granicus.if.org Git - postgresql/blob - src/backend/executor/nodeFunctionscan.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * nodeFunctionscan.c
   4  *        Support routines for scanning RangeFunctions (functions in rangetable).
   5  *
   6  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
   7  * Portions Copyright (c) 1994, Regents of the University of California
   8  *
   9  *
  10  * IDENTIFICATION
  11  *        $Header: /cvsroot/pgsql/src/backend/executor/nodeFunctionscan.c,v 1.16 2002/12/15 16:17:46 tgl Exp $
  12  *
  13  *-------------------------------------------------------------------------
  14  */
  15 /*
  16  * INTERFACE ROUTINES
  17  *              ExecFunctionScan                scans a function.
  18  *              ExecFunctionNext                retrieve next tuple in sequential order.
  19  *              ExecInitFunctionScan    creates and initializes a functionscan node.
  20  *              ExecEndFunctionScan             releases any storage allocated.
  21  *              ExecFunctionReScan              rescans the function
  22  */
  23 #include "postgres.h"
  24
  25 #include "access/heapam.h"
  26 #include "catalog/pg_type.h"
  27 #include "executor/execdebug.h"
  28 #include "executor/execdefs.h"
  29 #include "executor/execdesc.h"
  30 #include "executor/nodeFunctionscan.h"
  31 #include "parser/parsetree.h"
  32 #include "parser/parse_expr.h"
  33 #include "parser/parse_type.h"
  34 #include "utils/lsyscache.h"
  35
  36
  37 static TupleTableSlot *FunctionNext(FunctionScanState *node);
  38 static bool tupledesc_mismatch(TupleDesc tupdesc1, TupleDesc tupdesc2);
  39
  40 /* ----------------------------------------------------------------
  41  *                                              Scan Support
  42  * ----------------------------------------------------------------
  43  */
  44 /* ----------------------------------------------------------------
  45  *              FunctionNext
  46  *
  47  *              This is a workhorse for ExecFunctionScan
  48  * ----------------------------------------------------------------
  49  */
  50 static TupleTableSlot *
  51 FunctionNext(FunctionScanState *node)
  52 {
  53         TupleTableSlot *slot;
  54         EState     *estate;
  55         ScanDirection direction;
  56         Tuplestorestate *tuplestorestate;
  57         bool            should_free;
  58         HeapTuple       heapTuple;
  59
  60         /*
  61          * get information from the estate and scan state
  62          */
  63         estate = node->ss.ps.state;
  64         direction = estate->es_direction;
  65
  66         tuplestorestate = node->tuplestorestate;
  67
  68         /*
  69          * If first time through, read all tuples from function and put them
  70          * in a tuplestore. Subsequent calls just fetch tuples from
  71          * tuplestore.
  72          */
  73         if (tuplestorestate == NULL)
  74         {
  75                 ExprContext *econtext = node->ss.ps.ps_ExprContext;
  76                 TupleDesc       funcTupdesc;
  77
  78                 node->tuplestorestate = tuplestorestate =
  79                         ExecMakeTableFunctionResult(node->funcexpr,
  80                                                                                 econtext,
  81                                                                                 node->tupdesc,
  82                                                                                 &funcTupdesc);
  83
  84                 /*
  85                  * If function provided a tupdesc, cross-check it.      We only really
  86                  * need to do this for functions returning RECORD, but might as
  87                  * well do it always.
  88                  */
  89                 if (funcTupdesc &&
  90                         tupledesc_mismatch(node->tupdesc, funcTupdesc))
  91                         elog(ERROR, "Query-specified return tuple and actual function return tuple do not match");
  92         }
  93
  94         /*
  95          * Get the next tuple from tuplestore. Return NULL if no more tuples.
  96          */
  97         slot = node->ss.ss_ScanTupleSlot;
  98         if (tuplestorestate)
  99                 heapTuple = tuplestore_getheaptuple(tuplestorestate,
 100                                                                            ScanDirectionIsForward(direction),
 101                                                                                         &should_free);
 102         else
 103         {
 104                 heapTuple = NULL;
 105                 should_free = false;
 106         }
 107
 108         return ExecStoreTuple(heapTuple, slot, InvalidBuffer, should_free);
 109 }
 110
 111 /* ----------------------------------------------------------------
 112  *              ExecFunctionScan(node)
 113  *
 114  *              Scans the function sequentially and returns the next qualifying
 115  *              tuple.
 116  *              It calls the ExecScan() routine and passes it the access method
 117  *              which retrieves tuples sequentially.
