/*------------------------------------------------------------------------- * * rewriteDefine.c * routines for defining a rewrite rule * * Portions Copyright (c) 1996-2000, PostgreSQL, Inc * Portions Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION * $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteDefine.c,v 1.48 2000/06/30 07:04:22 tgl Exp $ * *------------------------------------------------------------------------- */ #include "postgres.h" #include "access/heapam.h" #include "utils/builtins.h" #include "catalog/catname.h" #include "catalog/indexing.h" #include "catalog/pg_rewrite.h" #include "parser/parse_relation.h" #include "rewrite/rewriteDefine.h" #include "rewrite/rewriteSupport.h" /* * InsertRule - * takes the arguments and inserts them as attributes into the system * relation "pg_rewrite" */ static Oid InsertRule(char *rulname, int evtype, Oid eventrel_oid, AttrNumber evslot_index, bool evinstead, char *evqual, char *actiontree) { int i; Datum values[Natts_pg_rewrite]; char nulls[Natts_pg_rewrite]; NameData rname; Relation pg_rewrite_desc; TupleDesc tupDesc; HeapTuple tup; Oid rewriteObjectId; if (IsDefinedRewriteRule(rulname)) elog(ERROR, "Attempt to insert rule '%s' failed: already exists", rulname); /* ---------------- * Set up *nulls and *values arrays * ---------------- */ MemSet(nulls, ' ', sizeof(nulls)); i = 0; namestrcpy(&rname, rulname); values[i++] = NameGetDatum(&rname); values[i++] = CharGetDatum(evtype + '0'); values[i++] = ObjectIdGetDatum(eventrel_oid); values[i++] = Int16GetDatum(evslot_index); values[i++] = BoolGetDatum(evinstead); values[i++] = PointerGetDatum(lztextin(evqual)); values[i++] = PointerGetDatum(lztextin(actiontree)); /* ---------------- * create a new pg_rewrite tuple * ---------------- */ pg_rewrite_desc = heap_openr(RewriteRelationName, RowExclusiveLock); tupDesc = pg_rewrite_desc->rd_att; tup = heap_formtuple(tupDesc, values, nulls); heap_insert(pg_rewrite_desc, tup); rewriteObjectId = tup->t_data->t_oid; if (RelationGetForm(pg_rewrite_desc)->relhasindex) { Relation idescs[Num_pg_rewrite_indices]; CatalogOpenIndices(Num_pg_rewrite_indices, Name_pg_rewrite_indices, idescs); CatalogIndexInsert(idescs, Num_pg_rewrite_indices, pg_rewrite_desc, tup); CatalogCloseIndices(Num_pg_rewrite_indices, idescs); } heap_freetuple(tup); heap_close(pg_rewrite_desc, RowExclusiveLock); return rewriteObjectId; } /* * for now, event_object must be a single attribute */ static void ValidateRule(int event_type, char *eobj_string, char *eslot_string, Node *event_qual, List **action, int is_instead, Oid event_attype) { if (((event_type == CMD_INSERT) || (event_type == CMD_DELETE)) && eslot_string) { elog(ERROR, "rules not allowed for insert or delete events to an attribute"); } #ifdef NOT_USED /* * on retrieve to class.attribute do instead nothing is converted to * 'on retrieve to class.attribute do instead retrieve (attribute = * NULL)' --- this is also a terrible hack that works well -- glass */ if (is_instead && !*action && eslot_string && event_type == CMD_SELECT) { char *temp_buffer = (char *) palloc(strlen(template) + 80); sprintf(temp_buffer, template, event_attype, get_typlen(event_attype), eslot_string, event_attype); *action = (List *) stringToNode(temp_buffer); pfree(temp_buffer); } #endif } void DefineQueryRewrite(RuleStmt *stmt) { CmdType event_type = stmt->event; Attr *event_obj = stmt->object; Node *event_qual = stmt->whereClause; bool is_instead = stmt->instead; List *action = stmt->actions; Relation event_relation; Oid ev_relid; Oid ruleId; char *eslot_string = NULL; int event_attno; Oid event_attype; char *actionP, *event_qualP; List *l; Query *query; /* * If we are installing an ON SELECT rule, we had better grab * AccessExclusiveLock to ensure no SELECTs are currently running on * the event relation. For other types of rules, it might be sufficient * to grab ShareLock to lock out insert/update/delete actions. But * for now, let's just grab AccessExclusiveLock all the time. */ event_relation = heap_openr(event_obj->relname, AccessExclusiveLock); ev_relid = RelationGetRelid(event_relation); /* ---------- * The current rewrite handler is known to work on relation level * rules only. And for SELECT events, it expects one non-nothing * action that is instead and returns