1: # include   <ingres.h>
   2: # include   <aux.h>
   3: # include   <tree.h>
   4: # include   <symbol.h>
   5: # include   "globs.h"
   6: # include   <sccs.h>
   7: # include   <errors.h>
   8: 
   9: SCCSID(@(#)decomp.c	8.3	12/18/85)
  10: 
  11: /*
  12: ** DECOMP -- Process a query given a query tree and range table.
  13: **
  14: **	Decomp processes any arbitrary query by converting it into
  15: **	a sequence of "one variable queries"; eg. queries involving
  16: **	at most one source relation. This file and decision.c contain
  17: **	the principle decision making routines.
  18: **
  19: **	Decomp() is called with a pointer to a query tree, the mode
  20: **	of the query (retrieve, append, etc.), and the internal name
  21: **	of the result relation (if any). The routines included are:
  22: **
  23: **	Decomp  -- Opens the source relations and decides whether the
  24: **			query is multi-variable or single/zero variable.
  25: **
  26: **	Decompx -- Takes a multivariable query, removes and executes any
  27: **			one-var restrictions and passes the remaining query
  28: **			to decompz (if one/zero variable) or decision().
  29: **
  30: **	Decompy -- Performs "tuple substitution" on a multi-var query,
  31: **			does any new one-var restrictions and passes the
  32: **			remaining query to decompz (if one/zero variable)
  33: **			or decision().
  34: **
  35: **	Decompz -- Executes a one/zero variable query by calling call_ovqp().
  36: */
  37: /*
  38: **	Process query by calling either decompx for multivar
  39: **	or decompz for 0 or 1 var query. Decomp() must guarantee
  40: **	that the range table is the same upon exiting as it was
  41: **	when entered. Newquery() and endquery() perform that function.
  42: **
  43: **	Trace Flags:
  44: **		30
  45: */
  46: 
  47: decomp(q, qmode, result_num)
  48: QTREE   *q;
  49: int qmode;
  50: int result_num;
  51: {
  52:     register QTREE  *root;
  53:     register int    vc, i;
  54:     int     locrange[MAXRANGE];
  55: 
  56:     root = q;
  57:     vc = root->sym.value.sym_root.tvarc;
  58: #	ifdef xDTR1
  59:     if (tTf(30, 0))
  60:         printf("DECOMP: %d-var query, result_num=%d\n", vc, result_num);
  61:     if (tTf(30, 1))
  62:     {
  63:         printf("DECOMP\n");
  64:         treepr(root);
  65:     }
  66: #	endif
  67: 
  68:     openrs(root);
  69: 
  70:     if (vc > 1)
  71:     {
  72:         newquery(locrange);
  73:         i = decompx(root, qmode, result_num);
  74:         endquery(locrange, FALSE);  /* don't reopen previous range */
  75:     }
  76:     else
  77:     {
  78:         De.de_newq = 1;
  79:         De.de_sourcevar = -1;
  80:         i = decompz(root, qmode, result_num);
  81:     }
  82: 
  83:     /*
  84: 	** remove the range variables that the view subsystem
  85: 	** might have placed in.
  86: 	*/
  87:     clrrange();
  88: 
  89:     return (i);
  90: }
  91: /*
  92: ** Decompx -- Initialize for multi-variable query.
  93: **	All one-variable subqueries are run.
  94: **	If the remaining query is still multi-var
  95: **	then decision() is called; else decompz()
  96: **	is called. The range table is restored
  97: **	after the query is complete.
  98: **	The tempvars from the exec_sq() are left on the
  99: **	tree since it is presumed that the tree will be discarded
 100: **	anyway.
