/*------------------------------------------------------------------------- * * rewriteDefine.c * routines for defining a rewrite rule * * Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION * $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteDefine.c,v 1.29 1999/05/25 16:10:48 momjian Exp $ * *------------------------------------------------------------------------- */ #include #include #include "postgres.h" #include "access/heapam.h" /* access methods like amopenr */ #include "nodes/parsenodes.h" #include "nodes/pg_list.h" /* for Lisp support */ #include "parser/parse_relation.h" #include "rewrite/locks.h" #include "rewrite/rewriteDefine.h" #include "rewrite/rewriteRemove.h" #include "rewrite/rewriteSupport.h" #include "tcop/tcopprot.h" #include "utils/builtins.h" #include "utils/lsyscache.h" /* for get_typlen */ #include "utils/rel.h" /* for Relation stuff */ Oid LastOidProcessed = InvalidOid; /* * This is too small for many rule plans, but it'll have to do for now. * Rule plans, etc will eventually have to be large objects. * * should this be smaller? */ #define RULE_PLAN_SIZE BLCKSZ static void strcpyq(char *dest, char *source) { char *current = source, *destp = dest; for (current = source; *current; current++) { if (*current == '\"') { *destp = '\\'; destp++; } *destp = *current; destp++; } *destp = '\0'; } /* * InsertRule - * takes the arguments and inserts them as attributes into the system * relation "pg_rewrite" * * MODS : changes the value of LastOidProcessed as a side * effect of inserting the rule tuple * * ARGS : rulname - name of the rule * evtype - one of RETRIEVE,REPLACE,DELETE,APPEND * evobj - name of relation * evslot - comma delimited list of slots * if null => multi-attr rule * evinstead - is an instead rule * actiontree - parsetree(s) of rule action */ static Oid InsertRule(char *rulname, int evtype, char *evobj, char *evslot, char *evqual, bool evinstead, char *actiontree) { static char rulebuf[RULE_PLAN_SIZE]; static char actionbuf[RULE_PLAN_SIZE]; static char qualbuf[RULE_PLAN_SIZE]; Oid eventrel_oid = InvalidOid; AttrNumber evslot_index = InvalidAttrNumber; Relation eventrel = NULL; char *is_instead = "f"; extern void eval_as_new_xact(); char *template; eventrel = heap_openr(evobj); if (eventrel == NULL) elog(ERROR, "rules cannot be defined on relations not in schema"); eventrel_oid = RelationGetRelid(eventrel); /* * if the slotname is null, we know that this is a multi-attr rule */ if (evslot == NULL) evslot_index = -1; else evslot_index = attnameAttNum(eventrel, (char *) evslot); heap_close(eventrel); if (evinstead) is_instead = "t"; if (evqual == NULL) evqual = "<>"; if (IsDefinedRewriteRule(rulname)) elog(ERROR, "Attempt to insert rule '%s' failed: already exists", rulname); strcpyq(actionbuf, actiontree); strcpyq(qualbuf, evqual); template = "INSERT INTO pg_rewrite \ (rulename, ev_type, ev_class, ev_attr, ev_action, ev_qual, is_instead) VALUES \ ('%s', %d::char, %u::oid, %d::int2, '%s'::text, '%s'::text, \ '%s'::bool);"; if (strlen(template) + strlen(rulname) + strlen(actionbuf) + strlen(qualbuf) + 20 /* fudge fac */ > RULE_PLAN_SIZE) elog(ERROR, "DefineQueryRewrite: rule plan string too big."); sprintf(rulebuf, template, rulname, evtype, eventrel_oid, evslot_index, actionbuf, qualbuf, is_instead); pg_exec_query_acl_override(rulebuf); return LastOidProcessed; } /* * 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 = NULL; Oid ruleId; Oid ev_relid = 0; char *eslot_string = NULL; int event_attno = 0; Oid event_attype = 0; char *actionP, *event_qualP; List *l; Query *query; /* ---------- * 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 */ if (action != NIL) foreach(l, action) { query = (Query *) lfirst(l); if (query->resultRelation == 1) { elog(NOTICE, "rule actions on OLD currently not supported"); elog(ERROR, " use views or triggers instead"); } if (query->resultRelation == 2) { elog(NOTICE, "rule actions on NEW currently not supported"); elog(ERROR, " use 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(NOTICE, "instead nothing rules on select currently not supported"); elog(ERROR, " use 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, ... */ event_relation = heap_openr(event_obj->relname); if (event_relation == NULL) elog(ERROR, "virtual relations not supported yet"); 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 = nameout(&(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", nameout(&(event_relation->rd_rel->relname))); } } heap_close(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->uniqueFlag != NULL) 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. */ event_relation = heap_openr(event_obj->relname); if (event_relation == NULL) elog(ERROR, "virtual relations not supported yet"); ev_relid = RelationGetRelid(event_relation); if (eslot_string == NULL) { event_attno = -1; event_attype = -1; /* XXX - don't care */ } else { event_attno = attnameAttNum(event_relation, eslot_string); event_attype = attnumTypeId(event_relation, event_attno); } heap_close(event_relation); /* fix bug about instead nothing */ ValidateRule(event_type, event_obj->relname, eslot_string, event_qual, &action, is_instead, event_attype); if (action == NULL) { if (!is_instead) return; /* doesn't do anything */ event_qualP = nodeToString(event_qual); ruleId = InsertRule(stmt->rulename, event_type, event_obj->relname, eslot_string, event_qualP, true, "<>"); prs2_addToRelation(ev_relid, ruleId, event_type, event_attno, TRUE, event_qual, NIL); } else { event_qualP = nodeToString(event_qual); actionP = nodeToString(action); ruleId = InsertRule(stmt->rulename, event_type, event_obj->relname, eslot_string, event_qualP, is_instead, actionP); /* what is the max size of type text? XXX -- glass */ if (length(action) > 15) elog(ERROR, "max # of actions exceeded"); prs2_addToRelation(ev_relid, ruleId, event_type, event_attno, is_instead, event_qual, action); } }