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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); */
+
+}
+
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