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Annotation of pgsql/src/backend/rewrite/rewriteHandler.c, revision 1.169
1.1 scrappy 1: /*------------------------------------------------------------------------- 2: * 1.35 momjian 3: * rewriteHandler.c 1.95 tgl 4: * Primary module of query rewriter. 1.1 scrappy 5: * 1.169 ! momjian 6: * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group 1.66 momjian 7: * Portions Copyright (c) 1994, Regents of the University of California 1.1 scrappy 8: * 9: * IDENTIFICATION 1.169 ! momjian 10: * $PostgreSQL: pgsql/src/backend/rewrite/rewriteHandler.c,v 1.168 2006/10/06 17:13:59 petere Exp $ 1.1 scrappy 11: * 12: *------------------------------------------------------------------------- 13: */ 14: #include "postgres.h" 1.53 momjian 15: 16: #include "access/heapam.h" 17: #include "catalog/pg_type.h" 1.55 tgl 18: #include "nodes/makefuncs.h" 1.47 tgl 19: #include "optimizer/clauses.h" 1.53 momjian 20: #include "parser/analyze.h" 1.101 tgl 21: #include "parser/parse_coerce.h" 1.55 tgl 22: #include "parser/parse_expr.h" 1.53 momjian 23: #include "parser/parsetree.h" 1.95 tgl 24: #include "rewrite/rewriteHandler.h" 1.1 scrappy 25: #include "rewrite/rewriteManip.h" 1.101 tgl 26: #include "utils/builtins.h" 1.22 momjian 27: #include "utils/lsyscache.h" 28: 29: 1.118 tgl 30: /* We use a list of these to detect recursion in RewriteQuery */ 1.126 momjian 31: typedef struct rewrite_event 32: { 1.118 tgl 33: Oid relation; /* OID of relation having rules */ 34: CmdType event; /* type of rule being fired */ 1.128 momjian 35: } rewrite_event; 1.118 tgl 36: 1.153 tgl 37: static bool acquireLocksOnSubLinks(Node *node, void *context); 1.95 tgl 38: static Query *rewriteRuleAction(Query *parsetree, 1.98 momjian 39: Query *rule_action, 40: Node *rule_qual, 41: int rt_index, 1.166 tgl 42: CmdType event, 43: bool *returning_flag); 1.89 tgl 44: static List *adjustJoinTreeList(Query *parsetree, bool removert, int rt_index); 1.165 joe 45: static void rewriteTargetList(Query *parsetree, Relation target_relation, 1.167 momjian 46: List **attrno_list); 1.101 tgl 47: static TargetEntry *process_matched_tle(TargetEntry *src_tle, 1.144 momjian 48: TargetEntry *prior_tle, 49: const char *attrName); 1.139 tgl 50: static Node *get_assignment_input(Node *node); 1.165 joe 51: static void rewriteValuesRTE(RangeTblEntry *rte, Relation target_relation, 1.167 momjian 52: List *attrnos); 1.157 tgl 53: static void markQueryForLocking(Query *qry, bool forUpdate, bool noWait, 1.158 momjian 54: bool skipOldNew); 1.81 tgl 55: static List *matchLocks(CmdType event, RuleLock *rulelocks, 1.90 momjian 56: int varno, Query *parsetree); 1.118 tgl 57: static Query *fireRIRrules(Query *parsetree, List *activeRIRs); 1.82 tgl 58: 1.1 scrappy 59: 60: /* 1.153 tgl 61: * AcquireRewriteLocks - 62: * Acquire suitable locks on all the relations mentioned in the Query. 63: * These locks will ensure that the relation schemas don't change under us 64: * while we are rewriting and planning the query. 65: * 66: * A secondary purpose of this routine is to fix up JOIN RTE references to 67: * dropped columns (see details below). Because the RTEs are modified in 68: * place, it is generally appropriate for the caller of this routine to have 69: * first done a copyObject() to make a writable copy of the querytree in the 70: * current memory context. 71: * 72: * This processing can, and for efficiency's sake should, be skipped when the 73: * querytree has just been built by the parser: parse analysis already got 74: * all the same locks we'd get here, and the parser will have omitted dropped 75: * columns from JOINs to begin with. But we must do this whenever we are 76: * dealing with a querytree produced earlier than the current command. 77: * 78: * About JOINs and dropped columns: although the parser never includes an 79: * already-dropped column in a JOIN RTE's alias var list, it is possible for 80: * such a list in a stored rule to include references to dropped columns. 81: * (If the column is not explicitly referenced anywhere else in the query, 82: * the dependency mechanism won't consider it used by the rule and so won't 83: * prevent the column drop.) To support get_rte_attribute_is_dropped(), 84: * we replace join alias vars that reference dropped columns with NULL Const 85: * nodes. 86: * 87: * (In PostgreSQL 8.0, we did not do this processing but instead had 88: * get_rte_attribute_is_dropped() recurse to detect dropped columns in joins. 89: * That approach had horrible performance unfortunately; in particular 90: * construction of a nested join was O(N^2) in the nesting depth.) 91: */ 92: void 93: AcquireRewriteLocks(Query *parsetree) 94: { 95: ListCell *l; 96: int rt_index; 97: 98: /* 99: * First, process RTEs of the current query level. 100: */ 101: rt_index = 0; 102: foreach(l, parsetree->rtable) 103: { 104: RangeTblEntry *rte = (RangeTblEntry *) lfirst(l); 105: Relation rel; 106: LOCKMODE lockmode; 107: List *newaliasvars; 1.154 tgl 108: Index curinputvarno; 109: RangeTblEntry *curinputrte; 1.153 tgl 110: ListCell *ll; 111: 112: ++rt_index; 113: switch (rte->rtekind) 114: { 115: case RTE_RELATION: 1.158 momjian 116: 1.153 tgl 117: /* 1.158 momjian 118: * Grab the appropriate lock type for the relation, and do not 119: * release it until end of transaction. This protects the 120: * rewriter and planner against schema changes mid-query. 1.153 tgl 121: * 1.159 momjian 122: * If the relation is the query's result relation, then we 123: * need RowExclusiveLock. Otherwise, check to see if the 124: * relation is accessed FOR UPDATE/SHARE or not. We can't 125: * just grab AccessShareLock because then the executor would 126: * be trying to upgrade the lock, leading to possible 127: * deadlocks. 1.153 tgl 128: */ 129: if (rt_index == parsetree->resultRelation) 130: lockmode = RowExclusiveLock; 1.163 tgl 131: else if (get_rowmark(parsetree, rt_index)) 1.153 tgl 132: lockmode = RowShareLock; 133: else 134: lockmode = AccessShareLock; 135: 136: rel = heap_open(rte->relid, lockmode); 137: heap_close(rel, NoLock); 138: break; 139: 140: case RTE_JOIN: 1.158 momjian 141: 1.153 tgl 142: /* 1.158 momjian 143: * Scan the join's alias var list to see if any columns have 144: * been dropped, and if so replace those Vars with NULL 145: * Consts. 1.154 tgl 146: * 1.158 momjian 147: * Since a join has only two inputs, we can expect to see 148: * multiple references to the same input RTE; optimize away 149: * multiple fetches. 1.153 tgl 150: */ 151: newaliasvars = NIL; 1.154 tgl 152: curinputvarno = 0; 153: curinputrte = NULL; 1.153 tgl 154: foreach(ll, rte->joinaliasvars) 155: { 156: Var *aliasvar = (Var *) lfirst(ll); 157: 158: /* 159: * If the list item isn't a simple Var, then it must 160: * represent a merged column, ie a USING column, and so it 161: * couldn't possibly be dropped, since it's referenced in 1.158 momjian 162: * the join clause. (Conceivably it could also be a NULL 163: * constant already? But that's OK too.) 1.153 tgl 164: */ 165: if (IsA(aliasvar, Var)) 166: { 167: /* 168: * The elements of an alias list have to refer to 1.158 momjian 169: * earlier RTEs of the same rtable, because that's the 170: * order the planner builds things in. So we already 171: * processed the referenced RTE, and so it's safe to 172: * use get_rte_attribute_is_dropped on it. (This might 173: * not hold after rewriting or planning, but it's OK 174: * to assume here.) 1.153 tgl 175: */ 176: Assert(aliasvar->varlevelsup == 0); 1.154 tgl 177: if (aliasvar->varno != curinputvarno) 178: { 179: curinputvarno = aliasvar->varno; 180: if (curinputvarno >= rt_index) 181: elog(ERROR, "unexpected varno %d in JOIN RTE %d", 182: curinputvarno, rt_index); 183: curinputrte = rt_fetch(curinputvarno, 184: parsetree->rtable); 185: } 186: if (get_rte_attribute_is_dropped(curinputrte, 187: aliasvar->varattno)) 1.153 tgl 188: { 189: /* 190: * can't use vartype here, since that might be a 191: * now-dropped type OID, but it doesn't really 192: * matter what type the Const claims to be. 193: */ 194: aliasvar = (Var *) makeNullConst(INT4OID); 195: } 196: } 197: newaliasvars = lappend(newaliasvars, aliasvar); 198: } 199: rte->joinaliasvars = newaliasvars; 200: break; 201: 202: case RTE_SUBQUERY: 1.158 momjian 203: 1.153 tgl 204: /* 205: * The subquery RTE itself is all right, but we have to 206: * recurse to process the represented subquery. 