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Annotation of pgsql/src/backend/rewrite/rewriteHandler.c, revision 1.155
1.1 scrappy 1: /*------------------------------------------------------------------------- 2: * 1.35 momjian 3: * rewriteHandler.c 1.95 tgl 4: * Primary module of query rewriter. 1.1 scrappy 5: * 1.147 pgsql 6: * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group 1.66 momjian 7: * Portions Copyright (c) 1994, Regents of the University of California 1.1 scrappy 8: * 9: * IDENTIFICATION 1.155 ! tgl 10: * $PostgreSQL: pgsql/src/backend/rewrite/rewriteHandler.c,v 1.154 2005/06/04 19:19:42 tgl Exp $ 1.1 scrappy 11: * 12: *------------------------------------------------------------------------- 13: */ 14: #include "postgres.h" 1.53 momjian 15: 16: #include "access/heapam.h" 1.55 tgl 17: #include "catalog/pg_operator.h" 1.53 momjian 18: #include "catalog/pg_type.h" 19: #include "miscadmin.h" 1.55 tgl 20: #include "nodes/makefuncs.h" 1.47 tgl 21: #include "optimizer/clauses.h" 1.28 momjian 22: #include "optimizer/prep.h" 1.70 tgl 23: #include "optimizer/var.h" 1.53 momjian 24: #include "parser/analyze.h" 1.101 tgl 25: #include "parser/parse_coerce.h" 1.55 tgl 26: #include "parser/parse_expr.h" 27: #include "parser/parse_oper.h" 1.101 tgl 28: #include "parser/parse_type.h" 1.53 momjian 29: #include "parser/parsetree.h" 1.95 tgl 30: #include "rewrite/rewriteHandler.h" 1.1 scrappy 31: #include "rewrite/rewriteManip.h" 1.101 tgl 32: #include "utils/builtins.h" 1.22 momjian 33: #include "utils/lsyscache.h" 34: 35: 1.118 tgl 36: /* We use a list of these to detect recursion in RewriteQuery */ 1.126 momjian 37: typedef struct rewrite_event 38: { 1.118 tgl 39: Oid relation; /* OID of relation having rules */ 40: CmdType event; /* type of rule being fired */ 1.128 momjian 41: } rewrite_event; 1.118 tgl 42: 1.153 tgl 43: static bool acquireLocksOnSubLinks(Node *node, void *context); 1.95 tgl 44: static Query *rewriteRuleAction(Query *parsetree, 1.98 momjian 45: Query *rule_action, 46: Node *rule_qual, 47: int rt_index, 48: CmdType event); 1.89 tgl 49: static List *adjustJoinTreeList(Query *parsetree, bool removert, int rt_index); 1.101 tgl 50: static void rewriteTargetList(Query *parsetree, Relation target_relation); 51: static TargetEntry *process_matched_tle(TargetEntry *src_tle, 1.144 momjian 52: TargetEntry *prior_tle, 53: const char *attrName); 1.139 tgl 54: static Node *get_assignment_input(Node *node); 1.151 tgl 55: static void markQueryForLocking(Query *qry, bool forUpdate, bool skipOldNew); 1.81 tgl 56: static List *matchLocks(CmdType event, RuleLock *rulelocks, 1.90 momjian 57: int varno, Query *parsetree); 1.118 tgl 58: static Query *fireRIRrules(Query *parsetree, List *activeRIRs); 1.82 tgl 59: 1.1 scrappy 60: 61: /* 1.153 tgl 62: * AcquireRewriteLocks - 63: * Acquire suitable locks on all the relations mentioned in the Query. 64: * These locks will ensure that the relation schemas don't change under us 65: * while we are rewriting and planning the query. 66: * 67: * A secondary purpose of this routine is to fix up JOIN RTE references to 68: * dropped columns (see details below). Because the RTEs are modified in 69: * place, it is generally appropriate for the caller of this routine to have 70: * first done a copyObject() to make a writable copy of the querytree in the 71: * current memory context. 72: * 73: * This processing can, and for efficiency's sake should, be skipped when the 74: * querytree has just been built by the parser: parse analysis already got 75: * all the same locks we'd get here, and the parser will have omitted dropped 76: * columns from JOINs to begin with. But we must do this whenever we are 77: * dealing with a querytree produced earlier than the current command. 78: * 79: * About JOINs and dropped columns: although the parser never includes an 80: * already-dropped column in a JOIN RTE's alias var list, it is possible for 81: * such a list in a stored rule to include references to dropped columns. 82: * (If the column is not explicitly referenced anywhere else in the query, 83: * the dependency mechanism won't consider it used by the rule and so won't 84: * prevent the column drop.) To support get_rte_attribute_is_dropped(), 85: * we replace join alias vars that reference dropped columns with NULL Const 86: * nodes. 87: * 88: * (In PostgreSQL 8.0, we did not do this processing but instead had 89: * get_rte_attribute_is_dropped() recurse to detect dropped columns in joins. 90: * That approach had horrible performance unfortunately; in particular 91: * construction of a nested join was O(N^2) in the nesting depth.) 92: */ 93: void 94: AcquireRewriteLocks(Query *parsetree) 95: { 96: ListCell *l; 97: int rt_index; 98: 99: /* 100: * First, process RTEs of the current query level. 