ING_DB
This commit is contained in:
Oliver Lehmann
parent
801ae802cb
commit
a50a43e0c7
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# include <stdio.h>
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# include "gen.h"
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# include "../h/dbs.h"
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# include "../h/aux.h"
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# include "../h/pipes.h"
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# include "../h/symbol.h"
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# include "../h/tree.h"
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# include "parser.h"
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struct pipfrmt Pipebuf; /* define pipe buffer structure
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also referenced in rngsend and treepr */
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/*
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** CALL_TREE -- send a tree to decomp (or qrymod)
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*/
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call_tree(qmode1, execid)
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short qmode1;
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int execid;
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{
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register int qmode;
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register int retr;
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fflush(stdout);
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qmode = qmode1;
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# ifdef xPTR2
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AAtTfp(26, 0, "CALL_TREE: qm=%d\tex=%d\n", qmode, execid);
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# endif
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wrpipe(P_PRIME, &Pipebuf, execid, (char *) 0, qmode);
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writesym(QMODE, sizeof (short), &qmode1);
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if (Resrng)
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{
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# ifdef xPTR2
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AAtTfp(26, 1, "resvarno:%d\n", Resrng->rentno);
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# endif
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writesym(RESULTVAR, sizeof (short), &Resrng->rentno);
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}
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rngsend();
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treepr(Lastree);
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wrpipe(P_END, &Pipebuf, W_down);
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/* optomize test for these two conditions */
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retr = (qmode == (int) mdRETR || qmode == (int) mdRET_UNI);
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/* output sync block to EQL if necessary */
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if (Eql && retr && Resrng == 0)
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syncup();
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syncdn();
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if (retr)
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{
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if (Resrng)
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{
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if (Relspec)
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{
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setp(Resrng->relnm);
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setp(Relspec);
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call_p(mdMODIFY, EXEC_DBU);
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}
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}
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else if (!Eql)
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AAendhdr();
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}
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}
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/*
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** WRITESYM -- does the physical write stuff, etc.
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** for a normal tree symbol. (i.e. other
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** than a SOURCEID--range table entry
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*/
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writesym(typ, len, value)
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register int typ;
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register int len;
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register char *value;
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{
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SYMBOL sym;
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sym.type = typ;
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sym.len = len = ctou(len);
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wrpipe(P_NORM, &Pipebuf, W_down, &sym, TYP_LEN_SIZ);
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if (value)
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wrpipe(P_NORM, &Pipebuf, W_down, value, len);
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}
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/*
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** RNGWRITE -- does the physical write operation, etc.
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** for SOURCEID symbol (i.e. a range table entry).
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*/
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rngwrite(rptr)
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struct rngtab *rptr;
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{
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register SRCID *sp;
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SRCID s;
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sp = &s;
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((SYMBOL *) sp)->type = SOURCEID;
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((SYMBOL *) sp)->len = SRC_SIZ;
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sp->srcvar = rptr->rentno;
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AApmove(rptr->relnm, sp->srcname, MAXNAME, ' ');
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AAbmove(rptr->relnowner, sp->srcown, 2);
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sp->srcstat = rptr->rstat;
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wrpipe(P_NORM, &Pipebuf, W_down, sp, TYP_LEN_SIZ);
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wrpipe(P_NORM, &Pipebuf, W_down, &sp->srcvar, SRC_SIZ);
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# ifdef xPTR3
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AAtTfp(26, 2, "srcvar:%d\tsrcname:%.12s\tsrcown:%.2s\tsrcstat:0%o\n",
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sp->srcvar, sp->srcname, sp->srcown, sp->srcstat);
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# endif
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}
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@ -0,0 +1,373 @@
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# include "gen.h"
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# include "../h/dbs.h"
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# include "../h/aux.h"
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# include "../h/symbol.h"
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# include "../h/tree.h"
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# include "qrymod.h"
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/*
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** VIEW.C -- view processing
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**
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** This module does the view processing. Basically, it operates
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** by detecting all references to views and replacing them by
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** references to real relations. There are a number of cases
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** when it cannot do this, to whit:
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**
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** Syntactic problems: the view may have a domain defined as
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** a non-simple value (that is, not a simple attribute), which
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** is then required to take on a value. For example, if the
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** view is defined as
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** range of x is baserel
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** define v (d = x.a / 3)
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** and then referenced as
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** append to v (d = 7)
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** would result after query modification as
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** range of x is baserel
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** append to baserel (a / 3 = 7)
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** which is not acceptable. Of course, there is a range of cases
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** where this can be fixed, but (for the time being) we will just
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** throw them all out.