207: */ 208: AcquireRewriteLocks(rte->subquery); 209: break; 210: 211: default: 212: /* ignore other types of RTEs */ 213: break; 214: } 215: } 216: 217: /* 1.158 momjian 218: * Recurse into sublink subqueries, too. But we already did the ones in 219: * the rtable. 1.153 tgl 220: */ 221: if (parsetree->hasSubLinks) 222: query_tree_walker(parsetree, acquireLocksOnSubLinks, NULL, 223: QTW_IGNORE_RT_SUBQUERIES); 224: } 225: 226: /* 227: * Walker to find sublink subqueries for AcquireRewriteLocks 228: */ 229: static bool 230: acquireLocksOnSubLinks(Node *node, void *context) 231: { 232: if (node == NULL) 233: return false; 234: if (IsA(node, SubLink)) 235: { 236: SubLink *sub = (SubLink *) node; 237: 238: /* Do what we came for */ 239: AcquireRewriteLocks((Query *) sub->subselect); 240: /* Fall through to process lefthand args of SubLink */ 241: } 242: 243: /* 244: * Do NOT recurse into Query nodes, because AcquireRewriteLocks already 245: * processed subselects of subselects for us. 246: */ 247: return expression_tree_walker(node, acquireLocksOnSubLinks, context); 248: } 249: 250: 251: /* 1.95 tgl 252: * rewriteRuleAction - 253: * Rewrite the rule action with appropriate qualifiers (taken from 254: * the triggering query). 1.166 tgl 255: * 256: * Input arguments: 257: * parsetree - original query 258: * rule_action - one action (query) of a rule 259: * rule_qual - WHERE condition of rule, or NULL if unconditional 260: * rt_index - RT index of result relation in original query 261: * event - type of rule event 262: * Output arguments: 263: * *returning_flag - set TRUE if we rewrite RETURNING clause in rule_action 264: * (must be initialized to FALSE) 265: * Return value: 266: * rewritten form of rule_action 1.1 scrappy 267: */ 1.95 tgl 268: static Query * 269: rewriteRuleAction(Query *parsetree, 1.6 momjian 270: Query *rule_action, 271: Node *rule_qual, 1.4 momjian 272: int rt_index, 1.166 tgl 273: CmdType event, 274: bool *returning_flag) 1.4 momjian 275: { 1.95 tgl 276: int current_varno, 277: new_varno; 278: int rt_length; 1.84 tgl 279: Query *sub_action; 280: Query **sub_action_ptr; 1.4 momjian 281: 1.95 tgl 282: /* 1.158 momjian 283: * Make modifiable copies of rule action and qual (what we're passed are 284: * the stored versions in the relcache; don't touch 'em!). 1.95 tgl 285: */ 286: rule_action = (Query *) copyObject(rule_action); 287: rule_qual = (Node *) copyObject(rule_qual); 288: 1.153 tgl 289: /* 290: * Acquire necessary locks and fix any deleted JOIN RTE entries. 291: */ 292: AcquireRewriteLocks(rule_action); 293: (void) acquireLocksOnSubLinks(rule_qual, NULL); 294: 1.95 tgl 295: current_varno = rt_index; 1.138 neilc 296: rt_length = list_length(parsetree->rtable); 1.95 tgl 297: new_varno = PRS2_NEW_VARNO + rt_length; 1.84 tgl 298: 299: /* 1.158 momjian 300: * Adjust rule action and qual to offset its varnos, so that we can merge 301: * its rtable with the main parsetree's rtable. 1.84 tgl 302: * 1.159 momjian 303: * If the rule action is an INSERT...SELECT, the OLD/NEW rtable entries 304: * will be in the SELECT part, and we have to modify that rather than the 1.158 momjian 305: * top-level INSERT (kluge!). 1.84 tgl 306: */ 1.95 tgl 307: sub_action = getInsertSelectQuery(rule_action, &sub_action_ptr); 1.84 tgl 308: 309: OffsetVarNodes((Node *) sub_action, rt_length, 0); 1.95 tgl 310: OffsetVarNodes(rule_qual, rt_length, 0); 1.84 tgl 311: /* but references to *OLD* should point at original rt_index */ 312: ChangeVarNodes((Node *) sub_action, 313: PRS2_OLD_VARNO + rt_length, rt_index, 0); 1.95 tgl 314: ChangeVarNodes(rule_qual, 1.84 tgl 315: PRS2_OLD_VARNO + rt_length, rt_index, 0); 316: 317: /* 1.98 momjian 318: * Generate expanded rtable consisting of main parsetree's rtable plus 319: * rule action's rtable; this becomes the complete rtable for the rule 1.158 momjian 320: * action. Some of the entries may be unused after we finish rewriting, 321: * but we leave them all in place for two reasons: 1.132 tgl 322: * 1.159 momjian 323: * We'd have a much harder job to adjust the query's varnos if we 324: * selectively removed RT entries. 1.132 tgl 325: * 1.159 momjian 326: * If the rule is INSTEAD, then the original query won't be executed at 327: * all, and so its rtable must be preserved so that the executor will do 328: * the correct permissions checks on it. 1.132 tgl 329: * 330: * RT entries that are not referenced in the completed jointree will be 1.158 momjian 331: * ignored by the planner, so they do not affect query semantics. But any 332: * permissions checks specified in them will be applied during executor 333: * startup (see ExecCheckRTEPerms()). This allows us to check that the 334: * caller has, say, insert-permission on a view, when the view is not 335: * semantically referenced at all in the resulting query. 1.132 tgl 336: * 1.159 momjian 337: * When a rule is not INSTEAD, the permissions checks done on its copied 338: * RT entries will be redundant with those done during execution of the 1.158 momjian 339: * original query, but we don't bother to treat that case differently. 1.84 tgl 340: * 1.159 momjian 341: * NOTE: because planner will destructively alter rtable, we must ensure 342: * that rule action's rtable is separate and shares no substructure with 343: * the main rtable. Hence do a deep copy here. 1.94 tgl 344: */ 1.138 neilc 345: sub_action->rtable = list_concat((List *) copyObject(parsetree->rtable), 1.144 momjian 346: sub_action->rtable); 1.84 tgl 347: 348: /* 349: * Each rule action's jointree should be the main parsetree's jointree 1.158 momjian 350: * plus that rule's jointree, but usually *without* the original rtindex 351: * that we're replacing (if present, which it won't be for INSERT). Note 352: * that if the rule action refers to OLD, its jointree will add a 353: * reference to rt_index. If the rule action doesn't refer to OLD, but 354: * either the rule_qual or the user query quals do, then we need to keep 355: * the original rtindex in the jointree to provide data for the quals. We 356: * don't want the original rtindex to be joined twice, however, so avoid 357: * keeping it if the rule action mentions it. 1.94 tgl 358: * 1.159 momjian 359: * As above, the action's jointree must not share substructure with the 360: * main parsetree's. 1.84 tgl 361: */ 1.123 tgl 362: if (sub_action->commandType != CMD_UTILITY) 1.84 tgl 363: { 1.90 momjian 364: bool keeporig; 365: List *newjointree; 1.84 tgl 366: 1.123 tgl 367: Assert(sub_action->jointree != NULL); 1.90 momjian 368: keeporig = (!rangeTableEntry_used((Node *) sub_action->jointree, 369: rt_index, 0)) && 1.95 tgl 370: (rangeTableEntry_used(rule_qual, rt_index, 0) || 1.158 momjian 371: rangeTableEntry_used(parsetree->jointree->quals, rt_index, 0)); 1.89 tgl 372: newjointree = adjustJoinTreeList(parsetree, !keeporig, rt_index); 1.123 tgl 373: if (newjointree != NIL) 374: { 375: /* 1.158 momjian 376: * If sub_action is a setop, manipulating its jointree will do no 377: * good at all, because the jointree is dummy. (Perhaps someday 378: * we could push the joining and quals down to the member 379: * statements of the setop?) 1.123 tgl 380: */ 381: if (sub_action->setOperations != NULL) 1.124 tgl 382: ereport(ERROR, 383: (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), 384: errmsg("conditional UNION/INTERSECT/EXCEPT statements are not implemented"))); 1.123 tgl 385: 386: sub_action->jointree->fromlist = 1.138 neilc 387: list_concat(newjointree, sub_action->jointree->fromlist); 1.160 tgl 388: 389: /* 390: * There could have been some SubLinks in newjointree, in which 391: * case we'd better mark the sub_action correctly. 392: */ 393: if (parsetree->hasSubLinks && !sub_action->hasSubLinks) 394: sub_action->hasSubLinks = 395: checkExprHasSubLink((Node *) newjointree); 1.123 tgl 396: } 1.84 tgl 397: } 398: 399: /* 1.158 momjian 400: * Event Qualification forces copying of parsetree and splitting into two 401: * queries one w/rule_qual, one w/NOT rule_qual. Also add user query qual 402: * onto rule action 1.84 tgl 403: */ 1.95 tgl 404: AddQual(sub_action, rule_qual); 1.84 tgl 405: 406: AddQual(sub_action, parsetree->jointree->quals); 1.4 momjian 407: 1.84 tgl 408: /* 1.90 momjian 409: * Rewrite new.attribute w/ right hand side of target-list entry for 410: * appropriate field name in insert/update. 