 118  *
 119  */
 120
 121 TupleTableSlot *
 122 ExecFunctionScan(FunctionScanState *node)
 123 {
 124         /*
 125          * use FunctionNext as access method
 126          */
 127         return ExecScan(&node->ss, (ExecScanAccessMtd) FunctionNext);
 128 }
 129
 130 /* ----------------------------------------------------------------
 131  *              ExecInitFunctionScan
 132  * ----------------------------------------------------------------
 133  */
 134 FunctionScanState *
 135 ExecInitFunctionScan(FunctionScan *node, EState *estate)
 136 {
 137         FunctionScanState *scanstate;
 138         RangeTblEntry *rte;
 139         Oid                     funcrettype;
 140         char            functyptype;
 141         TupleDesc       tupdesc = NULL;
 142
 143         /*
 144          * FunctionScan should not have any children.
 145          */
 146         Assert(outerPlan(node) == NULL);
 147         Assert(innerPlan(node) == NULL);
 148
 149         /*
 150          * create new ScanState for node
 151          */
 152         scanstate = makeNode(FunctionScanState);
 153         scanstate->ss.ps.plan = (Plan *) node;
 154         scanstate->ss.ps.state = estate;
 155
 156         /*
 157          * Miscellaneous initialization
 158          *
 159          * create expression context for node
 160          */
 161         ExecAssignExprContext(estate, &scanstate->ss.ps);
 162
 163 #define FUNCTIONSCAN_NSLOTS 2
 164
 165         /*
 166          * tuple table initialization
 167          */
 168         ExecInitResultTupleSlot(estate, &scanstate->ss.ps);
 169         ExecInitScanTupleSlot(estate, &scanstate->ss);
 170
 171         /*
 172          * initialize child expressions
 173          */
 174         scanstate->ss.ps.targetlist = (List *)
 175                 ExecInitExpr((Expr *) node->scan.plan.targetlist,
 176                                          (PlanState *) scanstate);
 177         scanstate->ss.ps.qual = (List *)
 178                 ExecInitExpr((Expr *) node->scan.plan.qual,
 179                                          (PlanState *) scanstate);
 180
 181         /*
 182          * get info about function
 183          */
 184         rte = rt_fetch(node->scan.scanrelid, estate->es_range_table);
 185         Assert(rte->rtekind == RTE_FUNCTION);
 186         funcrettype = exprType(rte->funcexpr);
 187
 188         /*
 189          * Now determine if the function returns a simple or composite type,
 190          * and build an appropriate tupdesc.
 191          */
 192         functyptype = get_typtype(funcrettype);
 193
 194         if (functyptype == 'c')
 195         {
 196                 /*
 197                  * Composite data type, i.e. a table's row type
 198                  */
 199                 Oid                     funcrelid;
 200                 Relation        rel;
 201
 202                 funcrelid = typeidTypeRelid(funcrettype);
 203                 if (!OidIsValid(funcrelid))
 204                         elog(ERROR, "Invalid typrelid for complex type %u",
 205                                  funcrettype);
 206                 rel = relation_open(funcrelid, AccessShareLock);
 207                 tupdesc = CreateTupleDescCopy(RelationGetDescr(rel));
 208                 relation_close(rel, AccessShareLock);
 209         }
 210         else if (functyptype == 'b' || functyptype == 'd')
 211         {
 212                 /*
 213                  * Must be a base data type, i.e. scalar
 214                  */
 215                 char       *attname = strVal(lfirst(rte->eref->colnames));
 216
 217                 tupdesc = CreateTemplateTupleDesc(1, false);
 218                 TupleDescInitEntry(tupdesc,
 219                                                    (AttrNumber) 1,
 220                                                    attname,
 221                                                    funcrettype,
 222                                                    -1,
 223                                                    0,
 224                                                    false);
 225         }
 226         else if (functyptype == 'p' && funcrettype == RECORDOID)
 227         {
 228                 /*
 229                  * Must be a pseudo type, i.e. record
 230                  */
 231                 tupdesc = BuildDescForRelation(rte->coldeflist);
 232         }
 233         else
 234                 elog(ERROR, "Unknown kind of return type specified for function");
 235
 236         scanstate->tupdesc = tupdesc;
 237         ExecSetSlotDescriptor(scanstate->ss.ss_ScanTupleSlot,
 238                                                   tupdesc, false);
 239
 240         /*
 241          * Other node-specific setup
 242          */
 243         scanstate->tuplestorestate = NULL;
 244         scanstate->funcexpr = ExecInitExpr((Expr *) rte->funcexpr,
 245                                                                            (PlanState *) scanstate);
 246
 247         scanstate->ss.ps.ps_TupFromTlist = false;
 248
 249         /*
 250          * initialize tuple type
 251          */
 252         ExecAssignResultTypeFromTL(&scanstate->ss.ps);
 253         ExecAssignProjectionInfo(&scanstate->ss.ps);
 254
 255         return scanstate;
 256 }
 257
 258 int
 259 ExecCountSlotsFunctionScan(FunctionScan *node)
 260 {
 261         return ExecCountSlotsNode(outerPlan(node)) +
 262                 ExecCountSlotsNode(innerPlan(node)) +
 263                 FUNCTIONSCAN_NSLOTS;
 264 }
 265
 266 /* ----------------------------------------------------------------
 267  *              ExecEndFunctionScan
 268  *
 269  *              frees any storage allocated through C routines.
