/* * This file contains all the rules that govern all version semantics. * * At the point the version is defined, 2 physical relations are created * _added and _deleted. * * In addition, 4 rules are defined which govern the semantics of versions * w.r.t retrieves, appends, replaces and deletes. * * $Header: /private/postgres/src/commands/RCS/version.c,v 1.16 1992/06/28 03:46:38 mao Exp $ */ #include #include "tmp/postgres.h" #include "utils/rel.h" #include "access/heapam.h" #include "utils/log.h" #include "nodes/pg_lisp.h" #include "commands/version.h" #include "access/xact.h" /* for GetCurrentXactStartTime */ #define MAX_QUERY_LEN 1024 char rule_buf[MAX_QUERY_LEN]; static char attr_list[MAX_QUERY_LEN]; /* * 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. */ void eval_as_new_xact ( query ) char *query; { /* WARNING! do not uncomment the following lines WARNING! * CommitTransactionCommand(); * StartTransactionCommand(); */ CommandCounterIncrement(); pg_eval(query, (char *) NULL, (ObjectId *) NULL, 0); } void CreateVersion (name, bnamestring) Name name; List bnamestring; { LispValue tmp_list = LispNil; int notfirst = 0; int length = 0; char *attrname; LispValue i, temp; Name bname; static char temp_buf[512]; static char saved_basename[512]; static char saved_vname[ sizeof(NameData)]; static char saved_snapshot[512]; if ( NodeType(bnamestring) == classTag(LispStr) ) { /* no time ranges */ bname = (Name)CString(bnamestring); strcpy(saved_basename, bname); *saved_snapshot = (char)NULL; } else { /* version is a snapshot */ bname = (Name)CString(CAR(bnamestring)); strcpy(saved_basename, bname); sprintf(saved_snapshot, "[\"%s\"]", CString(CADR(bnamestring)) ); } bcopy (name, saved_vname, sizeof(NameData)); /* * 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. */ tmp_list = GetAttrList(bname); attr_list[0] = '\0'; foreach(i, tmp_list) { temp = CAR(i); attrname = CString(temp); 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); } length = strlen(attr_list) + 1; VersionCreate ((Name) saved_vname, (Name) saved_basename); VersionAppend ((Name) saved_vname, (Name) saved_basename); VersionDelete ((Name) saved_vname, (Name) saved_basename,saved_snapshot); VersionReplace ((Name) saved_vname, (Name) saved_basename,saved_snapshot); VersionRetrieve ((Name) saved_vname, (Name) saved_basename, saved_snapshot); } void VersionCreate (vname, bname) Name vname; Name bname; { static char query_buf [MAX_QUERY_LEN]; /* * Creating the dummy version relation for triggering rules. */ sprintf(query_buf, "retrieve into %s ( %s.all) where 1 =2", vname,bname); pg_eval (query_buf, (char *) NULL, (ObjectId *) NULL, 0); /* * Creating the ``v_added'' relation */ sprintf (query_buf, "retrieve into %s_added (%s.all) where 1 = 2", vname, bname); eval_as_new_xact (query_buf); /* printf ("%s\n",query_buf); */ /* * Creating the ``v_deleted'' relation. */ sprintf (query_buf, "create %s_del(DOID = oid)", vname); eval_as_new_xact (query_buf); } /* * Given the relation name, GetAttrList does a catalog lookup for that * relation and returns the list of attributes (names) for that relation. */ LispValue GetAttrList(bname) Name bname; { Relation rdesc; int i = 0; int maxattrs = 0; int type_id, type_len,vnum; LispValue attr_list = LispNil; rdesc = heap_openr(bname); if (rdesc == NULL ) { elog(WARN,"Unable to expand all -- amopenr failed "); return(NULL); } maxattrs = RelationGetNumberOfAttributes(rdesc); for ( i = maxattrs-1 ; i > -1 ; --i ) { attr_list = lispCons(lispString((char *)(&rdesc->rd_att.data[i]->attname)), attr_list); } heap_close(rdesc); return(attr_list); } /* * This routine defines the rule governing the append semantics of * versions. All tuples appended to a version gets appended to the * _added relation. */ void VersionAppend (vname,bname) Name vname,bname; { sprintf(rule_buf, "define rewrite rule %s_append is on append to %s do instead append \ %s_added(%s)", vname, vname, vname, attr_list); eval_as_new_xact(rule_buf); /* printf("%s\n",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 _added relation. * 2. Retrieve all tuples in the base relation which are not in * the _del relation. */ void VersionRetrieve(vname,bname,snapshot) Name vname, bname; char *snapshot; { sprintf(rule_buf, "define rewrite rule %s_retrieve is on retrieve to %s do instead\n\ retrieve (%s_1.oid,%s_1.all) 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 _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 _del relation. */ void VersionDelete(vname,bname,snapshot) Name vname,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 _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 _del relation. * 2.2 A copy of the tuple is appended to the _added relation */ void VersionReplace(vname, bname,snapshot) Name vname,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); */ } CreateBVersion(vname,bnamestring) Name vname; List bnamestring; { AbsoluteTime now = NULL; char *timestring = NULL; static char query_buf[MAX_QUERY_LEN]; static char saved_vname[sizeof(NameData)]; static char bname[sizeof(NameData)]; #ifdef BOGUS Name bname; #endif now = GetCurrentTransactionStartTime(); timestring = (char *)abstimeout(now); sprintf(bname,"%s", CString(bnamestring) ); sprintf(saved_vname,"%s", vname); if (NodeType(bnamestring) != classTag(LispStr)) { elog(WARN, "Create Version: Backward deltas of snapshots not supported yet\n"); } /* * Rename the base relation to the version name. */ sprintf(query_buf, "rename %s to %s", bname,vname); eval_as_new_xact(query_buf); /* * Create a dummy base relation from which the * retrieve rule can be triggered. */ sprintf(query_buf, "retrieve into %s(%s.all) where 1 = 2", bname, saved_vname); eval_as_new_xact(query_buf); /* Now to define the retrieve rule. */ sprintf(query_buf,"define rewrite rule b%s_retrieve is \n\ on retrieve to %s do instead retrieve (_%s.all) from _%s in %s[\"%s\"]\n", saved_vname, bname, saved_vname,saved_vname, saved_vname,timestring); eval_as_new_xact(query_buf); }