 101: **
 102: **	Trace Flags:
 103: **		31
 104: */
 105: 
 106: decompx(root, qmode, result_num)
 107: QTREE   *root;
 108: int qmode;
 109: int result_num;
 110: {
 111:     register int    i, vc;
 112:     int     disj;
 113:     int         sqbuf[1+SQSIZ/sizeof(int)];
 114:     QTREE       *sqlist[MAXRANGE];
 115:     int     locrang[MAXRANGE], sqrange[MAXRANGE];
 116:     extern int  derror();
 117: 
 118:     vc = root->sym.value.sym_root.tvarc;
 119:     initbuf((char *)sqbuf, SQSIZ, SQBUFFULL, derror);
 120:     pull_sq(root, sqlist, locrang, sqrange, (char *)sqbuf);
 121:     if ((i = exec_sq(sqlist, sqrange, &disj)) != -1)
 122:     {
 123:         undo_sq(sqlist, locrang, sqrange, i, i, FALSE);
 124:         return (FALSE);
 125:     }
 126:     vc -= disj;
 127:     tempvar(root, sqlist, (char *)sqbuf);
 128:     if (pull_const(root, (char *)sqbuf) == 0)
 129:         return (FALSE);
 130:     if (vc <= 1)
 131:     {
 132:         De.de_sourcevar = -1;
 133:         De.de_newq = 1;
 134:         return (decompz(root, qmode, result_num));
 135:     }
 136:     i = decision(root, qmode, result_num, (char *)sqbuf);
 137:     undo_sq(sqlist, locrang, sqrange, MAXRANGE, MAXRANGE, FALSE);
 138:     return (i);
 139: }
 140: /*
 141: ** Decompy -- decompose a multi-variable query by tuple substitution.
 142: **	First a variable is selected
 143: **	for substitution. Then for each tuple in the
 144: **	selected variable, all one variable restrictions
 145: **	are done (exec_sq) and the remaining query is
 146: **	solved by calling either decompz() or recursively
 147: **	decision().
 148: **
 149: **	The original tree and range table are guaranteed to
 150: **	be the same on entry and exit (modulo the effects of
 151: **	reformat()).
 152: **
 153: **	Trace Flags:
 154: **		32
 155: */
 156: 
 157: decompy(q, qmode, result_num, sqbuf)
 158: QTREE   *q;
 159: int qmode;
 160: int result_num;
 161: char    *sqbuf;
 162: {
 163:     register QTREE  *root;
 164:     register int    j, vc;
 165:     DESC        *d;
 166:     QTREE       *newroot;
 167:     int     constl, sqcnt, var, srcvar, maxsqcnt;
 168:     int     disj, tc, qtrue;
 169:     TID     tid, hitid;
 170:     char        *tuple;
 171:     QTREE       *sqlist[MAXRANGE];
 172:     int     sqmark, sqmark1;
 173:     int     locrang[MAXRANGE], sqrange[MAXRANGE];
 174:     extern DESC *readopen();
 175:     extern char *need(), *rangename();
 176:     extern QTREE    *copy_ands();
 177: 
 178:     root = q;
 179:     vc = root->sym.value.sym_root.tvarc;
 180: 
 181: #	ifdef xDTR1
 182:     if (tTf(32, -1))
 183:         printf("DECOMPY:%x,vc=%d\n", root, vc);
 184: #	endif
 185: 
 186:     sqmark = markbuf(sqbuf);
 187:     constl = !root->sym.value.sym_root.lvarc;
 188:     qtrue = FALSE;
 189: 
 190:     if ((var = selectv(root)) < 0)
 191:         return (qtrue);
 192:     d = readopen(var);  /* gets full descriptor for setvar & get */
 193:     tuple = need(sqbuf, d->reldum.relwid);
 194:     setvar(root, var, &tid, tuple);
 195:     pull_sq(root, sqlist, locrang, sqrange, sqbuf);
 196:     tempvar(root, sqlist, sqbuf);
 197:     reformat(var, sqlist, locrang, sqbuf, root);
 198:     vc--;
 199: # ifdef xDTR2
 200:     if (tTf(32, 0))
 201:     {
 202:         printf("DECOMPY: &tup=%x, ", tuple);
 203:         printdesc(d);
 204:     }
