nodeGroup.c 10.3 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
/*-------------------------------------------------------------------------
 *
 * nodeGroup.c--
 *    Routines to handle group nodes (used for queries with GROUP BY clause).
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 *
 * DESCRIPTION
 *    The Group node is designed for handling queries with a GROUP BY clause.
 *    It's outer plan must be a sort node. It assumes that the tuples it gets
 *    back from the outer plan is sorted in the order specified by the group
 *    columns. (ie. tuples from the same group are consecutive)
 *
 * IDENTIFICATION
Bruce Momjian's avatar
Bruce Momjian committed
16
 *    $Header: /cvsroot/pgsql/src/backend/executor/nodeGroup.c,v 1.4 1996/11/08 20:45:20 momjian Exp $
17 18 19
 *
 *-------------------------------------------------------------------------
 */
20
#include "postgres.h"
Bruce Momjian's avatar
Bruce Momjian committed
21
#include "fmgr.h"
22

23 24
#include "access/heapam.h"
#include "catalog/catalog.h"
Bruce Momjian's avatar
Bruce Momjian committed
25
#include "access/printtup.h"
26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411
#include "executor/executor.h"
#include "executor/nodeGroup.h"

static TupleTableSlot *ExecGroupEveryTuple(Group *node);
static TupleTableSlot *ExecGroupOneTuple(Group *node);
static bool sameGroup(TupleTableSlot *oldslot, TupleTableSlot *newslot,
		      int numCols, AttrNumber *grpColIdx, TupleDesc tupdesc);

/* ---------------------------------------
 *   ExecGroup -
 *
 *	There are two modes in which tuples are returned by ExecGroup. If
 *	tuplePerGroup is TRUE, every tuple from the same group will be
 *	returned, followed by a NULL at the end of each group. This is
 *	useful for Agg node which needs to aggregate over tuples of the same
 *	group. (eg. SELECT salary, count{*} FROM emp GROUP BY salary)
 *
 *	If tuplePerGroup is FALSE, only one tuple per group is returned. The
 *	tuple returned contains only the group columns. NULL is returned only
 *	at the end when no more groups is present. This is useful when
 *	the query does not involve aggregates. (eg. SELECT salary FROM emp
 *	GROUP BY salary)
 * ------------------------------------------
 */
TupleTableSlot *
ExecGroup(Group *node)
{
    if (node->tuplePerGroup)
	return ExecGroupEveryTuple(node);
    else
	return ExecGroupOneTuple(node);
}

/*
 * ExecGroupEveryTuple -
 *   return every tuple with a NULL between each group
 */
static TupleTableSlot *
ExecGroupEveryTuple(Group *node)
{
    GroupState		*grpstate;
    EState		*estate;
    ExprContext		*econtext;

    HeapTuple 		outerTuple = NULL;
    TupleTableSlot 	*outerslot, *lastslot;
    ProjectionInfo	*projInfo;
    TupleTableSlot	*resultSlot;

    bool isDone;

    /* ---------------------
     *  get state info from node
     * ---------------------
     */
    grpstate = node->grpstate;
    if (grpstate->grp_done)
	return NULL;

    estate = node->plan.state;

    econtext = grpstate->csstate.cstate.cs_ExprContext;

    if (grpstate->grp_useLastTuple) {
	/*
	 * we haven't returned last tuple yet because it is not of the
	 * same group
	 */
	grpstate->grp_useLastTuple = FALSE;

	ExecStoreTuple(grpstate->grp_lastSlot->val,
		       grpstate->csstate.css_ScanTupleSlot,
		       grpstate->grp_lastSlot->ttc_buffer,
		       false);
    } else {
	outerslot = ExecProcNode(outerPlan(node), (Plan*)node);
	if (outerslot)
	    outerTuple = outerslot->val;
	if (!HeapTupleIsValid(outerTuple)) {
	    grpstate->grp_done = TRUE;
	    return NULL;
	}

	/* ----------------
	 *  Compare with last tuple and see if this tuple is of
	 *  the same group.
	 * ----------------
	 */
	lastslot = grpstate->csstate.css_ScanTupleSlot;

	if (lastslot->val != NULL &&
	    (!sameGroup(lastslot, outerslot,
			node->numCols, node->grpColIdx,
			ExecGetScanType(&grpstate->csstate)))) {
/*			ExecGetResultType(&grpstate->csstate.cstate)))) {*/

	    grpstate->grp_useLastTuple = TRUE;

