Postgres95 1.01 Distribution - Virgin SourcesPG95-1_01

1 files changed, 336 insertions, 0 deletions

diff --git a/src/backend/commands/_deadcode/version.c b/src/backend/commands/_deadcode/version.c
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+++ b/src/backend/commands/_deadcode/version.c
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+/*-------------------------------------------------------------------------
+ *
+ * version.c--
+ *    This file contains all the rules that govern all version semantics.
+ *
+ * Copyright (c) 1994, Regents of the University of California
+ *
+ *  The version stuff has not been tested under postgres95 and probably doesn't
+ *  work! - jolly 8/19/95
+ *  
+ *
+ * IDENTIFICATION
+ *    $Header: /cvsroot/pgsql/src/backend/commands/_deadcode/Attic/version.c,v 1.1.1.1 1996/07/09 06:21:23 scrappy Exp $
+ *
+ * NOTES
+ *    At the point the version is defined, 2 physical relations are created
+ *    <vname>_added and <vname>_deleted.
+ *
+ *    In addition, 4 rules are defined which govern the semantics of versions 
+ *    w.r.t retrieves, appends, replaces and deletes.
+ *
+ *-------------------------------------------------------------------------
+ */
+#include <stdio.h>
+
+#include "postgres.h"
+
+#include "utils/rel.h"
+#include "access/heapam.h"
+#include "utils/builtins.h"
+#include "utils/elog.h"
+#include "nodes/pg_list.h"
+#include "commands/version.h"
+#include "access/xact.h"		/* for GetCurrentXactStartTime */
+#include "tcop/tcopprot.h"
+
+#define MAX_QUERY_LEN 1024
+
+char rule_buf[MAX_QUERY_LEN];
+static char attr_list[MAX_QUERY_LEN];
+
+static void setAttrList(char *bname);
+
+/*
+ * problem: the version system assumes that the rules it declares will
+ *          be fired in the order of declaration, it also assumes
+ *          goh's silly instead semantics.  Unfortunately, it is a pain
+ *          to make the version system work with the new semantics.
+ *          However the whole problem can be solved, and some nice
+ *          functionality can be achieved if we get multiple action rules
+ *          to work.  So thats what I did                       -- glass
+ *
+ * Well, at least they've been working for about 20 minutes.
+ * 
+ * So any comments in this code about 1 rule per transction are false...:)
+ *
+ */
+
+/*
+ *  This is needed because the rule system only allows 
+ *  *1* rule to be defined per transaction.
+ *
+ * NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
+ * OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
+ * OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
+ * OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
+ * OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
+ * OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
+ * OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
+ * OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
+ * OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
+ * OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
+ * OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
+ * OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
+ * OOOOOOOOOOOOOOOOOOO!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+ *
+ * DONT DO THAT!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+ *
+ * If you commit the current Xact all the palloced memory GOES AWAY
+ * and could be re-palloced in the new Xact and the whole hell breaks
+ * loose and poor people like me spend 2 hours of their live chassing
+ * a strange memory bug instead of watching the "Get Smart" marathon
+ * in NICK !
+ * DO NOT COMMIT THE XACT, just increase the Cid counter!
+ *							_sp.
+ */
+static void
+eval_as_new_xact(char *query)
+{
+    /* WARNING! do not uncomment the following lines WARNING!
+     *  CommitTransactionCommand();
+     * StartTransactionCommand();
+     */
+    CommandCounterIncrement();
+    pg_eval(query, (char **) NULL, (Oid *) NULL, 0);
+}
+
+/*
+ *  Define a version.
+ */
+void
+DefineVersion(char *name, char *fromRelname, char *date)
+{
+    char *bname;
+    static char saved_basename[512];
+    static char saved_snapshot[512];
+
+    if (date == NULL) {
+	/* no time ranges */
+	bname = fromRelname;
+	(void) strcpy(saved_basename, (char *) bname);
+	*saved_snapshot = (char)NULL;
+    } else {
+	/* version is a snapshot */
+	bname = fromRelname;
+	(void) strcpy(saved_basename, (char *) bname);
+	sprintf(saved_snapshot, "['%s']", date);
+    }
+    
+    
+    /*
+     * Calls the routine ``GetAttrList'' get the list of attributes
+     * from the base relation. 