 205: # endif xDTR2
 206: 
 207:     /* HERE FOR MULTI-VAR SUBSTITUTION */
 208:     sqmark1 = markbuf(sqbuf);
 209:     De.de_newq = 1;
 210:     tc = 0;
 211:     sqcnt = maxsqcnt = 0;
 212:     srcvar = -1;
 213:     De.de_sourcevar = -1;
 214:     find(readopen(var), NOKEY, &tid, &hitid);
 215:     while (!(j=get(readopen(var), &tid, &hitid, tuple, NXTTUP)))
 216:     {
 217: #		ifdef xDTR1
 218:         if (tTf(32, 2))
 219:         {
 220:             printf("Subst:");
 221:             printup(readopen(var), tuple);
 222:         }
 223: #		endif
 224:         tc++;
 225:         if (vc > 1)
 226:         {
 227:             reset_sq(sqlist, locrang, sqcnt);
 228:             if ((sqcnt = exec_sq(sqlist, sqrange, &disj)) != -1)
 229:                 continue;
 230: 
 231:             maxsqcnt = sqcnt;
 232:             vc -= disj;
 233:             if (vc <= 1)
 234:             {
 235:                 De.de_sourcevar = srcvar;
 236:                 qtrue |= decompz(root, qmode, result_num);
 237:                 srcvar = De.de_sourcevar;
 238:             }
 239:             else
 240:             {
 241:                 freebuf(sqbuf, sqmark1);
 242:                 newroot = copy_ands(root, sqbuf);
 243:                 qtrue |= decision(newroot, qmode, result_num, sqbuf);
 244:             }
 245:             vc += disj;
 246:         }
 247:         else
 248:             qtrue |= decompz(root, qmode, result_num);
 249: 
 250:         /* check for early termination on constant Target list */
 251:         if (constl && qtrue)
 252:             break;
 253:     }
 254:     if (j < 0)
 255:         syserr("decompy: bad get %d on %.12s", j, readopen(var)->reldum.relid);
 256: 
 257:     /* undo the effect of pulling the sub queries */
 258:     origvar(root, sqlist);
 259:     undo_sq(sqlist, locrang, sqrange, sqcnt, maxsqcnt, TRUE);
 260: 
 261:     /* undo the setvar on the main tree and all subtrees */
 262:     clearvar(root, var);
 263:     for (j = 0; j < MAXRANGE; j++)
 264:         clearvar(sqlist[j], var);
 265: 
 266:     /* return any used buffer space */
 267:     freebuf(sqbuf, sqmark);
 268: 
 269: #	ifdef xDTR1
 270:     if (tTf(32, 2))
 271:         printf("tc[%.12s]=%d,qtrue=%d\n", rangename(var), tc, qtrue);
 272: #	endif
 273: 
 274:     return (qtrue);
 275: }
 276: /*
 277: **	Decompz processes a one variable query
 278: **	by calling call_ovqp().
 279: **
 280: **	Trace Flags:
 281: **		33
 282: */
 283: 
 284: decompz(q, qmode, result_num)
 285: QTREE   *q;
 286: int qmode;
 287: int result_num;
 288: {
 289:     register QTREE  *root;
 290:     register int    qualfound;
 291: 
 292:     root = q;
 293:     if (root->sym.value.sym_root.tvarc)
 294:     {
 295:         if (De.de_sourcevar < 0)
 296:         {
 297:             if ((De.de_sourcevar = selectv(root)) < 0)
 298:                 return (FALSE);
 299:         }
 300:     }
 301:     else
 302:     {
 303:         De.de_sourcevar = -1;
 304:     }
 305: 
 306:     qualfound = call_ovqp(root, qmode, result_num);
 307:     De.de_newq = 0;
 308:     return (qualfound);
 309: }

Defined functions

decompx defined in line 106; used 1 times
  • in line 73
decompy defined in line 157; used 1 times
decompz defined in line 284; used 4 times
Last modified: 1986-04-17
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