	    /* save it for next time */
	    grpstate->grp_lastSlot = outerslot;

	    /*
	     * signifies the end of the group 
	     */
	    return NULL;
	}
	
	ExecStoreTuple(outerTuple,
		       grpstate->csstate.css_ScanTupleSlot,
		       outerslot->ttc_buffer,
		       false);
    }

    /* ----------------
     *	form a projection tuple, store it in the result tuple
     *  slot and return it.
     * ----------------
     */
    projInfo = grpstate->csstate.cstate.cs_ProjInfo;

    econtext->ecxt_scantuple = grpstate->csstate.css_ScanTupleSlot;
    resultSlot = ExecProject(projInfo, &isDone);
    
    return resultSlot;
}

/*
 * ExecGroupOneTuple -
 *    returns one tuple per group, a NULL at the end when there are no more
 *    tuples.
 */
static TupleTableSlot *
ExecGroupOneTuple(Group *node)
{
    GroupState		*grpstate;
    EState		*estate;
    ExprContext		*econtext;

    HeapTuple 		outerTuple = NULL;
    TupleTableSlot 	*outerslot, *lastslot;
    ProjectionInfo	*projInfo;
    TupleTableSlot	*resultSlot;

    bool isDone;

    /* ---------------------
     *  get state info from node
     * ---------------------
     */
    grpstate = node->grpstate;
    if (grpstate->grp_done)
	return NULL;

    estate = node->plan.state;

    econtext = node->grpstate->csstate.cstate.cs_ExprContext;

    if (grpstate->grp_useLastTuple) {
	grpstate->grp_useLastTuple = FALSE;
	ExecStoreTuple(grpstate->grp_lastSlot->val,
		       grpstate->csstate.css_ScanTupleSlot,
		       grpstate->grp_lastSlot->ttc_buffer,
		       false);
    } else {
	outerslot = ExecProcNode(outerPlan(node), (Plan*)node);
	if (outerslot) outerTuple = outerslot->val;
	if (!HeapTupleIsValid(outerTuple)) {
	    grpstate->grp_done = TRUE;
	    return NULL;
	}
	ExecStoreTuple(outerTuple,
		       grpstate->csstate.css_ScanTupleSlot,
		       outerslot->ttc_buffer,
		       false);
    }
    lastslot = grpstate->csstate.css_ScanTupleSlot;

    /*
     * find all tuples that belong to a group
     */
    for(;;) {
	outerslot = ExecProcNode(outerPlan(node), (Plan*)node);
	outerTuple = (outerslot) ? outerslot->val : NULL;
	if (!HeapTupleIsValid(outerTuple)) {
	    /*
	     * we have at least one tuple (lastslot) if we reach here
	     */
	    grpstate->grp_done = TRUE;

	    /* return lastslot */
	    break;
	}

        /* ----------------
	 *  Compare with last tuple and see if this tuple is of
	 *  the same group.
	 * ----------------
	 */
	if ((!sameGroup(lastslot, outerslot,
			node->numCols, node->grpColIdx,
			ExecGetScanType(&grpstate->csstate)))) {
/*			ExecGetResultType(&grpstate->csstate.cstate)))) {*/

	    grpstate->grp_useLastTuple = TRUE;

	    /* save it for next time */
	    grpstate->grp_lastSlot = outerslot;

	    /* return lastslot */
	    break; 
	}
	
	ExecStoreTuple(outerTuple,
		       grpstate->csstate.css_ScanTupleSlot,
		       outerslot->ttc_buffer,
		       false);

	lastslot = grpstate->csstate.css_ScanTupleSlot;
    }

    ExecStoreTuple(lastslot->val,
		   grpstate->csstate.css_ScanTupleSlot,
		   lastslot->ttc_buffer,
		   false);