exactly a tuple of the * rewritten relation. This restricts SELECT rules to views. * * Jan * ---------- */ if (event_obj->attrs) elog(ERROR, "attribute level rules currently not supported"); /* * eslot_string = strVal(lfirst(event_obj->attrs)); */ else eslot_string = NULL; /* * No rule actions that modify OLD or NEW */ foreach(l, action) { query = (Query *) lfirst(l); if (query->resultRelation == 1) { elog(ERROR, "rule actions on OLD currently not supported" "\n\tuse views or triggers instead"); } if (query->resultRelation == 2) { elog(ERROR, "rule actions on NEW currently not supported" "\n\tuse triggers instead"); } } /* * Rules ON SELECT are restricted to view definitions */ if (event_type == CMD_SELECT) { TargetEntry *tle; Resdom *resdom; Form_pg_attribute attr; char *attname; int i; char expected_name[NAMEDATALEN + 5]; /* * So there cannot be INSTEAD NOTHING, ... */ if (length(action) == 0) { elog(ERROR, "instead nothing rules on select currently not supported" "\n\tuse views instead"); } /* * ... there cannot be multiple actions, ... */ if (length(action) > 1) elog(ERROR, "multiple action rules on select currently not supported"); /* * ... the one action must be a SELECT, ... */ query = (Query *) lfirst(action); if (!is_instead || query->commandType != CMD_SELECT) elog(ERROR, "only instead-select rules currently supported on select"); if (event_qual != NULL) elog(ERROR, "event qualifications not supported for rules on select"); /* * ... the targetlist of the SELECT action must exactly match the * event relation, ... */ if (event_relation->rd_att->natts != length(query->targetList)) elog(ERROR, "select rules target list must match event relations structure"); for (i = 1; i <= event_relation->rd_att->natts; i++) { tle = (TargetEntry *) nth(i - 1, query->targetList); resdom = tle->resdom; attr = event_relation->rd_att->attrs[i - 1]; attname = NameStr(attr->attname); if (strcmp(resdom->resname, attname) != 0) elog(ERROR, "select rules target entry %d has different column name from %s", i, attname); if (attr->atttypid != resdom->restype) elog(ERROR, "select rules target entry %d has different type from attribute %s", i, attname); if (attr->atttypmod != resdom->restypmod) elog(ERROR, "select rules target entry %d has different size from attribute %s", i, attname); } /* * ... there must not be another ON SELECT rule already ... */ if (event_relation->rd_rules != NULL) { for (i = 0; i < event_relation->rd_rules->numLocks; i++) { RewriteRule *rule; rule = event_relation->rd_rules->rules[i]; if (rule->event == CMD_SELECT) elog(ERROR, "%s is already a view", RelationGetRelationName(event_relation)); } } /* * LIMIT in view is not supported */ if (query->limitOffset != NULL || query->limitCount != NULL) elog(ERROR, "LIMIT clause not supported in views"); /* * DISTINCT on view is not supported */ if (query->distinctClause != NIL) elog(ERROR, "DISTINCT not supported in views"); /* * ORDER BY in view is not supported */ if (query->sortClause != NIL) elog(ERROR, "ORDER BY not supported in views"); /* * ... and finally the rule must be named _RETviewname. */ sprintf(expected_name, "_RET%s", event_obj->relname); if (strcmp(expected_name, stmt->rulename) != 0) { elog(ERROR, "view rule for %s must be named %s", event_obj->relname, expected_name); } } /* * This rule is allowed - install it. */ if (eslot_string == NULL) { event_attno = -1; event_attype = InvalidOid; } else { event_attno = attnameAttNum(event_relation, eslot_string); event_attype = attnumTypeId(event_relation, event_attno); } /* fix bug about instead nothing */ ValidateRule(event_type, event_obj->relname, eslot_string, event_qual, &action, is_instead, event_attype); /* discard rule if it's null action and not INSTEAD; it's a no-op */ if (action != NULL || is_instead) { event_qualP = nodeToString(event_qual); actionP = nodeToString(action); ruleId = InsertRule(stmt->rulename, event_type, ev_relid, event_attno, is_instead, event_qualP, actionP); /* * Set pg_class 'relhasrules' field TRUE for event relation. * * Important side effect: an SI notice is broadcast to force all * backends (including me!) to update relcache entries with the new * rule. */ setRelhasrulesInRelation(ev_relid, true); } /* Close rel, but keep lock till commit... */ heap_close(event_relation, NoLock); }