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**
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** Disappearing tuple anomaly: the implicit qualification on
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** a view allows tuples to disappear even when not a duplicate.
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** For example, take a view defined as:
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** range of x is baserel
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** define v (d = x.a) where x.a = 4
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** and issue the query
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** append to v (d = 5)
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** The tuple will be inserted into the base relation, but will not
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** be included in the view. To solve that problem, we disallow
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** updates to domains included in the qualification of the query.
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** Note that this includes implicit updates, that is, an append
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** with the domain missing (which implicitly appends a zero or
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** blank domain).
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**
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** Cross product problem: a view which is defined as a cross
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** product of two relations has several update anomalies. For
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** example, take R1 and R2 as:
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** R1 | a | b R2 | b | c
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** ---|---|--- ---|---|---
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** | 7 | 0 | 0 | 3
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** | 8 | 0 | 0 | 4
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** and issue the view definition
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** range of m is R1
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** range of n is R2
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** define v (m.a, m.b, n.c) where m.b = n.b
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** which will define a view which looks like
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** view | a | b | c
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** -----|---|---|---
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** | 7 | 0 | 3
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** | 7 | 0 | 4
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** | 8 | 0 | 3
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** | 8 | 0 | 4
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** Now try issuing
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** range of v is v
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** delete v where v.a = 8 and v.c = 4
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** which will try to give a view which looks like:
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** view | a | b | c
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** -----|---|---|---
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** | 7 | 0 | 3
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** | 7 | 0 | 4
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** | 8 | 0 | 3
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** which is of course unexpressible in R1 and R2.
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**
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** Multiple query problem: certain updates will require gener-
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** ating multiple queries to satisfy the update on the view.
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** Although this can be made to work, it won't now. Cases are
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** replaces where the target list contains more than one
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** relation, and appends to a view over more than one relation.
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**
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** To solve these problems, we dissallow the following cases:
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**
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** I. In a REPLACE or APPEND statement, if a 'v.d' appears
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** on the LHS in the target list of the query and
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** the a-fcn for 'v.d' is not a simple attribute.
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** II. In REPLACE or APPEND statements, if a 'v.d' appears
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** on the LHS in a target list of the query and in
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** the qualification of the view.
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** III. In a DELETE or APPEND statement, if the view ranges
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** over more than one relation.
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** IV. In a REPLACE statement, if the query resulting after
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** modification of the tree, but before appending the
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** view qualification Qv, has more than one variable.
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** V. In any update, if an aggregate or aggregate function
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** appears anywhere in the target list of the view.
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**
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** Note the assumption that the definition of a consistant update
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** is:
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** "An update is consistant if the result of
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** performing the update on the view and then
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** materializing that view is the same as the
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** result of materializing the view and then
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** performing the update."
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**
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** Defines:
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** view -- the driver for the view algorithm.
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** vrscan -- to scan the query tree and substitute
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** RESDOM nodes (plus much validity checking).
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** Newresvar -- the new 'Resultvar' on updates.
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*/
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int Newresvar; /* new result variable, becomes Resultvar */
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/*
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** VIEW -- driver for view processing
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**
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** This routine does the view processing portion of qrymod.
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** Since the AA_TREE catalog can contain relations which are
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** themselves views, it iterates over itself until no views
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** are found. Presumably this cannot result in an infinite
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** loop, although in fact it probably can; this should be
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** dealt with at some time.
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**
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** For each range variable declared, it is checked whether
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** that variable is a view. If not, it is ignored.
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** Then the tree which defines
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** this view is fetched from the AA_TREE catalog by 'gettree',
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** which also defines any variables required by this tree
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** and adjusts the tree so that the varno's contained in the
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** tree correspond to the varno's in the range table.