 270  * ----------------------------------------------------------------
 271  */
 272 void
 273 ExecEndFunctionScan(FunctionScanState *node)
 274 {
 275         /*
 276          * Free the exprcontext
 277          */
 278         ExecFreeExprContext(&node->ss.ps);
 279
 280         /*
 281          * clean out the tuple table
 282          */
 283         ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
 284         ExecClearTuple(node->ss.ss_ScanTupleSlot);
 285
 286         /*
 287          * Release tuplestore resources
 288          */
 289         if (node->tuplestorestate != NULL)
 290                 tuplestore_end(node->tuplestorestate);
 291         node->tuplestorestate = NULL;
 292 }
 293
 294 /* ----------------------------------------------------------------
 295  *              ExecFunctionMarkPos
 296  *
 297  *              Calls tuplestore to save the current position in the stored file.
 298  * ----------------------------------------------------------------
 299  */
 300 void
 301 ExecFunctionMarkPos(FunctionScanState *node)
 302 {
 303         /*
 304          * if we haven't materialized yet, just return.
 305          */
 306         if (!node->tuplestorestate)
 307                 return;
 308
 309         tuplestore_markpos(node->tuplestorestate);
 310 }
 311
 312 /* ----------------------------------------------------------------
 313  *              ExecFunctionRestrPos
 314  *
 315  *              Calls tuplestore to restore the last saved file position.
 316  * ----------------------------------------------------------------
 317  */
 318 void
 319 ExecFunctionRestrPos(FunctionScanState *node)
 320 {
 321         /*
 322          * if we haven't materialized yet, just return.
 323          */
 324         if (!node->tuplestorestate)
 325                 return;
 326
 327         tuplestore_restorepos(node->tuplestorestate);
 328 }
 329
 330 /* ----------------------------------------------------------------
 331  *              ExecFunctionReScan
 332  *
 333  *              Rescans the relation.
 334  * ----------------------------------------------------------------
 335  */
 336 void
 337 ExecFunctionReScan(FunctionScanState *node, ExprContext *exprCtxt)
 338 {
 339         ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
 340
 341         /*
 342          * If we haven't materialized yet, just return.
 343          */
 344         if (!node->tuplestorestate)
 345                 return;
 346
 347         /*
 348          * Here we have a choice whether to drop the tuplestore (and recompute
 349          * the function outputs) or just rescan it.  This should depend on
 350          * whether the function expression contains parameters and/or is
 351          * marked volatile.  FIXME soon.
 352          */
 353         if (node->ss.ps.chgParam != NULL)
 354         {
 355                 tuplestore_end(node->tuplestorestate);
 356                 node->tuplestorestate = NULL;
 357         }
 358         else
 359                 tuplestore_rescan(node->tuplestorestate);
 360 }
 361
 362
 363 static bool
 364 tupledesc_mismatch(TupleDesc tupdesc1, TupleDesc tupdesc2)
 365 {
 366         int                     i;
 367
 368         if (tupdesc1->natts != tupdesc2->natts)
 369                 return true;
 370
 371         for (i = 0; i < tupdesc1->natts; i++)
 372         {
 373                 Form_pg_attribute attr1 = tupdesc1->attrs[i];
 374                 Form_pg_attribute attr2 = tupdesc2->attrs[i];
 375
 376                 /*
 377                  * We really only care about number of attributes and data type
 378                  */
 379                 if (attr1->atttypid != attr2->atttypid)
 380                         return true;
 381         }
 382
 383         return false;
 384 }