1.84 tgl 411: * 1.159 momjian 412: * KLUGE ALERT: since ResolveNew returns a mutated copy, we can't just 413: * apply it to sub_action; we have to remember to update the sublink 414: * inside rule_action, too. 1.84 tgl 415: */ 1.141 tgl 416: if ((event == CMD_INSERT || event == CMD_UPDATE) && 417: sub_action->commandType != CMD_UTILITY) 1.84 tgl 418: { 419: sub_action = (Query *) ResolveNew((Node *) sub_action, 1.95 tgl 420: new_varno, 1.84 tgl 421: 0, 1.154 tgl 422: rt_fetch(new_varno, 423: sub_action->rtable), 1.84 tgl 424: parsetree->targetList, 1.95 tgl 425: event, 426: current_varno); 1.84 tgl 427: if (sub_action_ptr) 428: *sub_action_ptr = sub_action; 429: else 1.95 tgl 430: rule_action = sub_action; 1.4 momjian 431: } 1.84 tgl 432: 1.166 tgl 433: /* 1.167 momjian 434: * If rule_action has a RETURNING clause, then either throw it away if the 435: * triggering query has no RETURNING clause, or rewrite it to emit what 436: * the triggering query's RETURNING clause asks for. Throw an error if 437: * more than one rule has a RETURNING clause. 1.166 tgl 438: */ 439: if (!parsetree->returningList) 440: rule_action->returningList = NIL; 441: else if (rule_action->returningList) 442: { 443: if (*returning_flag) 444: ereport(ERROR, 445: (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), 1.167 momjian 446: errmsg("cannot have RETURNING lists in multiple rules"))); 1.166 tgl 447: *returning_flag = true; 448: rule_action->returningList = (List *) 449: ResolveNew((Node *) parsetree->returningList, 450: parsetree->resultRelation, 451: 0, 452: rt_fetch(parsetree->resultRelation, 453: parsetree->rtable), 454: rule_action->returningList, 455: CMD_SELECT, 456: 0); 457: } 458: 1.95 tgl 459: return rule_action; 1.4 momjian 460: } 461: 1.22 momjian 462: /* 1.89 tgl 463: * Copy the query's jointree list, and optionally attempt to remove any 464: * occurrence of the given rt_index as a top-level join item (we do not look 465: * for it within join items; this is OK because we are only expecting to find 466: * it as an UPDATE or DELETE target relation, which will be at the top level 1.94 tgl 467: * of the join). Returns modified jointree list --- this is a separate copy 468: * sharing no nodes with the original. 1.22 momjian 469: */ 1.80 tgl 470: static List * 1.89 tgl 471: adjustJoinTreeList(Query *parsetree, bool removert, int rt_index) 1.71 momjian 472: { 1.94 tgl 473: List *newjointree = copyObject(parsetree->jointree->fromlist); 1.136 neilc 474: ListCell *l; 1.58 tgl 475: 1.89 tgl 476: if (removert) 1.58 tgl 477: { 1.136 neilc 478: foreach(l, newjointree) 1.89 tgl 479: { 1.136 neilc 480: RangeTblRef *rtr = lfirst(l); 1.22 momjian 481: 1.115 tgl 482: if (IsA(rtr, RangeTblRef) && 483: rtr->rtindex == rt_index) 1.89 tgl 484: { 1.138 neilc 485: newjointree = list_delete_ptr(newjointree, rtr); 1.144 momjian 486: 487: /* 1.158 momjian 488: * foreach is safe because we exit loop after list_delete... 1.144 momjian 489: */ 1.89 tgl 490: break; 491: } 1.80 tgl 492: } 1.58 tgl 493: } 1.80 tgl 494: return newjointree; 1.22 momjian 495: } 1.20 momjian 496: 1.4 momjian 497: 1.22 momjian 498: /* 1.101 tgl 499: * rewriteTargetList - rewrite INSERT/UPDATE targetlist into standard form 500: * 501: * This has the following responsibilities: 502: * 503: * 1. For an INSERT, add tlist entries to compute default values for any 504: * attributes that have defaults and are not assigned to in the given tlist. 505: * (We do not insert anything for default-less attributes, however. The 506: * planner will later insert NULLs for them, but there's no reason to slow 1.122 tgl 507: * down rewriter processing with extra tlist nodes.) Also, for both INSERT 508: * and UPDATE, replace explicit DEFAULT specifications with column default 509: * expressions. 1.101 tgl 510: * 511: * 2. Merge multiple entries for the same target attribute, or declare error 1.139 tgl 512: * if we can't. Multiple entries are only allowed for INSERT/UPDATE of 513: * portions of an array or record field, for example 514: * UPDATE table SET foo[2] = 42, foo[4] = 43; 1.101 tgl 515: * We can merge such operations into a single assignment op. Essentially, 516: * the expression we want to produce in this case is like 517: * foo = array_set(array_set(foo, 2, 42), 4, 43) 518: * 519: * 3. Sort the tlist into standard order: non-junk fields in order by resno, 520: * then junk fields (these in no particular order). 521: * 522: * We must do items 1 and 2 before firing rewrite rules, else rewritten 1.108 momjian 523: * references to NEW.foo will produce wrong or incomplete results. Item 3 1.101 tgl 524: * is not needed for rewriting, but will be needed by the planner, and we 525: * can do it essentially for free while handling items 1 and 2. 1.165 joe 526: * 527: * If attrno_list isn't NULL, we return an additional output besides the 528: * rewritten targetlist: an integer list of the assigned-to attnums, in 529: * order of the original tlist's non-junk entries. This is needed for 530: * processing VALUES RTEs. 1.101 tgl 531: */ 532: static void 1.165 joe 533: rewriteTargetList(Query *parsetree, Relation target_relation, 534: List **attrno_list) 1.101 tgl 535: { 536: CmdType commandType = parsetree->commandType; 1.149 tgl 537: TargetEntry **new_tles; 1.101 tgl 538: List *new_tlist = NIL; 1.149 tgl 539: List *junk_tlist = NIL; 540: Form_pg_attribute att_tup; 1.101 tgl 541: int attrno, 1.149 tgl 542: next_junk_attrno, 1.101 tgl 543: numattrs; 1.136 neilc 544: ListCell *temp; 1.101 tgl 545: 1.165 joe 546: if (attrno_list) /* initialize optional result list */ 547: *attrno_list = NIL; 548: 1.101 tgl 549: /* 1.158 momjian 550: * We process the normal (non-junk) attributes by scanning the input tlist 551: * once and transferring TLEs into an array, then scanning the array to 552: * build an output tlist. This avoids O(N^2) behavior for large numbers 553: * of attributes. 1.149 tgl 554: * 1.158 momjian 555: * Junk attributes are tossed into a separate list during the same tlist 556: * scan, then appended to the reconstructed tlist. 1.101 tgl 557: */ 558: numattrs = RelationGetNumberOfAttributes(target_relation); 1.149 tgl 559: new_tles = (TargetEntry **) palloc0(numattrs * sizeof(TargetEntry *)); 560: next_junk_attrno = numattrs + 1; 1.101 tgl 561: 1.149 tgl 562: foreach(temp, parsetree->targetList) 1.101 tgl 563: { 1.149 tgl 564: TargetEntry *old_tle = (TargetEntry *) lfirst(temp); 565: 1.150 tgl 566: if (!old_tle->resjunk) 1.149 tgl 567: { 568: /* Normal attr: stash it into new_tles[] */ 1.150 tgl 569: attrno = old_tle->resno; 1.149 tgl 570: if (attrno < 1 || attrno > numattrs) 571: elog(ERROR, "bogus resno %d in targetlist", attrno); 572: att_tup = target_relation->rd_att->attrs[attrno - 1]; 1.105 tgl 573: 1.165 joe 574: /* put attrno into attrno_list even if it's dropped */ 575: if (attrno_list) 576: *attrno_list = lappend_int(*attrno_list, attrno); 577: 1.149 tgl 578: /* We can (and must) ignore deleted attributes */ 579: if (att_tup->attisdropped) 580: continue; 1.101 tgl 581: 1.149 tgl 582: /* Merge with any prior assignment to same attribute */ 583: new_tles[attrno - 1] = 584: process_matched_tle(old_tle, 585: new_tles[attrno - 1], 586: NameStr(att_tup->attname)); 587: } 588: else 1.101 tgl 589: { 1.149 tgl 590: /* 1.158 momjian 591: * Copy all resjunk tlist entries to junk_tlist, and assign them 592: * resnos above the last real resno. 