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**
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** 'Subsvars' and 'vrscan' really do it. Given the root of the tree
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** to be modified, the variable number to be eliminated, and the
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** target list for a replacement tree, they actually do the
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** tacking of 'new tree' onto 'old tree'. After it is done,
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** there should be no references to the old variable at all
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** in the tree. 'Subsvars' scans for VAR nodes (which are
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** retrieve-only, and hence are always alright); 'vrscan' scans
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** the left hand branch of the tree (the RESDOM nodes) and
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** substitutes them.
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**
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** 'Appqual' appends the qualification for the view (if any)
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** onto the tree. Finally, the variable for the view (which
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** had all references to it eliminated by 'subsvars') is un-
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** defined, so that that slot in the range table can be re-
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** used by later scans.
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**
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** Parameters:
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** root -- root of the tree to be modified.
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**
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** Returns:
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** Root of modified tree.
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**
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** Side Effects:
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** The range table is updated to delete any views and
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** add any base relations needed to support them.
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** Activity occurs in the AA_TREE catalog to get the trees
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** needed to define the views.
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** The tree pointed to by 'root' is modified.
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*/
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QTREE *view(root)
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QTREE *root;
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{
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register int vn;
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register QTREE *vtree;
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int viewfound;
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extern QTREE *gettree();
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QTREE *r;
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extern QTREE *norml();
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# ifdef xQTR1
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AAtTfp(30, -1, "VIEW\n");
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# endif
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r = root;
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/* scan range table until no views */
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viewfound = TRUE;
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while (viewfound)
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{
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# ifdef xQTR2
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AAtTfp(30, 1, "scanning Rangev\n");
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# endif
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/* scan range table for views */
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viewfound = FALSE;
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/* make new resultvar old resultvar for non-update */
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Newresvar = Resultvar;
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/* scan all variables in range table */
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for (vn = 0; vn < MAXVAR + 1; vn++)
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{
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/* check for empty entry in range table */
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if (!Rangev[vn].rused)
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continue;
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/* see if it is a view or base relation */
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if ((Rangev[vn].rstat & S_VIEW) == 0)
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continue;
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# ifdef xQTR1
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AAtTfp(30, 3, "VIEW: vn %d: %.12s\n", vn, Rangev[vn].relid);
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# endif
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vtree = gettree(Rangev[vn].relid, Rangev[vn].rowner, mdVIEW, 0, FALSE);
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# ifdef xQTR3
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if (AAtTf(30, 5))
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treepr(vtree, "Viewdef");
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# endif
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/* check for updating with aggregates */
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if (Qmode != (int) mdRETR && aggcheck(vtree))
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far_error(3350, Qmode, Resultvar, (char *) 0); /* cannot update views with aggregates */
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/* scan view replacing RESDOM nodes */
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if (Qmode != (int) mdRETR && vn == Resultvar)
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vrscan(&r->left, vtree);
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/* scan view replacing VAR nodes */
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subsvars(&r, vn, vtree->left, mdVIEW);
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/* test for non-functional replace */
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if (Qmode == (int) mdREPL && bitcnt(varset(r) | (1 << Newresvar)) > 1)
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far_error(3360, Qmode, Resultvar, (char *) 0); /* non-functional update */
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/* append new qualification */
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appqual(vtree->right, r);
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/* delete view range variable */
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Rangev[vn].rused = FALSE;
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/* mark the view as having been processed */
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viewfound = TRUE;
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/* change 'Resultvar' to be the base rel var */
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Resultvar = Newresvar;
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}
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}
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/* renormalize the tree (just in case) */
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r->right = norml(trimqlend(r->right));
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# ifdef xQTR1
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if (AAtTf(30, 15))
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treepr(r, "VIEW->");
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# endif
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return (r);
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}
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/*
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** VRSCAN -- scan query tree and replace RESDOM nodes
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**
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** The query tree issued is scanned and RESDOM nodes are
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** converted to conform to the underlying base relations.
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** There are many checks in here, and things can fail
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** easily.
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**
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** The first check is for more than one relation in a
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** DELETE or APPEND command. This would require expanding
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** the query into at least two queries. For DELETE commands,
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** this is the only check. (Note that by this time 'aggcheck'
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** has aborted anything which would cause problems with
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** aggregates.)
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**
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** For append commands, we abort immediately if there is
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** a qualification on the view, since the inserted tuple(s)
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** might not (all) appear in the view.
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**
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** For all other queries, the target list of the query submitted
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** is scanned down the left hand side (the RESDOM list).
