ReleaseBuffer(so->curbuf);
 234                 if (BufferIsValid(so->markbuf))
 235                         ReleaseBuffer(so->markbuf);
 236                 MemoryContextDelete(so->tempCxt);
 237                 pfree(scan->opaque);
 238         }
 239
 240         PG_RETURN_VOID();
 241 }
 242
 243 static void
 244 gistfreestack(GISTSearchStack *s)
 245 {
 246         while (s != NULL)
 247         {
 248                 GISTSearchStack *p = s->next;
 249
 250                 pfree(s);
 251                 s = p;
 252         }
 253 }