1.149 tgl 593: * 1.159 momjian 594: * Typical junk entries include ORDER BY or GROUP BY expressions 595: * (are these actually possible in an INSERT or UPDATE?), system 1.149 tgl 596: * attribute references, etc. 597: */ 1.101 tgl 598: 1.149 tgl 599: /* Get the resno right, but don't copy unnecessarily */ 1.150 tgl 600: if (old_tle->resno != next_junk_attrno) 1.101 tgl 601: { 1.150 tgl 602: old_tle = flatCopyTargetEntry(old_tle); 603: old_tle->resno = next_junk_attrno; 1.101 tgl 604: } 1.149 tgl 605: junk_tlist = lappend(junk_tlist, old_tle); 606: next_junk_attrno++; 1.101 tgl 607: } 1.149 tgl 608: } 609: 610: for (attrno = 1; attrno <= numattrs; attrno++) 611: { 612: TargetEntry *new_tle = new_tles[attrno - 1]; 613: 614: att_tup = target_relation->rd_att->attrs[attrno - 1]; 615: 616: /* We can (and must) ignore deleted attributes */ 617: if (att_tup->attisdropped) 618: continue; 1.101 tgl 619: 1.122 tgl 620: /* 1.158 momjian 621: * Handle the two cases where we need to insert a default expression: 622: * it's an INSERT and there's no tlist entry for the column, or the 623: * tlist entry is a DEFAULT placeholder node. 1.122 tgl 624: */ 625: if ((new_tle == NULL && commandType == CMD_INSERT) || 1.149 tgl 626: (new_tle && new_tle->expr && IsA(new_tle->expr, SetToDefault))) 1.101 tgl 627: { 628: Node *new_expr; 629: 630: new_expr = build_column_default(target_relation, attrno); 1.122 tgl 631: 632: /* 1.158 momjian 633: * If there is no default (ie, default is effectively NULL), we 634: * can omit the tlist entry in the INSERT case, since the planner 635: * can insert a NULL for itself, and there's no point in spending 636: * any more rewriter cycles on the entry. But in the UPDATE case 637: * we've got to explicitly set the column to NULL. 1.122 tgl 638: */ 639: if (!new_expr) 640: { 641: if (commandType == CMD_INSERT) 642: new_tle = NULL; 643: else 644: { 645: new_expr = (Node *) makeConst(att_tup->atttypid, 646: att_tup->attlen, 647: (Datum) 0, 648: true, /* isnull */ 649: att_tup->attbyval); 650: /* this is to catch a NOT NULL domain constraint */ 651: new_expr = coerce_to_domain(new_expr, 1.162 tgl 652: InvalidOid, -1, 1.122 tgl 653: att_tup->atttypid, 1.140 tgl 654: COERCE_IMPLICIT_CAST, 1.145 tgl 655: false, 1.140 tgl 656: false); 1.122 tgl 657: } 658: } 1.101 tgl 659: 660: if (new_expr) 1.150 tgl 661: new_tle = makeTargetEntry((Expr *) new_expr, 662: attrno, 663: pstrdup(NameStr(att_tup->attname)), 664: false); 1.101 tgl 665: } 666: 667: if (new_tle) 668: new_tlist = lappend(new_tlist, new_tle); 669: } 670: 1.149 tgl 671: pfree(new_tles); 1.101 tgl 672: 1.149 tgl 673: parsetree->targetList = list_concat(new_tlist, junk_tlist); 1.101 tgl 674: } 675: 676: 677: /* 678: * Convert a matched TLE from the original tlist into a correct new TLE. 679: * 680: * This routine detects and handles multiple assignments to the same target 1.129 tgl 681: * attribute. (The attribute name is needed only for error messages.) 1.101 tgl 682: */ 683: static TargetEntry * 684: process_matched_tle(TargetEntry *src_tle, 1.129 tgl 685: TargetEntry *prior_tle, 686: const char *attrName) 1.101 tgl 687: { 1.150 tgl 688: TargetEntry *result; 1.139 tgl 689: Node *src_expr; 690: Node *prior_expr; 691: Node *src_input; 692: Node *prior_input; 1.101 tgl 693: Node *priorbottom; 1.139 tgl 694: Node *newexpr; 1.101 tgl 695: 696: if (prior_tle == NULL) 697: { 698: /* 1.158 momjian 699: * Normal case where this is the first assignment to the attribute. 1.101 tgl 700: */ 701: return src_tle; 702: } 703: 1.139 tgl 704: /*---------- 1.101 tgl 705: * Multiple assignments to same attribute. Allow only if all are 1.139 tgl 706: * FieldStore or ArrayRef assignment operations. This is a bit 707: * tricky because what we may actually be looking at is a nest of 708: * such nodes; consider 709: * UPDATE tab SET col.fld1.subfld1 = x, col.fld2.subfld2 = y 710: * The two expressions produced by the parser will look like 711: * FieldStore(col, fld1, FieldStore(placeholder, subfld1, x)) 712: * FieldStore(col, fld2, FieldStore(placeholder, subfld2, x)) 713: * However, we can ignore the substructure and just consider the top 714: * FieldStore or ArrayRef from each assignment, because it works to 715: * combine these as 716: * FieldStore(FieldStore(col, fld1, 717: * FieldStore(placeholder, subfld1, x)), 718: * fld2, FieldStore(placeholder, subfld2, x)) 719: * Note the leftmost expression goes on the inside so that the 720: * assignments appear to occur left-to-right. 721: * 722: * For FieldStore, instead of nesting we can generate a single 1.144 momjian 723: * FieldStore with multiple target fields. We must nest when 1.139 tgl 724: * ArrayRefs are involved though. 725: *---------- 726: */ 727: src_expr = (Node *) src_tle->expr; 728: prior_expr = (Node *) prior_tle->expr; 729: src_input = get_assignment_input(src_expr); 730: prior_input = get_assignment_input(prior_expr); 731: if (src_input == NULL || 732: prior_input == NULL || 733: exprType(src_expr) != exprType(prior_expr)) 1.124 tgl 734: ereport(ERROR, 735: (errcode(ERRCODE_SYNTAX_ERROR), 1.130 petere 736: errmsg("multiple assignments to same column \"%s\"", 1.129 tgl 737: attrName))); 1.101 tgl 738: 739: /* 1.158 momjian 740: * Prior TLE could be a nest of assignments if we do this more than once. 1.101 tgl 741: */ 1.139 tgl 742: priorbottom = prior_input; 743: for (;;) 744: { 1.144 momjian 745: Node *newbottom = get_assignment_input(priorbottom); 1.139 tgl 746: 747: if (newbottom == NULL) 748: break; /* found the original Var reference */ 749: priorbottom = newbottom; 750: } 751: if (!equal(priorbottom, src_input)) 1.124 tgl 752: ereport(ERROR, 753: (errcode(ERRCODE_SYNTAX_ERROR), 1.130 petere 754: errmsg("multiple assignments to same column \"%s\"", 1.129 tgl 755: attrName))); 1.101 tgl 756: 757: /* 758: * Looks OK to nest 'em. 759: */ 1.139 tgl 760: if (IsA(src_expr, FieldStore)) 761: { 1.144 momjian 762: FieldStore *fstore = makeNode(FieldStore); 1.139 tgl 763: 764: if (IsA(prior_expr, FieldStore)) 765: { 766: /* combine the two */ 767: memcpy(fstore, prior_expr, sizeof(FieldStore)); 768: fstore->newvals = 769: list_concat(list_copy(((FieldStore *) prior_expr)->newvals), 1.158 momjian 770: list_copy(((FieldStore *) src_expr)->newvals)); 1.139 tgl 771: fstore->fieldnums = 772: list_concat(list_copy(((FieldStore *) prior_expr)->fieldnums), 1.158 momjian 773: list_copy(((FieldStore *) src_expr)->fieldnums)); 1.139 tgl 774: } 775: else 776: { 777: /* general case, just nest 'em */ 778: memcpy(fstore, src_expr, sizeof(FieldStore)); 779: fstore->arg = (Expr *) prior_expr; 780: } 781: newexpr = (Node *) fstore; 782: } 783: else if (IsA(src_expr, ArrayRef)) 784: { 785: ArrayRef *aref = makeNode(ArrayRef); 786: 787: memcpy(aref, src_expr, sizeof(ArrayRef)); 788: aref->refexpr = (Expr *) prior_expr; 789: newexpr = (Node *) aref; 790: } 791: else 792: { 793: elog(ERROR, "can't happen"); 794: newexpr = NULL; 795: } 1.101 tgl 796: 1.150 tgl 797: result = flatCopyTargetEntry(src_tle); 798: result->expr = (Expr *) newexpr; 799: return result; 1.101 tgl 800: } 801: 1.139 tgl 802: /* 803: * If node is an assignment node, return its input; else return NULL 804: */ 805: static Node * 806: get_assignment_input(Node *node) 807: { 808: if (node == NULL) 809: return NULL; 810: if (IsA(node, FieldStore)) 811: { 812: FieldStore *fstore = (FieldStore *) node; 813: 814: return (Node *) fstore->arg; 815: } 816: else if (IsA(node, ArrayRef)) 817: { 818: ArrayRef *aref = (ArrayRef *) node; 819: 820: if (aref->refassgnexpr == NULL) 821: return NULL; 822: return (Node *) aref->refexpr; 823: } 824: return NULL; 825: } 1.101 tgl 826: 827: /* 828: * Make an expression tree for the default value for a column. 829: * 830: * If there is no default, return a NULL instead. 831: */ 1.104 momjian 832: Node * 1.101 tgl 833: build_column_default(Relation rel, int attrno) 834: { 835: TupleDesc rd_att = rel->rd_att; 836: Form_pg_attribute att_tup = rd_att->attrs[attrno - 1]; 837: Oid atttype = att_tup->atttypid; 838: int32 atttypmod = att_tup->atttypmod; 839: Node *expr = NULL; 840: Oid exprtype; 841: 842: /* 843: * Scan to see if relation has a default for this column. 844: */ 845: if (rd_att->constr && rd_att->constr->num_defval > 0) 846: { 847: AttrDefault *defval = rd_att->constr->defval; 848: int ndef = rd_att->constr->num_defval; 849: 850: while (--ndef >= 0) 851: { 852: if (attrno == defval[ndef].adnum) 853: { 854: /* 855: * Found it, convert string representation to node tree. 856: */ 857: expr = stringToNode(defval[ndef].adbin); 858: break; 859: } 860: } 861: } 862: 863: if (expr == NULL) 864: { 865: /* 1.158 momjian 866: * No per-column default, so look for a default for the type itself. 1.101 tgl 867: */ 1.134 tgl 868: expr = get_typdefault(atttype); 1.101 tgl 869: } 870: 871: if (expr == NULL) 872: return NULL; /* No default anywhere */ 873: 874: /* 1.125 tgl 875: * Make sure the value is coerced to the target column type; this will 876: * generally be true already, but there seem to be some corner cases 1.158 momjian 877: * involving domain defaults where it might not be true. This should match 878: * the parser's processing of non-defaulted expressions --- see 1.165 joe 879: * transformAssignedExpr(). 