2.11BSD#431 - /usr/ingres/source/dbu/get_seq_atts.c

   1: # include   "../ingres.h"
   2: # include   "../access.h"
   3: 
   4: /*
   5: ** Seq_attributes - get all attributes of a relation in their correct order.
   6: **
   7: **	Seq_attributes() can be called when it is desired to get all
   8: **	attribute tuples for a relation. They are guaranteed to be in
   9: **	the same order as they were created in; that is "attid" order.
  10: **
  11: **	The calling convention is:
  12: **
  13: **		seq_init(Attribute_descriptor, Descriptor_for_relation)
  14: **
  15: **		while (seq_attributes(Att_desc, Des_for_rel, Tuple)
  16: **		{
  17: **		}
  18: **
  19: **	The first parameter is an OPEN descriptor for the attribute
  20: **	relation. The second parameter is a descriptor for the relation.
  21: **	It must have the relation-relation tuple (ie openr mode -1).
  22: **	The third parameter is a place to put the attribute. Its
  23: **	dimension must be at least sizeof (attribute structure).
  24: **
  25: **	Seq_attribute attempts to optimize the retrieval of the
  26: **	attributes. It assumes initially that the are physically
  27: **	stored sequentially. If so it will retrieve them in the
  28: **	minimum possible number of accesses.
  29: **
  30: **	If it finds one tuple out of sequence then all future
  31: **	scans will start from that first out of sequence tuple.
  32: */
  33: 
  34: struct tup_id   Seq_tdl, Seq_tdh, Seq_tdf;
  35: int     Seq_seqmode, Seq_next;
  36: 
  37: 
  38: 
  39: seq_init(atr, rel)
  40: struct descriptor   *atr;
  41: struct descriptor   *rel;
  42: {
  43:     register struct descriptor  *a, *r;
  44:     register int            i;
  45:     struct attribute        attkey;
  46: 
  47:     a = atr;
  48:     r = rel;
  49: 
  50:     clearkeys(a);
  51:     setkey(a, &attkey, r->relid, ATTRELID);
  52:     setkey(a, &attkey, r->relowner, ATTOWNER);
  53:     if (i = find(a, EXACTKEY, &Seq_tdl, &Seq_tdh, &attkey))
  54:         syserr("seq_init:find:%d", i);
  55: 
  56:     Seq_seqmode = TRUE;
  57:     Seq_next = 1;
  58: }
  59: 
  60: 
  61: seq_attributes(atr, rel, att_tuple)
  62: struct descriptor   *atr;
  63: struct descriptor   *rel;
  64: struct attribute    *att_tuple;
  65: {
  66:     register struct descriptor  *a, *r;
  67:     register struct attribute   *atup;
  68:     int             i, nxttup;
  69: 
  70:     a = atr;
  71:     r = rel;
  72:     atup = att_tuple;
  73: 
  74:     if (Seq_next > r->relatts)
  75:         return (0); /* no more attributes */
  76: 
  77:     if (!Seq_seqmode)
  78:     {
  79:         /* attributes not stored sequencially, start from first attribute */
  80:         bmove(&Seq_tdf, &Seq_tdl, sizeof (Seq_tdl));
  81:         nxttup = FALSE;
  82:     }
  83:     else
  84:         nxttup = TRUE;
  85: 
  86:     while ((i = get(a, &Seq_tdl, &Seq_tdh, atup, nxttup)) == 0)
  87:     {
  88: 
  89:         nxttup = TRUE;
  90:         /* make sure this is a tuple for the right relation */
  91:         if (kcompare(a, atup, r))
  92:             continue;
  93: 
  94:         /* is this the attribute we want? */
  95:         if (atup->attid != Seq_next)
  96:         {
  97:             if (Seq_seqmode)
  98:             {
  99:                 /*
 100: 				** Turn off seq mode. Save the tid of
 101: 				** the current tuple. It will be the
 102: 				** starting point for the next call
 103: 				** to seq_attributes
 104: 				*/
 105:                 bmove(&Seq_tdl, &Seq_tdf, sizeof (Seq_tdf));
 106:                 Seq_seqmode = FALSE;
 107:             }
 108: 
 109:             continue;
 110:         }
 111: 
 112:         /* got current attribute. increment to next attribute */
 113:         Seq_next++;
 114:         return (1);
 115:     }
 116: 
 117:     /* fell out of loop. either bad get return or missing attribute */
 118:     syserr("seq_att:bad or missing %d,%d", i, Seq_next);
 119: }

Defined functions

Defined variables