Complete Linux/Complete Linux.iso/docs/apps/database/ingres04.lzh/source/qrymod/integrity.c

C/C++ Source or Header | 1988-05-30 | 4.1 KB | 197 lines

# include    <ingres.h>
# include    <aux.h>
# include    <catalog.h>
# include    <access.h>
# include    <tree.h>
# include    <symbol.h>
# include    "qrymod.h"
# include    <sccs.h>

SCCSID(@(#)integrity.c    8.4    5/30/88)

/*
**  INTEGRITY.C -- Integrity Constraint Processor
**
**    This module contains the integrity constraint processor.  This
**    processor modifies the query to add integrity constraints.
**
**    Currently only single-variable aggregate-free constraints are
**    handled.  Thus the algorithm is reduced to scanning the tree
**    for each variable modified and appending the constraints for
**    that variable to the tree.
**
**    Parameters:
**        none
**
**    Returns:
**        The root of the modified tree.
**
**    Side Effects:
**        Much relation I/O.
**        Modifies the tree in place, so the previous one is
**            lost.
**
**    Trace Flags:
**        40 -> 49
*/

extern DESC    Intdes;

QTREE *
integrity(root)
QTREE    *root;
{
    register QTREE        *r;
    short            dset[8];
    register QTREE        *p;
    register int        i;
    auto QTREE        *iqual;
    struct integrity    inttup, intkey;
    struct tup_id        hitid, lotid;
    extern QTREE        *gettree();
    extern QTREE        *norml();

#    ifdef xQTR1
    tTfp(40, -1, "\n->INTEGRITY\n");
#    endif

    r = root;

    /*
    **  Check to see if we should apply the integrity
    **  algorithm.
    **
    **  This means checking to insure that we have an update
    **  and seeing if any integrity constraints apply.
    */

    if (Qt.qt_qmode == mdRETR || Qt.qt_qmode == mdRET_UNI ||
        (Qt.qt_rangev[Qt.qt_resvar].rngvdesc->reldum.relstat & S_INTEG) == 0)
    {
#        ifdef xQTR2
        tTfp(40, 0, "->INTEGRITY: no integ\n");
#        endif
        return(r);
    }

    /*
    **  Create a set of the domains updated in this query.
    */

    for (i = 0; i < 8; i++)
        dset[i] = 0;
    for (p = r->left; p != NULL && p->sym.type != TREE; p = p->left)
    {
#        ifdef xQTR3
        if (p->sym.type != RESDOM)
            syserr("integrity: RESDOM %d", p->sym.type);
#        endif
        lsetbit(p->sym.value.sym_resdom.resno, dset);
    }

#    ifdef xQTR3
    if (p == NULL)
        syserr("integrity: NULL LHS");
#    endif
#    ifdef xQTR1
    if (tTf(40, 1))
        pr_set(dset, "dset");
#    endif

    /*
    **  Scan integrity catalog for possible tuples.  If found,
    **  include them in the integrity qualification.
    */

    iqual = NULL;
    opencatalog("integrities", OR_READ);
    setkey(&Intdes, &intkey, Qt.qt_rangev[Qt.qt_resvar].rngvdesc->reldum.relid, INTRELID);
    setkey(&Intdes, &intkey, Qt.qt_rangev[Qt.qt_resvar].rngvdesc->reldum.relowner, INTRELOWNER);
    find(&Intdes, EXACTKEY, &lotid, &hitid, &intkey);

    while ((i = get(&Intdes, &lotid, &hitid, &inttup, TRUE)) == 0)
    {
        if (kcompare(&Intdes, &intkey, &inttup) != 0)
            continue;

#        ifdef xQTR1
        if (tTf(40, 2)) {
            printup(&Intdes, &inttup);
            pr_set(inttup.intdomset, "tset");
        }
#        endif

        /* check for some domain set overlap */
        for (i = 0; i < 8; i++)
            if ((dset[i] & inttup.intdomset[i]) != 0)
                break;

        if (i >= 8)
            continue;

        /* some domain matches, include in integrity qual */
        i = Qt.qt_resvar;
        p = gettree(Qt.qt_rangev[i].rngvdesc->reldum.relid,
                Qt.qt_rangev[i].rngvdesc->reldum.relowner,
                mdINTEG, inttup.inttree, FALSE);
#        ifdef xQTR1
        if (tTf(40, 3))
            treeprn(p, "int_qual");
#        endif

        /* trim off (null) target list */
        p = p->right;

        /* merge the 'integrity' var into the Qt.qt_resvar */
        i = inttup.intresvar;
        if (Qt.qt_remap[i] >= 0)
            i = Qt.qt_remap[i];
        mergevar(i, Qt.qt_resvar, p);

        /* add to integrity qual */
        if (iqual == NULL)
            iqual = p;
        else
            appqual(p, iqual);
    }
    if (i < 0)
        syserr("integrity: get %d", i);

    /*
    **  Clean up the integrity qualification so that it will merge
    **  nicely into the tree, and then append it to the user's
    **  qualification.
    */

    if (iqual != NULL)
    {
        /* replace VAR nodes by corresponding user afcn */
        subsvars(&iqual, Qt.qt_resvar, r->left, Qt.qt_qmode);

        /* append to tree and normalize */
        appqual(iqual, r);
#        ifdef xQTR3
        if (tTf(40, 8))
            treeprn(r, "Unnormalized tree");
#        endif
        r->right = norml(trimqlend(r->right));
    }

#    ifdef xQTR1
    if (tTf(40, 15))
        treeprn(r, "INTEGRITY->");
#    endif

    return (r);
}

# ifdef xQTR1
treeprn(p, str)
QTREE    *p;
char    *str;
{
  printf("%s\n", str);
  treepr(p);
}
# endif