1.101 tgl 880: */ 881: exprtype = exprType(expr); 882: 1.126 momjian 883: expr = coerce_to_target_type(NULL, /* no UNKNOWN params here */ 1.119 tgl 884: expr, exprtype, 1.110 tgl 885: atttype, atttypmod, 886: COERCION_ASSIGNMENT, 887: COERCE_IMPLICIT_CAST); 888: if (expr == NULL) 1.124 tgl 889: ereport(ERROR, 890: (errcode(ERRCODE_DATATYPE_MISMATCH), 891: errmsg("column \"%s\" is of type %s" 892: " but default expression is of type %s", 893: NameStr(att_tup->attname), 894: format_type_be(atttype), 895: format_type_be(exprtype)), 1.158 momjian 896: errhint("You will need to rewrite or cast the expression."))); 1.101 tgl 897: 898: return expr; 899: } 900: 901: 1.165 joe 902: /* Does VALUES RTE contain any SetToDefault items? */ 903: static bool 904: searchForDefault(RangeTblEntry *rte) 905: { 906: ListCell *lc; 907: 908: foreach(lc, rte->values_lists) 909: { 1.167 momjian 910: List *sublist = (List *) lfirst(lc); 911: ListCell *lc2; 1.165 joe 912: 913: foreach(lc2, sublist) 914: { 1.167 momjian 915: Node *col = (Node *) lfirst(lc2); 1.165 joe 916: 917: if (IsA(col, SetToDefault)) 918: return true; 919: } 920: } 921: return false; 922: } 923: 924: /* 925: * When processing INSERT ... VALUES with a VALUES RTE (ie, multiple VALUES 926: * lists), we have to replace any DEFAULT items in the VALUES lists with 927: * the appropriate default expressions. The other aspects of rewriteTargetList 928: * need be applied only to the query's targetlist proper. 929: * 930: * Note that we currently can't support subscripted or field assignment 931: * in the multi-VALUES case. The targetlist will contain simple Vars 932: * referencing the VALUES RTE, and therefore process_matched_tle() will 933: * reject any such attempt with "multiple assignments to same column". 934: */ 935: static void 936: rewriteValuesRTE(RangeTblEntry *rte, Relation target_relation, List *attrnos) 937: { 938: List *newValues; 939: ListCell *lc; 940: 941: /* 942: * Rebuilding all the lists is a pretty expensive proposition in a big 943: * VALUES list, and it's a waste of time if there aren't any DEFAULT 944: * placeholders. So first scan to see if there are any. 945: */ 946: if (!searchForDefault(rte)) 947: return; /* nothing to do */ 948: 949: /* Check list lengths (we can assume all the VALUES sublists are alike) */ 950: Assert(list_length(attrnos) == list_length(linitial(rte->values_lists))); 951: 952: newValues = NIL; 953: foreach(lc, rte->values_lists) 954: { 1.167 momjian 955: List *sublist = (List *) lfirst(lc); 956: List *newList = NIL; 957: ListCell *lc2; 958: ListCell *lc3; 1.165 joe 959: 960: forboth(lc2, sublist, lc3, attrnos) 961: { 1.167 momjian 962: Node *col = (Node *) lfirst(lc2); 963: int attrno = lfirst_int(lc3); 1.165 joe 964: 965: if (IsA(col, SetToDefault)) 966: { 967: Form_pg_attribute att_tup; 968: Node *new_expr; 969: 970: att_tup = target_relation->rd_att->attrs[attrno - 1]; 971: 972: if (!att_tup->attisdropped) 973: new_expr = build_column_default(target_relation, attrno); 974: else 1.167 momjian 975: new_expr = NULL; /* force a NULL if dropped */ 1.165 joe 976: 977: /* 978: * If there is no default (ie, default is effectively NULL), 979: * we've got to explicitly set the column to NULL. 980: */ 981: if (!new_expr) 982: { 983: new_expr = (Node *) makeConst(att_tup->atttypid, 984: att_tup->attlen, 985: (Datum) 0, 986: true, /* isnull */ 987: att_tup->attbyval); 988: /* this is to catch a NOT NULL domain constraint */ 989: new_expr = coerce_to_domain(new_expr, 990: InvalidOid, -1, 991: att_tup->atttypid, 992: COERCE_IMPLICIT_CAST, 993: false, 994: false); 995: } 996: newList = lappend(newList, new_expr); 997: } 998: else 999: newList = lappend(newList, col); 1000: } 1001: newValues = lappend(newValues, newList); 1002: } 1003: rte->values_lists = newValues; 1004: } 1005: 1006: 1.101 tgl 1007: /* 1.81 tgl 1008: * matchLocks - 1009: * match the list of locks and returns the matching rules 1.22 momjian 1010: */ 1.81 tgl 1011: static List * 1012: matchLocks(CmdType event, 1013: RuleLock *rulelocks, 1014: int varno, 1015: Query *parsetree) 1.71 momjian 1016: { 1.112 tgl 1017: List *matching_locks = NIL; 1.81 tgl 1018: int nlocks; 1019: int i; 1.58 tgl 1020: 1.118 tgl 1021: if (rulelocks == NULL) 1022: return NIL; 1.22 momjian 1023: 1.81 tgl 1024: if (parsetree->commandType != CMD_SELECT) 1.58 tgl 1025: { 1.81 tgl 1026: if (parsetree->resultRelation != varno) 1027: return NIL; 1.58 tgl 1028: } 1.22 momjian 1029: 1.81 tgl 1030: nlocks = rulelocks->numLocks; 1.22 momjian 1031: 1.81 tgl 1032: for (i = 0; i < nlocks; i++) 1.45 momjian 1033: { 1.81 tgl 1034: RewriteRule *oneLock = rulelocks->rules[i]; 1.22 momjian 1035: 1.81 tgl 1036: if (oneLock->event == event) 1.63 tgl 1037: { 1.81 tgl 1038: if (parsetree->commandType != CMD_SELECT || 1039: (oneLock->attrno == -1 ? 1040: rangeTableEntry_used((Node *) parsetree, varno, 0) : 1041: attribute_used((Node *) parsetree, 1042: varno, oneLock->attrno, 0))) 1.112 tgl 1043: matching_locks = lappend(matching_locks, oneLock); 1.63 tgl 1044: } 1.22 momjian 1045: } 1.45 momjian 1046: 1.112 tgl 1047: return matching_locks; 1.58 tgl 1048: } 1.22 momjian 1049: 1050: 1.153 tgl 1051: /* 1052: * ApplyRetrieveRule - expand an ON SELECT rule 1053: */ 1.81 tgl 1054: static Query * 1055: ApplyRetrieveRule(Query *parsetree, 1056: RewriteRule *rule, 1057: int rt_index, 1058: bool relation_level, 1059: Relation relation, 1.118 tgl 1060: List *activeRIRs) 1.58 tgl 1061: { 1.81 tgl 1062: Query *rule_action; 1063: RangeTblEntry *rte, 1064: *subrte; 1.163 tgl 1065: RowMarkClause *rc; 1.22 momjian 1066: 1.138 neilc 1067: if (list_length(rule->actions) != 1) 1.124 tgl 1068: elog(ERROR, "expected just one rule action"); 1.81 tgl 1069: if (rule->qual != NULL) 1.124 tgl 1070: elog(ERROR, "cannot handle qualified ON SELECT rule"); 1.90 momjian 1071: if (!relation_level) 1.124 tgl 1072: elog(ERROR, "cannot handle per-attribute ON SELECT rule"); 1.71 momjian 1073: 1.63 tgl 1074: /* 1.158 momjian 1075: * Make a modifiable copy of the view query, and acquire needed locks on 1076: * the relations it mentions. 1.58 tgl 1077: */ 1.136 neilc 1078: rule_action = copyObject(linitial(rule->actions)); 1.22 momjian 1079: 1.153 tgl 1080: AcquireRewriteLocks(rule_action); 1081: 1082: /* 1083: * Recursively expand any view references inside the view. 1084: */ 1.118 tgl 1085: rule_action = fireRIRrules(rule_action, activeRIRs); 1.22 momjian 1086: 1.81 tgl 1087: /* 1.158 momjian 1088: * VIEWs are really easy --- just plug the view query in as a subselect, 1089: * replacing the relation's original RTE. 1.81 tgl 1090: */ 1091: rte = rt_fetch(rt_index, parsetree->rtable); 1.58 tgl 1092: 1.99 tgl 1093: rte->rtekind = RTE_SUBQUERY; 1.81 tgl 1094: rte->relid = InvalidOid; 1095: rte->subquery = rule_action; 1096: rte->inh = false; /* must not be set for a subquery */ 1.71 momjian 1097: 1.58 tgl 1098: /* 1.158 momjian 1099: * We move the view's permission check data down to its rangetable. The 1100: * checks will actually be done against the *OLD* entry therein. 1.58 tgl 1101: */ 1.81 tgl 1102: subrte = rt_fetch(PRS2_OLD_VARNO, rule_action->rtable); 1103: Assert(subrte->relid == relation->rd_id); 1.133 tgl 1104: subrte->requiredPerms = rte->requiredPerms; 1.93 tgl 1105: subrte->checkAsUser = rte->checkAsUser; 1.27 thomas 1106: 1.133 tgl 1107: rte->requiredPerms = 0; /* no permission check on subquery itself */ 1.155 tgl 1108: rte->checkAsUser = InvalidOid; 1.60 tgl 1109: 1.71 momjian 1110: /* 1.151 tgl 1111: * FOR UPDATE/SHARE of view? 1.60 tgl 1112: */ 1.163 tgl 1113: if ((rc = get_rowmark(parsetree, rt_index)) != NULL) 1.22 momjian 1114: { 1.45 momjian 1115: /* 1.158 momjian 1116: * Remove the view from the list of rels that will actually be marked 1.163 tgl 1117: * FOR UPDATE/SHARE by the executor. It will still be access-checked 1.158 momjian 1118: * for write access, though. 1.29 vadim 1119: */ 1.163 tgl 1120: parsetree->rowMarks = list_delete_ptr(parsetree->rowMarks, rc); 1.58 tgl 1121: 1.81 tgl 1122: /* 1.151 tgl 1123: * Set up the view's referenced tables as if FOR UPDATE/SHARE. 1.81 tgl 1124: */ 1.163 tgl 1125: markQueryForLocking(rule_action, rc->forUpdate, 1126: rc->noWait, true); 1.86 tgl 1127: } 1128: 1129: return parsetree; 1130: } 1131: 1132: /* 1.151 tgl 1133: * Recursively mark all relations used by a view as FOR UPDATE/SHARE. 1.86 tgl 1134: * 1135: * This may generate an invalid query, eg if some sub-query uses an 1136: * aggregate. We leave it to the planner to detect that. 1137: * 1.151 tgl 1138: * NB: this must agree with the parser's transformLocking() routine. 