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** For each RESDOM, that variable is looked up in the view
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** definition. If the definition of it is not a simple
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** attribute, the query is aborted.
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**
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** Then, if the variable appears anywhere in the qualification
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** of the view, the query is aborted.
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**
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** Finally, we keep track of the varno which should become the
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** new number two (that is, the Resultvar). If there are two
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** candidates for this position, we promptly abort.
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**
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** And as the last step, we actually change the 'resno' for
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** this RESDOM.
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**
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** When we exit the loop which scans RESDOM's, we change the
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** 'Resultvar' to be the new variable which we have selected.
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**
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** Notice that there are a number of overly restrictive
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** conditions on runability. Notably, there are large classes
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** of queries which can run consistantly but which violate
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** either the not-in-qualification condition or the aggregate-
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** free condition.
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**
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** Parameters:
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** root -- the root of the tree to be updated.
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** vtree -- the tree which defines the view.
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**
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** Side Effects:
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** The tree pointed to by 'root' is modified.
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*/
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vrscan(root, vtree)
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QTREE *root;
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QTREE *vtree;
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{
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register QTREE *t;
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register QTREE *v;
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int i;
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extern QTREE *qscan();
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extern QTREE *vfind();
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register QTREE *p;
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t = root;
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v = vtree;
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/* check DELETE and APPEND cases of > 1 relation */
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if (Qmode == (int) mdDEL || Qmode == (int) mdAPP)
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{
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/* scan target list of view for > 1 relation */
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if (bitcnt(i = varset(v->left)) != 1)
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far_error(3330, Qmode, Resultvar, (char *) 0); /* query would result in > 1 query */
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/* this is the only check in this module for DELETES */
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if (Qmode == (int) mdDEL)
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{
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/* set Resultvar to underlying (single) relation */
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Newresvar = bitpos(i);
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return;
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}
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/* check for a qualification on an append */
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if (v->right->sym.type != QLEND)
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far_error(3320, Qmode, Resultvar, (char *) 0); /* attribute in qualification of view */
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}
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/* scan target list of query */
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i = -1;
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while ((t = t->left)->sym.type != TREE)
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{
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if (t->sym.type != RESDOM)
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AAsyserr(19063, t->sym.type);
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/* check for 'tid' attribute (stuck in by DEL and REPL) */
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if (((RES_NODE *) t)->resno == 0)
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{
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continue;
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}
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/* find definition for this domain in the view */
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p = vfind(((RES_NODE *) t)->resno, v->left);
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/* check for simple attribute */
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if (p->sym.type != VAR)
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far_error(3310, Qmode, Resultvar, (char *) 0); /* non-simple attribute */
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/* scan qualification of view for this attribute */
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if (qscan(v->right, ((VAR_NODE *) p)->varno, ((VAR_NODE *) p)->attno) != (QTREE *) 0)
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far_error(3320, Qmode, Resultvar, (char *) 0); /* attribute in qualification of view */
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/* check for trying to do update on two relations again */
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/* this test should only be true for REPLACE commands */
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if (i < 0)
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i = ((VAR_NODE *) p)->varno;
|
||||
else if (i != ((VAR_NODE *) p)->varno)
|
||||
far_error(3330, Qmode, Resultvar, (char *) 0); /* query on two relations */
|
||||
|
||||
/* finally, do the substitution of resno's */
|
||||
((RES_NODE *) t)->resno = ((VAR_NODE *) p)->attno;
|
||||
}
|
||||
|
||||
/* change the result variable for the query to the underlying */
|
||||
Newresvar = i;
|
||||
}
|
||||
|
|
@ -0,0 +1,19 @@
|
|||
# include <stdio.h>
|
||||
# include "../conf/gen.h"
|
||||
|
||||
|
||||
main()
|
||||
{
|
||||
register int c;
|
||||
# ifdef SETBUF
|
||||
char ibuf[BUFSIZ];
|
||||
char obuf[BUFSIZ];
|
||||
|
||||
setbuf(stdin, ibuf);
|
||||
setbuf(stdout, obuf);
|
||||
# endif
|
||||
|
||||
while ((c = getchar()) >= 0)
|
||||
AAxputchar(c);
|
||||
putchar('\n');
|
||||
}
|
||||
Loading…
Reference in New Issue