    /* ----------------
     *	form a projection tuple, store it in the result tuple
     *  slot and return it.
     * ----------------
     */
    projInfo = grpstate->csstate.cstate.cs_ProjInfo;

    econtext->ecxt_scantuple = lastslot;
    resultSlot = ExecProject(projInfo, &isDone);
    
    return resultSlot;
}

/* -----------------
 * ExecInitGroup 
 *
 *  Creates the run-time information for the group node produced by the
 *  planner and initializes its outer subtree
 * -----------------
 */
bool
ExecInitGroup(Group *node, EState *estate, Plan *parent)
{
    GroupState		*grpstate;
    Plan		*outerPlan;
    
    /* 
     * assign the node's execution state
     */
    node->plan.state = estate;
    
    /*
     * create state structure
     */
    grpstate = makeNode(GroupState);
    node->grpstate = grpstate;
    grpstate->grp_useLastTuple = FALSE;
    grpstate->grp_done = FALSE;

    /*
     * assign node's base id and create expression context
     */
    ExecAssignNodeBaseInfo(estate, &grpstate->csstate.cstate,
			   (Plan*) parent);
    ExecAssignExprContext(estate, &grpstate->csstate.cstate);
    
#define GROUP_NSLOTS 2
    /*
     * tuple table initialization
     */
    ExecInitScanTupleSlot(estate, &grpstate->csstate);
    ExecInitResultTupleSlot(estate, &grpstate->csstate.cstate);

    /*
     * initializes child nodes
     */
    outerPlan = outerPlan(node);
    ExecInitNode(outerPlan, estate, (Plan *)node);
    
    /* ----------------
     * 	initialize tuple type.
     * ----------------
     */
    ExecAssignScanTypeFromOuterPlan((Plan *) node, &grpstate->csstate); 

    /*
     * Initialize tuple type for both result and scan.
     * This node does no projection
     */
    ExecAssignResultTypeFromTL((Plan*) node, &grpstate->csstate.cstate);
    ExecAssignProjectionInfo((Plan*)node, &grpstate->csstate.cstate);

    return TRUE;
}

int
ExecCountSlotsGroup(Group *node)
{
    return ExecCountSlotsNode(outerPlan(node)) + GROUP_NSLOTS;
}

/* ------------------------
 *	ExecEndGroup(node)
 *
 * -----------------------
 */
void
ExecEndGroup(Group *node)
{
    GroupState	*grpstate;
    Plan	*outerPlan;

    grpstate = node->grpstate;

    ExecFreeProjectionInfo(&grpstate->csstate.cstate);

    outerPlan = outerPlan(node);
    ExecEndNode(outerPlan, (Plan*)node);
    
    /* clean up tuple table */
    ExecClearTuple(grpstate->csstate.css_ScanTupleSlot);
}

/*****************************************************************************
 *
 *****************************************************************************/

/*
 * code swiped from nodeUnique.c
 */
static bool
sameGroup(TupleTableSlot *oldslot,
	  TupleTableSlot *newslot,
	  int		 numCols,
	  AttrNumber	 *grpColIdx,
	  TupleDesc	 tupdesc)
{
    bool isNull1,isNull2;
    char *attr1, *attr2;
    char *val1, *val2;
    int i;
    AttrNumber att;
    Oid typoutput;

    for(i = 0; i < numCols; i++) {
	att = grpColIdx[i];
	typoutput = typtoout((Oid)tupdesc->attrs[att-1]->atttypid);    

	attr1 = heap_getattr(oldslot->val,
			     InvalidBuffer,
			     att,
			     tupdesc,
			     &isNull1);

	attr2 = heap_getattr(newslot->val,
			     InvalidBuffer, 
			     att,
			     tupdesc,
			     &isNull2);
			     
	if (isNull1 == isNull2) {
	    if (isNull1) /* both are null, they are equal */
	      continue;

	    val1 = fmgr(typoutput, attr1,
			gettypelem(tupdesc->attrs[att-1]->atttypid));
	    val2 = fmgr(typoutput, attr2,
			gettypelem(tupdesc->attrs[att-1]->atttypid));

	    /* now, val1 and val2 are ascii representations so we can
	       use strcmp for comparison */
	    if (strcmp(val1,val2) != 0)
		return FALSE;
	} else {
	    /* one is null and the other isn't, they aren't equal */
	    return FALSE;
	}
    }

    return TRUE;
}