1.86 tgl 1139: */ 1140: static void 1.157 tgl 1141: markQueryForLocking(Query *qry, bool forUpdate, bool noWait, bool skipOldNew) 1.86 tgl 1142: { 1143: Index rti = 0; 1.136 neilc 1144: ListCell *l; 1.86 tgl 1145: 1146: foreach(l, qry->rtable) 1147: { 1148: RangeTblEntry *rte = (RangeTblEntry *) lfirst(l); 1149: 1150: rti++; 1151: 1152: /* Ignore OLD and NEW entries if we are at top level of view */ 1153: if (skipOldNew && 1154: (rti == PRS2_OLD_VARNO || rti == PRS2_NEW_VARNO)) 1155: continue; 1156: 1.99 tgl 1157: if (rte->rtekind == RTE_RELATION) 1.86 tgl 1158: { 1.163 tgl 1159: applyLockingClause(qry, rti, forUpdate, noWait); 1.133 tgl 1160: rte->requiredPerms |= ACL_SELECT_FOR_UPDATE; 1.29 vadim 1161: } 1.99 tgl 1162: else if (rte->rtekind == RTE_SUBQUERY) 1163: { 1.151 tgl 1164: /* FOR UPDATE/SHARE of subquery is propagated to subquery's rels */ 1.157 tgl 1165: markQueryForLocking(rte->subquery, forUpdate, noWait, false); 1.99 tgl 1166: } 1.29 vadim 1167: } 1.22 momjian 1168: } 1169: 1170: 1.58 tgl 1171: /* 1.81 tgl 1172: * fireRIRonSubLink - 1173: * Apply fireRIRrules() to each SubLink (subselect in expression) found 1174: * in the given tree. 1.58 tgl 1175: * 1176: * NOTE: although this has the form of a walker, we cheat and modify the 1.71 momjian 1177: * SubLink nodes in-place. It is caller's responsibility to ensure that 1.58 tgl 1178: * no unwanted side-effects occur! 1.80 tgl 1179: * 1180: * This is unlike most of the other routines that recurse into subselects, 1181: * because we must take control at the SubLink node in order to replace 1182: * the SubLink's subselect link with the possibly-rewritten subquery. 1.58 tgl 1183: */ 1184: static bool 1.118 tgl 1185: fireRIRonSubLink(Node *node, List *activeRIRs) 1.22 momjian 1186: { 1187: if (node == NULL) 1.58 tgl 1188: return false; 1189: if (IsA(node, SubLink)) 1190: { 1191: SubLink *sub = (SubLink *) node; 1.22 momjian 1192: 1.58 tgl 1193: /* Do what we came for */ 1.118 tgl 1194: sub->subselect = (Node *) fireRIRrules((Query *) sub->subselect, 1195: activeRIRs); 1.80 tgl 1196: /* Fall through to process lefthand args of SubLink */ 1.22 momjian 1197: } 1.90 momjian 1198: 1.80 tgl 1199: /* 1.158 momjian 1200: * Do NOT recurse into Query nodes, because fireRIRrules already processed 1201: * subselects of subselects for us. 1.80 tgl 1202: */ 1.81 tgl 1203: return expression_tree_walker(node, fireRIRonSubLink, 1.118 tgl 1204: (void *) activeRIRs); 1.22 momjian 1205: } 1206: 1207: 1208: /* 1209: * fireRIRrules - 1210: * Apply all RIR rules on each rangetable entry in a query 1211: */ 1212: static Query * 1.118 tgl 1213: fireRIRrules(Query *parsetree, List *activeRIRs) 1.22 momjian 1214: { 1.45 momjian 1215: int rt_index; 1.22 momjian 1216: 1.71 momjian 1217: /* 1.158 momjian 1218: * don't try to convert this into a foreach loop, because rtable list can 1219: * get changed each time through... 1.60 tgl 1220: */ 1.22 momjian 1221: rt_index = 0; 1.138 neilc 1222: while (rt_index < list_length(parsetree->rtable)) 1.45 momjian 1223: { 1.83 tgl 1224: RangeTblEntry *rte; 1225: Relation rel; 1226: List *locks; 1227: RuleLock *rules; 1228: RewriteRule *rule; 1229: int i; 1230: 1.22 momjian 1231: ++rt_index; 1232: 1.62 tgl 1233: rte = rt_fetch(rt_index, parsetree->rtable); 1.44 wieck 1234: 1.60 tgl 1235: /* 1.158 momjian 1236: * A subquery RTE can't have associated rules, so there's nothing to 1237: * do to this level of the query, but we must recurse into the 1.81 tgl 1238: * subquery to expand any rule references in it. 1239: */ 1.99 tgl 1240: if (rte->rtekind == RTE_SUBQUERY) 1.81 tgl 1241: { 1.118 tgl 1242: rte->subquery = fireRIRrules(rte->subquery, activeRIRs); 1.81 tgl 1243: continue; 1244: } 1245: 1246: /* 1.99 tgl 1247: * Joins and other non-relation RTEs can be ignored completely. 1248: */ 1249: if (rte->rtekind != RTE_RELATION) 1250: continue; 1251: 1252: /* 1.72 tgl 1253: * If the table is not referenced in the query, then we ignore it. 1254: * This prevents infinite expansion loop due to new rtable entries 1255: * inserted by expansion of a rule. A table is referenced if it is 1.158 momjian 1256: * part of the join set (a source table), or is referenced by any Var 1257: * nodes, or is the result table. 1.60 tgl 1258: */ 1.152 tgl 1259: if (rt_index != parsetree->resultRelation && 1260: !rangeTableEntry_used((Node *) parsetree, rt_index, 0)) 1.22 momjian 1261: continue; 1.45 momjian 1262: 1.83 tgl 1263: /* 1.153 tgl 1264: * We can use NoLock here since either the parser or 1265: * AcquireRewriteLocks should have locked the rel already. 1.83 tgl 1266: */ 1.153 tgl 1267: rel = heap_open(rte->relid, NoLock); 1.92 tgl 1268: 1269: /* 1270: * Collect the RIR rules that we must apply 1271: */ 1.60 tgl 1272: rules = rel->rd_rules; 1273: if (rules == NULL) 1.45 momjian 1274: { 1.83 tgl 1275: heap_close(rel, NoLock); 1.22 momjian 1276: continue; 1277: } 1.60 tgl 1278: locks = NIL; 1.45 momjian 1279: for (i = 0; i < rules->numLocks; i++) 1280: { 1.22 momjian 1281: rule = rules->rules[i]; 1282: if (rule->event != CMD_SELECT) 1283: continue; 1.45 momjian 1284: 1.60 tgl 1285: if (rule->attrno > 0) 1286: { 1287: /* per-attr rule; do we need it? */ 1.80 tgl 1288: if (!attribute_used((Node *) parsetree, rt_index, 1.71 momjian 1289: rule->attrno, 0)) 1.60 tgl 1290: continue; 1291: } 1.22 momjian 1292: 1293: locks = lappend(locks, rule); 1294: } 1295: 1296: /* 1.118 tgl 1297: * If we found any, apply them --- but first check for recursion! 1.22 momjian 1298: */ 1.118 tgl 1299: if (locks != NIL) 1.45 momjian 1300: { 1.136 neilc 1301: ListCell *l; 1.118 tgl 1302: 1.138 neilc 1303: if (list_member_oid(activeRIRs, RelationGetRelid(rel))) 1.124 tgl 1304: ereport(ERROR, 1305: (errcode(ERRCODE_INVALID_OBJECT_DEFINITION), 1306: errmsg("infinite recursion detected in rules for relation \"%s\"", 1307: RelationGetRelationName(rel)))); 1.138 neilc 1308: activeRIRs = lcons_oid(RelationGetRelid(rel), activeRIRs); 1.118 tgl 1309: 1310: foreach(l, locks) 1311: { 1312: rule = lfirst(l); 1.22 momjian 1313: 1.118 tgl 1314: parsetree = ApplyRetrieveRule(parsetree, 1315: rule, 1316: rt_index, 1317: rule->attrno == -1, 1318: rel, 1.137 tgl 1319: activeRIRs); 1.118 tgl 1320: } 1.137 tgl 1321: 1322: activeRIRs = list_delete_first(activeRIRs); 1.4 momjian 1323: } 1.22 momjian 1324: 1.83 tgl 1325: heap_close(rel, NoLock); 1.22 momjian 1326: } 1327: 1.81 tgl 1328: /* 1.158 momjian 1329: * Recurse into sublink subqueries, too. But we already did the ones in 1330: * the rtable. 1.81 tgl 1331: */ 1332: if (parsetree->hasSubLinks) 1.118 tgl 1333: query_tree_walker(parsetree, fireRIRonSubLink, (void *) activeRIRs, 1.116 tgl 1334: QTW_IGNORE_RT_SUBQUERIES); 1.81 tgl 1335: 1.22 momjian 1336: return parsetree; 1337: } 1338: 1339: 1340: /* 1.113 tgl 1341: * Modify the given query by adding 'AND rule_qual IS NOT TRUE' to its 1342: * qualification. This is used to generate suitable "else clauses" for 1343: * conditional INSTEAD rules. (Unfortunately we must use "x IS NOT TRUE", 1344: * not just "NOT x" which the planner is much smarter about, else we will 1345: * do the wrong thing when the qual evaluates to NULL.) 1.84 tgl 1346: * 1.90 momjian 1347: * The rule_qual may contain references to OLD or NEW. OLD references are 1.84 tgl 1348: * replaced by references to the specified rt_index (the relation that the 1349: * rule applies to). NEW references are only possible for INSERT and UPDATE 1350: * queries on the relation itself, and so they should be replaced by copies 1351: * of the related entries in the query's own targetlist. 1352: */ 1.5 momjian 1353: static Query * 1.113 tgl 1354: CopyAndAddInvertedQual(Query *parsetree, 1355: Node *rule_qual, 1356: int rt_index, 1357: CmdType event) 1.4 momjian 1358: { 1.153 tgl 1359: /* Don't scribble on the passed qual (it's in the relcache!) */ 1.84 tgl 1360: Node *new_qual = (Node *) copyObject(rule_qual); 1.4 momjian 1361: 1.153 tgl 1362: /* 1363: * In case there are subqueries in the qual, acquire necessary locks and 1364: * fix any deleted JOIN RTE entries. (This is somewhat redundant with 1.158 momjian 1365: * rewriteRuleAction, but not entirely ... consider restructuring so that 1366: * we only need to process the qual this way once.) 1.153 tgl 1367: */ 1368: (void) acquireLocksOnSubLinks(new_qual, NULL); 1369: 1.84 tgl 1370: /* Fix references to OLD */ 1371: ChangeVarNodes(new_qual, PRS2_OLD_VARNO, rt_index, 0); 1372: /* Fix references to NEW */ 1373: if (event == CMD_INSERT || event == CMD_UPDATE) 1374: new_qual = ResolveNew(new_qual, 1375: PRS2_NEW_VARNO, 1376: 0, 1.154 tgl 1377: rt_fetch(rt_index, parsetree->rtable), 1.84 tgl 1378: parsetree->targetList, 1379: event, 1380: rt_index); 1381: /* And attach the fixed qual */ 1.153 tgl 1382: AddInvertedQual(parsetree, new_qual); 1.4 momjian 1383: 1.153 tgl 1384: return parsetree; 1.1 scrappy 1385: } 1386: 1387: 1388: /* 1.4 momjian 1389: * fireRules - 1.18 scrappy 1390: * Iterate through rule locks applying rules. 