+     * Code is put here so that we only need to look up the attribute once for
+     * both appends and replaces.
+     */
+    setAttrList(bname);
+
+    VersionCreate (name, saved_basename);
+    VersionAppend (name, saved_basename);
+    VersionDelete (name, saved_basename,saved_snapshot);
+    VersionReplace (name, saved_basename,saved_snapshot);
+    VersionRetrieve (name, saved_basename, saved_snapshot);
+}
+
+
+/*
+ *  Creates the deltas.
+ */
+void
+VersionCreate(char *vname, char *bname)
+{
+    static char query_buf [MAX_QUERY_LEN];
+    
+    /*
+     *  Creating the dummy version relation for triggering rules.
+     */
+    sprintf(query_buf, "SELECT * INTO TABLE %s from %s where 1 =2",
+	    vname, bname);
+    
+    pg_eval (query_buf, (char **) NULL, (Oid *) NULL, 0);  
+    
+    /* 
+     * Creating the ``v_added'' relation 
+     */
+    sprintf (query_buf, "SELECT * INTO TABLE %s_added from %s where 1 = 2", 
+	     vname, bname);
+    eval_as_new_xact (query_buf); 
+    
+    /* 
+     * Creating the ``v_deleted'' relation. 
+     */
+    sprintf (query_buf, "CREATE TABLE %s_del (DOID oid)", vname);
+    eval_as_new_xact (query_buf); 
+}
+
+
+/*
+ * Given the relation name, does a catalog lookup for that relation and
+ * sets the global variable 'attr_list' with the list of attributes (names)
+ * for that relation. 
+ */
+static void
+setAttrList(char *bname)
+{
+    Relation rdesc;
+    int i = 0;
+    int maxattrs = 0;
+    char *attrname;
+    char temp_buf[512];
+    int notfirst = 0;    
+
+    rdesc = heap_openr(bname);
+    if (rdesc == NULL ) {
+	elog(WARN,"Unable to expand all -- amopenr failed ");
+	return;
+    }
+    maxattrs = RelationGetNumberOfAttributes(rdesc);
+
+    attr_list[0] = '\0';
+    
+    for ( i = maxattrs-1 ; i > -1 ; --i ) {
+	attrname = (rdesc->rd_att->attrs[i]->attname).data;
+
+	if (notfirst == 1) {
+	    sprintf(temp_buf, ", %s = new.%s", attrname, attrname);
+	} else {
+	    sprintf(temp_buf, "%s = new.%s", attrname, attrname);
+	    notfirst = 1;
+	}
+	strcat(attr_list, temp_buf);  
+    }
+    
+    heap_close(rdesc);
+    
+    return;
+}
+
+/*
+ * This routine defines the rule governing the append semantics of
+ * versions.  All tuples appended to a version gets appended to the 
+ * <vname>_added relation.
+ */
+void
+VersionAppend(char *vname, char *bname)
+{
+    sprintf(rule_buf,
+	    "define rewrite rule %s_append is on INSERT to %s do instead append %s_added(%s)",
+	    vname, vname, vname, attr_list);
+    
+    eval_as_new_xact(rule_buf); 
+}
+
+
+/*
+ * This routine defines the rule governing the retrieval semantics of
+ * versions.  To retrieve tuples from a version , we need to:
+ *
+ *      1. Retrieve all tuples in the <vname>_added relation.
+ *      2. Retrieve all tuples in the base relation which are not in 
+ *         the <vname>_del relation.