1.21 momjian 1391: * 1.112 tgl 1392: * Input arguments: 1393: * parsetree - original query 1394: * rt_index - RT index of result relation in original query 1395: * event - type of rule event 1396: * locks - list of rules to fire 1397: * Output arguments: 1398: * *instead_flag - set TRUE if any unqualified INSTEAD rule is found 1399: * (must be initialized to FALSE) 1.166 tgl 1400: * *returning_flag - set TRUE if we rewrite RETURNING clause in any rule 1401: * (must be initialized to FALSE) 1.112 tgl 1402: * *qual_product - filled with modified original query if any qualified 1403: * INSTEAD rule is found (must be initialized to NULL) 1404: * Return value: 1405: * list of rule actions adjusted for use with this query 1.1 scrappy 1406: * 1.112 tgl 1407: * Qualified INSTEAD rules generate their action with the qualification 1408: * condition added. They also generate a modified version of the original 1409: * query with the negated qualification added, so that it will run only for 1410: * rows that the qualified action doesn't act on. (If there are multiple 1411: * qualified INSTEAD rules, we AND all the negated quals onto a single 1412: * modified original query.) We won't execute the original, unmodified 1.126 momjian 1413: * query if we find either qualified or unqualified INSTEAD rules. If 1.112 tgl 1414: * we find both, the modified original query is discarded too. 1.1 scrappy 1415: */ 1.5 momjian 1416: static List * 1.6 momjian 1417: fireRules(Query *parsetree, 1.4 momjian 1418: int rt_index, 1419: CmdType event, 1.112 tgl 1420: List *locks, 1.6 momjian 1421: bool *instead_flag, 1.166 tgl 1422: bool *returning_flag, 1.112 tgl 1423: Query **qual_product) 1.4 momjian 1424: { 1.5 momjian 1425: List *results = NIL; 1.136 neilc 1426: ListCell *l; 1.4 momjian 1427: 1.136 neilc 1428: foreach(l, locks) 1.4 momjian 1429: { 1.136 neilc 1430: RewriteRule *rule_lock = (RewriteRule *) lfirst(l); 1.112 tgl 1431: Node *event_qual = rule_lock->qual; 1432: List *actions = rule_lock->actions; 1.126 momjian 1433: QuerySource qsrc; 1.136 neilc 1434: ListCell *r; 1.4 momjian 1435: 1.111 tgl 1436: /* Determine correct QuerySource value for actions */ 1437: if (rule_lock->isInstead) 1438: { 1439: if (event_qual != NULL) 1440: qsrc = QSRC_QUAL_INSTEAD_RULE; 1441: else 1.112 tgl 1442: { 1.111 tgl 1443: qsrc = QSRC_INSTEAD_RULE; 1.126 momjian 1444: *instead_flag = true; /* report unqualified INSTEAD */ 1.112 tgl 1445: } 1.111 tgl 1446: } 1447: else 1448: qsrc = QSRC_NON_INSTEAD_RULE; 1449: 1450: if (qsrc == QSRC_QUAL_INSTEAD_RULE) 1.21 momjian 1451: { 1.91 momjian 1452: /* 1.158 momjian 1453: * If there are INSTEAD rules with qualifications, the original 1454: * query is still performed. But all the negated rule 1455: * qualifications of the INSTEAD rules are added so it does its 1456: * actions only in cases where the rule quals of all INSTEAD rules 1457: * are false. Think of it as the default action in a case. We save 1458: * this in *qual_product so RewriteQuery() can add it to the query 1459: * list after we mangled it up enough. 1.112 tgl 1460: * 1.126 momjian 1461: * If we have already found an unqualified INSTEAD rule, then 1462: * *qual_product won't be used, so don't bother building it. 1.18 scrappy 1463: */ 1.126 momjian 1464: if (!*instead_flag) 1.112 tgl 1465: { 1466: if (*qual_product == NULL) 1.153 tgl 1467: *qual_product = copyObject(parsetree); 1.113 tgl 1468: *qual_product = CopyAndAddInvertedQual(*qual_product, 1469: event_qual, 1470: rt_index, 1471: event); 1.112 tgl 1472: } 1.18 scrappy 1473: } 1474: 1.111 tgl 1475: /* Now process the rule's actions and add them to the result list */ 1.4 momjian 1476: foreach(r, actions) 1477: { 1.5 momjian 1478: Query *rule_action = lfirst(r); 1.4 momjian 1479: 1.18 scrappy 1480: if (rule_action->commandType == CMD_NOTHING) 1481: continue; 1.25 momjian 1482: 1.95 tgl 1483: rule_action = rewriteRuleAction(parsetree, rule_action, 1.166 tgl 1484: event_qual, rt_index, event, 1485: returning_flag); 1.4 momjian 1486: 1.111 tgl 1487: rule_action->querySource = qsrc; 1.120 tgl 1488: rule_action->canSetTag = false; /* might change later */ 1.111 tgl 1489: 1.95 tgl 1490: results = lappend(results, rule_action); 1.4 momjian 1491: } 1492: } 1.111 tgl 1493: 1.4 momjian 1494: return results; 1495: } 1496: 1.18 scrappy 1497: 1.112 tgl 1498: /* 1.118 tgl 1499: * RewriteQuery - 1500: * rewrites the query and apply the rules again on the queries rewritten 1.112 tgl 1501: * 1.118 tgl 1502: * rewrite_events is a list of open query-rewrite actions, so we can detect 1503: * infinite recursion. 1.112 tgl 1504: */ 1.5 momjian 1505: static List * 1.118 tgl 1506: RewriteQuery(Query *parsetree, List *rewrite_events) 1.4 momjian 1507: { 1.118 tgl 1508: CmdType event = parsetree->commandType; 1509: bool instead = false; 1.166 tgl 1510: bool returning = false; 1.118 tgl 1511: Query *qual_product = NULL; 1512: List *rewritten = NIL; 1.1 scrappy 1513: 1.22 momjian 1514: /* 1.118 tgl 1515: * If the statement is an update, insert or delete - fire rules on it. 1516: * 1.158 momjian 1517: * SELECT rules are handled later when we have all the queries that should 1518: * get executed. Also, utilities aren't rewritten at all (do we still 1519: * need that check?) 1.22 momjian 1520: */ 1.118 tgl 1521: if (event != CMD_SELECT && event != CMD_UTILITY) 1.22 momjian 1522: { 1.118 tgl 1523: int result_relation; 1524: RangeTblEntry *rt_entry; 1525: Relation rt_entry_relation; 1526: List *locks; 1.22 momjian 1527: 1.118 tgl 1528: result_relation = parsetree->resultRelation; 1529: Assert(result_relation != 0); 1530: rt_entry = rt_fetch(result_relation, parsetree->rtable); 1531: Assert(rt_entry->rtekind == RTE_RELATION); 1.1 scrappy 1532: 1.118 tgl 1533: /* 1.153 tgl 1534: * We can use NoLock here since either the parser or 1535: * AcquireRewriteLocks should have locked the rel already. 1.118 tgl 1536: */ 1.153 tgl 1537: rt_entry_relation = heap_open(rt_entry->relid, NoLock); 1.77 tgl 1538: 1.118 tgl 1539: /* 1.158 momjian 1540: * If it's an INSERT or UPDATE, rewrite the targetlist into standard 1541: * form. This will be needed by the planner anyway, and doing it now 1542: * ensures that any references to NEW.field will behave sanely. 1.118 tgl 1543: */ 1.165 joe 1544: if (event == CMD_UPDATE) 1545: rewriteTargetList(parsetree, rt_entry_relation, NULL); 1546: else if (event == CMD_INSERT) 1547: { 1548: RangeTblEntry *values_rte = NULL; 1549: 1550: /* 1.167 momjian 1551: * If it's an INSERT ... VALUES (...), (...), ... there will be a 1552: * single RTE for the VALUES targetlists. 1.165 joe 1553: */ 1554: if (list_length(parsetree->jointree->fromlist) == 1) 1555: { 1556: RangeTblRef *rtr = (RangeTblRef *) linitial(parsetree->jointree->fromlist); 1557: 1558: if (IsA(rtr, RangeTblRef)) 1559: { 1560: RangeTblEntry *rte = rt_fetch(rtr->rtindex, 1561: parsetree->rtable); 1562: 1563: if (rte->rtekind == RTE_VALUES) 1564: values_rte = rte; 1565: } 1566: } 1567: 1568: if (values_rte) 1569: { 1.167 momjian 1570: List *attrnos; 1.165 joe 1571: 1572: /* Process the main targetlist ... */ 1573: rewriteTargetList(parsetree, rt_entry_relation, &attrnos); 1574: /* ... and the VALUES expression lists */ 1575: rewriteValuesRTE(values_rte, rt_entry_relation, attrnos); 1576: } 1577: else 1578: { 1579: /* Process just the main targetlist */ 1580: rewriteTargetList(parsetree, rt_entry_relation, NULL); 1581: } 1582: } 1.10 momjian 1583: 1.118 tgl 1584: /* 1585: * Collect and apply the appropriate rules. 1586: */ 1587: locks = matchLocks(event, rt_entry_relation->rd_rules, 1588: result_relation, parsetree); 1.1 scrappy 1589: 1.118 tgl 1590: if (locks != NIL) 1591: { 1592: List *product_queries; 1.1 scrappy 1593: 1.118 tgl 1594: product_queries = fireRules(parsetree, 1595: result_relation, 1596: event, 1597: locks, 1598: &instead, 1.166 tgl 1599: &returning, 1.118 tgl 1600: &qual_product); 1.1 scrappy 1601: 1.118 tgl 1602: /* 1.158 momjian 1603: * If we got any product queries, recursively rewrite them --- but 1604: * first check for recursion! 1.118 tgl 1605: */ 1606: if (product_queries != NIL) 1607: { 1.144 momjian 1608: ListCell *n; 1609: rewrite_event *rev; 1.4 momjian 1610: 1.118 tgl 1611: foreach(n, rewrite_events) 1612: { 1613: rev = (rewrite_event *) lfirst(n); 1614: if (rev->relation == RelationGetRelid(rt_entry_relation) && 1615: rev->event == event) 1.124 tgl 1616: ereport(ERROR, 1.158 momjian 1617: (errcode(ERRCODE_INVALID_OBJECT_DEFINITION), 1618: errmsg("infinite recursion detected in rules for relation \"%s\"", 1619: RelationGetRelationName(rt_entry_relation)))); 1.118 tgl 1620: } 1621: 1622: rev = (rewrite_event *) palloc(sizeof(rewrite_event)); 1623: rev->relation = RelationGetRelid(rt_entry_relation); 1624: rev->event = event; 1625: rewrite_events = lcons(rev, rewrite_events); 1626: 1627: foreach(n, product_queries) 1628: { 1629: Query *pt = (Query *) lfirst(n); 1630: List *newstuff; 1631: 1632: newstuff = RewriteQuery(pt, rewrite_events); 1.138 neilc 1633: rewritten = list_concat(rewritten, newstuff); 1.118 tgl 1634: } 1.146 tgl 1635: 1636: rewrite_events = list_delete_first(rewrite_events); 1.118 tgl 1637: } 1638: } 1.4 momjian 1639: 1.166 tgl 1640: /* 1.167 momjian 1641: * If there is an INSTEAD, and the original query has a RETURNING, we 1642: * have to have found a RETURNING in the rule(s), else fail. (Because 1643: * DefineQueryRewrite only allows RETURNING in unconditional INSTEAD 1644: * rules, there's no need to worry whether the substituted RETURNING 1645: * will actually be executed --- it must be.) 1.166 tgl 1646: */ 1647: if ((instead || qual_product != NULL) && 1648: parsetree->returningList && 1649: !returning) 1650: { 1651: switch (event) 1652: { 1653: case CMD_INSERT: 1654: ereport(ERROR, 1655: (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), 1.168 petere 1656: errmsg("cannot perform INSERT RETURNING on relation \"%s\"", 1.167 momjian 1657: RelationGetRelationName(rt_entry_relation)), 1.166 tgl 1658: errhint("You need an unconditional ON INSERT DO INSTEAD rule with a RETURNING clause."))); 1659: break; 1660: case CMD_UPDATE: 1661: ereport(ERROR, 1662: (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), 1.168 petere 1663: errmsg("cannot perform UPDATE RETURNING on relation \"%s\"", 1.167 momjian 1664: RelationGetRelationName(rt_entry_relation)), 1.166 tgl 1665: errhint("You need an unconditional ON UPDATE DO INSTEAD rule with a RETURNING clause."))); 1666: break; 1667: case CMD_DELETE: 1668: ereport(ERROR, 1669: (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), 1.168 petere 1670: errmsg("cannot perform DELETE RETURNING on relation \"%s\"", 1.167 momjian 1671: RelationGetRelationName(rt_entry_relation)), 1.166 tgl 1672: errhint("You need an unconditional ON DELETE DO INSTEAD rule with a RETURNING clause."))); 1673: break; 1674: default: 1675: elog(ERROR, "unrecognized commandType: %d", 1676: (int) event); 1677: break; 1678: } 1679: } 1680: 1.153 tgl 1681: heap_close(rt_entry_relation, NoLock); 1.4 momjian 1682: } 1.18 scrappy 1683: 1.91 momjian 1684: /* 1.158 momjian 1685: * For INSERTs, the original query is done first; for UPDATE/DELETE, it is 1686: * done last. This is needed because update and delete rule actions might 1687: * not do anything if they are invoked after the update or delete is 1688: * performed. The command counter increment between the query executions 1689: * makes the deleted (and maybe the updated) tuples disappear so the scans 1690: * for them in the rule actions cannot find them. 1.112 tgl 1691: * 1.126 momjian 1692: * If we found any unqualified INSTEAD, the original query is not done at 1693: * all, in any form. Otherwise, we add the modified form if qualified 1694: * INSTEADs were found, else the unmodified form. 1.18 scrappy 1695: */ 1.112 tgl 1696: if (!instead) 1.97 tgl 1697: { 1.112 tgl 1698: if (parsetree->commandType == CMD_INSERT) 1699: { 1700: if (qual_product != NULL) 1701: rewritten = lcons(qual_product, rewritten); 1702: else 1703: rewritten = lcons(parsetree, rewritten); 1704: } 1705: else 1706: { 1707: if (qual_product != NULL) 1708: rewritten = lappend(rewritten, qual_product); 1709: else 1710: rewritten = lappend(rewritten, parsetree); 1711: } 1.97 tgl 1712: } 1.4 momjian 1713: 1714: return rewritten; 1.12 scrappy 1715: } 1.22 momjian 1716: 1717: 1718: /* 1.82 tgl 1719: * QueryRewrite - 1720: * Primary entry point to the query rewriter. 1721: * Rewrite one query via query rewrite system, possibly returning 0 1722: * or many queries. 1723: * 1.153 tgl 1724: * NOTE: the parsetree must either have come straight from the parser, 1725: * or have been scanned by AcquireRewriteLocks to acquire suitable locks. 1.22 momjian 1726: */ 1.82 tgl 1727: List * 1728: QueryRewrite(Query *parsetree) 1.22 momjian 1729: { 1.45 momjian 1730: List *querylist; 1731: List *results = NIL; 1.136 neilc 1732: ListCell *l; 1.120 tgl 1733: CmdType origCmdType; 1734: bool foundOriginalQuery; 1735: Query *lastInstead; 1.22 momjian 1736: 1737: /* 1738: * Step 1 1739: * 1740: * Apply all non-SELECT rules possibly getting 0 or many queries 1741: */ 1.118 tgl 1742: querylist = RewriteQuery(parsetree, NIL); 1.22 momjian 1743: 1744: /* 1.62 tgl 1745: * Step 2 1.22 momjian 1746: * 1747: * Apply all the RIR rules on each query 1748: */ 1.45 momjian 1749: foreach(l, querylist) 1750: { 1.90 momjian 1751: Query *query = (Query *) lfirst(l); 1.45 momjian 1752: 1.118 tgl 1753: query = fireRIRrules(query, NIL); 1.71 momjian 1754: 1.45 momjian 1755: /* 1.82 tgl 1756: * If the query target was rewritten as a view, complain. 1.45 momjian 1757: */ 1.82 tgl 1758: if (query->resultRelation) 1.45 momjian 1759: { 1.82 tgl 1760: RangeTblEntry *rte = rt_fetch(query->resultRelation, 1761: query->rtable); 1762: 1.99 tgl 1763: if (rte->rtekind == RTE_SUBQUERY) 1.82 tgl 1764: { 1765: switch (query->commandType) 1766: { 1767: case CMD_INSERT: 1.124 tgl 1768: ereport(ERROR, 1769: (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), 1770: errmsg("cannot insert into a view"), 1771: errhint("You need an unconditional ON INSERT DO INSTEAD rule."))); 1.82 tgl 1772: break; 1773: case CMD_UPDATE: 1.124 tgl 1774: ereport(ERROR, 1775: (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), 1776: errmsg("cannot update a view"), 1777: errhint("You need an unconditional ON UPDATE DO INSTEAD rule."))); 1.82 tgl 1778: break; 1779: case CMD_DELETE: 1.124 tgl 1780: ereport(ERROR, 1781: (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), 1782: errmsg("cannot delete from a view"), 1783: errhint("You need an unconditional ON DELETE DO INSTEAD rule."))); 1.82 tgl 1784: break; 1785: default: 1.124 tgl 1786: elog(ERROR, "unrecognized commandType: %d", 1.82 tgl 1787: (int) query->commandType); 1788: break; 1789: } 1.45 momjian 1790: } 1791: } 1792: 1.82 tgl 1793: results = lappend(results, query); 1.45 momjian 1794: } 1.120 tgl 1795: 1796: /* 1797: * Step 3 1798: * 1.159 momjian 1799: * Determine which, if any, of the resulting queries is supposed to set 1800: * the command-result tag; and update the canSetTag fields accordingly. 1.120 tgl 1801: * 1802: * If the original query is still in the list, it sets the command tag. 1.158 momjian 1803: * Otherwise, the last INSTEAD query of the same kind as the original is 1804: * allowed to set the tag. (Note these rules can leave us with no query 1805: * setting the tag. The tcop code has to cope with this by setting up a 1806: * default tag based on the original un-rewritten query.) 1.120 tgl 1807: * 1808: * The Asserts verify that at most one query in the result list is marked 1.158 momjian 1809: * canSetTag. If we aren't checking asserts, we can fall out of the loop 1810: * as soon as we find the original query. 1.120 tgl 1811: */ 1812: origCmdType = parsetree->commandType; 1813: foundOriginalQuery = false; 1814: lastInstead = NULL; 1815: 1816: foreach(l, results) 1817: { 1818: Query *query = (Query *) lfirst(l); 1819: 1820: if (query->querySource == QSRC_ORIGINAL) 1821: { 1822: Assert(query->canSetTag); 1823: Assert(!foundOriginalQuery); 1824: foundOriginalQuery = true; 1825: #ifndef USE_ASSERT_CHECKING 1826: break; 1827: #endif 1828: } 1829: else 1830: { 1831: Assert(!query->canSetTag); 1832: if (query->commandType == origCmdType && 1833: (query->querySource == QSRC_INSTEAD_RULE || 1834: query->querySource == QSRC_QUAL_INSTEAD_RULE)) 1835: lastInstead = query; 1836: } 1837: } 1838: 1839: if (!foundOriginalQuery && lastInstead != NULL) 1840: lastInstead->canSetTag = true; 1.45 momjian 1841: 1.82 tgl 1842: return results; 1.22 momjian 1843: }
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