+ */
+void
+VersionRetrieve(char *vname, char *bname, char *snapshot)
+{
+    
+    sprintf(rule_buf, 
+	    "define rewrite rule %s_retrieve is on SELECT to %s do instead\n\
+SELECT %s_1.oid, %s_1.* from _%s in %s%s, %s_1 in (%s_added | _%s) \
+where _%s.oid !!= '%s_del.DOID'",
+	    vname, vname, vname, vname, bname,
+	    bname, snapshot,
+	    vname, vname, bname, bname, vname);
+    
+    eval_as_new_xact(rule_buf); 
+    
+    /*  printf("%s\n",rule_buf); */
+    
+}
+
+/*
+ * This routine defines the rules that govern the delete semantics of 
+ * versions. Two things happens when we delete a tuple from a version:
+ *
+ *     1. If the tuple to be deleted was added to the version *after*
+ *        the version was created, then we simply delete the tuple 
+ *        from the <vname>_added relation.
+ *     2. If the tuple to be deleted is actually in the base relation,
+ *        then we have to mark that tuple as being deleted by adding
+ *        it to the <vname>_del relation.
+ */
+void
+VersionDelete(char *vname, char *bname, char *snapshot)
+{
+    
+    sprintf(rule_buf,
+	    "define rewrite rule %s_delete1 is on delete to %s do instead\n \
+[delete %s_added where current.oid = %s_added.oid\n \
+ append %s_del(DOID = current.oid) from _%s in %s%s \
+ where current.oid = _%s.oid] \n",
+	  vname,vname,vname,vname,vname,
+bname,bname,snapshot,bname); 
+
+  eval_as_new_xact(rule_buf); 
+#ifdef OLD_REWRITE
+   sprintf(rule_buf,
+         "define rewrite rule %s_delete2 is on delete to %s do instead \n \
+    append %s_del(DOID = current.oid) from _%s in %s%s \
+    where current.oid = _%s.oid \n",
+         vname,vname,vname,bname,bname,snapshot,bname);
+
+   eval_as_new_xact(rule_buf);
+#endif /*  OLD_REWRITE */
+}
+
+/*
+ *  This routine defines the rules that govern the update semantics
+ *  of versions. To update a tuple in a version:
+ *
+ *      1. If the tuple is in <vname>_added, we simply ``replace''
+ *         the tuple (as per postgres style).
+ *      2. if the tuple is in the base relation, then two things have to
+ *         happen:
+ *         2.1  The tuple is marked ``deleted'' from the base relation by 
+ *              adding the tuple to the <vname>_del relation. 
+ *         2.2  A copy of the tuple is appended to the <vname>_added relation
+ */
+void
+VersionReplace(char *vname, char *bname, char *snapshot)
+{
+    sprintf(rule_buf,
+	    "define rewrite rule %s_replace1 is on replace to %s do instead \n\
+[replace %s_added(%s) where current.oid = %s_added.oid \n\
+ append %s_del(DOID = current.oid) from _%s in %s%s \
+ where current.oid = _%s.oid\n\
+ append %s_added(%s) from _%s in %s%s \
+ where current.oid !!= '%s_added.oid' and current.oid = _%s.oid]\n",
+	  vname,vname,vname,attr_list,vname,
+          vname,bname,bname,snapshot,bname,
+vname,attr_list,bname,bname,snapshot,vname,bname);
+
+  eval_as_new_xact(rule_buf); 
+
+/*  printf("%s\n",rule_buf); */
+#ifdef OLD_REWRITE
+  sprintf(rule_buf,
+	  "define rewrite rule %s_replace2 is on replace to %s do \n\
+    append %s_del(DOID = current.oid) from _%s in %s%s \
+    where current.oid = _%s.oid\n",
+	  vname,vname,vname,bname,bname,snapshot,bname);
+
+  eval_as_new_xact(rule_buf); 
+
+  sprintf(rule_buf,
+	  "define rewrite rule %s_replace3 is on replace to %s do instead\n\
+    append %s_added(%s) from _%s in %s%s \
+    where current.oid !!= '%s_added.oid' and current.oid = \
+    _%s.oid\n",
+	  vname,vname, vname,attr_list,bname,bname,snapshot,vname,bname);
+
+  eval_as_new_xact(rule_buf); 
+#endif /* OLD_REWRITE */
+/*  printf("%s\n",rule_buf); */
+
+}
+