101: */ 102: rt_index = 0; 103: foreach(l, parsetree->rtable) 104: { 105: RangeTblEntry *rte = (RangeTblEntry *) lfirst(l); 106: Relation rel; 107: LOCKMODE lockmode; 108: List *newaliasvars; 1.154 tgl 109: Index curinputvarno; 110: RangeTblEntry *curinputrte; 1.153 tgl 111: ListCell *ll; 112: 113: ++rt_index; 114: switch (rte->rtekind) 115: { 116: case RTE_RELATION: 117: /* 118: * Grab the appropriate lock type for the relation, and 119: * do not release it until end of transaction. This protects 120: * the rewriter and planner against schema changes mid-query. 121: * 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 126: * would be trying to upgrade the lock, leading to possible 127: * deadlocks. 128: */ 129: if (rt_index == parsetree->resultRelation) 130: lockmode = RowExclusiveLock; 131: else if (list_member_int(parsetree->rowMarks, rt_index)) 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: 141: /* 142: * Scan the join's alias var list to see if any columns 143: * have been dropped, and if so replace those Vars with 144: * NULL Consts. 1.154 tgl 145: * 146: * Since a join has only two inputs, we can expect to 147: * see multiple references to the same input RTE; optimize 148: * away multiple fetches. 1.153 tgl 149: */ 150: newaliasvars = NIL; 1.154 tgl 151: curinputvarno = 0; 152: curinputrte = NULL; 1.153 tgl 153: foreach(ll, rte->joinaliasvars) 154: { 155: Var *aliasvar = (Var *) lfirst(ll); 156: 157: /* 158: * If the list item isn't a simple Var, then it must 159: * represent a merged column, ie a USING column, and so it 160: * couldn't possibly be dropped, since it's referenced in 161: * the join clause. (Conceivably it could also be a 162: * NULL constant already? But that's OK too.) 163: */ 164: if (IsA(aliasvar, Var)) 165: { 166: /* 167: * The elements of an alias list have to refer to 168: * earlier RTEs of the same rtable, because that's 169: * the order the planner builds things in. So we 170: * already processed the referenced RTE, and so it's 171: * safe to use get_rte_attribute_is_dropped on it. 172: * (This might not hold after rewriting or planning, 173: * but it's OK to assume here.) 174: */ 175: Assert(aliasvar->varlevelsup == 0); 1.154 tgl 176: if (aliasvar->varno != curinputvarno) 177: { 178: curinputvarno = aliasvar->varno; 179: if (curinputvarno >= rt_index) 180: elog(ERROR, "unexpected varno %d in JOIN RTE %d", 181: curinputvarno, rt_index); 182: curinputrte = rt_fetch(curinputvarno, 183: parsetree->rtable); 184: } 185: if (get_rte_attribute_is_dropped(curinputrte, 186: aliasvar->varattno)) 1.153 tgl 187: { 188: /* 189: * can't use vartype here, since that might be a 190: * now-dropped type OID, but it doesn't really 191: * matter what type the Const claims to be. 192: */ 193: aliasvar = (Var *) makeNullConst(INT4OID); 194: } 195: } 196: newaliasvars = lappend(newaliasvars, aliasvar); 197: } 198: rte->joinaliasvars = newaliasvars; 199: break; 200: 201: case RTE_SUBQUERY: 202: /* 203: * The subquery RTE itself is all right, but we have to 204: * recurse to process the represented subquery. 205: */ 206: AcquireRewriteLocks(rte->subquery); 207: break; 208: 209: default: 210: /* ignore other types of RTEs */ 211: break; 212: } 213: } 214: 215: /* 216: * Recurse into sublink subqueries, too. But we already did the ones 217: * in the rtable. 218: */ 219: if (parsetree->hasSubLinks) 220: query_tree_walker(parsetree, acquireLocksOnSubLinks, NULL, 221: QTW_IGNORE_RT_SUBQUERIES); 222: } 223: 224: /* 225: * Walker to find sublink subqueries for AcquireRewriteLocks 226: */ 227: static bool 228: acquireLocksOnSubLinks(Node *node, void *context) 229: { 230: if (node == NULL) 231: return false; 232: if (IsA(node, SubLink)) 233: { 234: SubLink *sub = (SubLink *) node; 235: 236: /* Do what we came for */ 237: AcquireRewriteLocks((Query *) sub->subselect); 238: /* Fall through to process lefthand args of SubLink */ 239: } 240: 241: /* 242: * Do NOT recurse into Query nodes, because AcquireRewriteLocks already 243: * processed subselects of subselects for us. 244: */ 245: return expression_tree_walker(node, acquireLocksOnSubLinks, context); 246: } 247: 248: 249: /* 1.95 tgl 250: * rewriteRuleAction - 251: * Rewrite the rule action with appropriate qualifiers (taken from 252: * the triggering query). 1.1 scrappy 253: */ 1.95 tgl 254: static Query * 255: rewriteRuleAction(Query *parsetree, 1.6 momjian 256: Query *rule_action, 257: Node *rule_qual, 1.4 momjian 258: int rt_index, 1.95 tgl 259: CmdType event) 1.4 momjian 260: { 1.95 tgl 261: int current_varno, 262: new_varno; 263: int rt_length; 1.84 tgl 264: Query *sub_action; 265: Query **sub_action_ptr; 1.4 momjian 266: 1.95 tgl 267: /* 268: * Make modifiable copies of rule action and qual (what we're passed 269: * are the stored versions in the relcache; don't touch 'em!). 270: */ 271: rule_action = (Query *) copyObject(rule_action); 272: rule_qual = (Node *) copyObject(rule_qual); 273: 1.153 tgl 274: /* 275: * Acquire necessary locks and fix any deleted JOIN RTE entries. 276: */ 277: AcquireRewriteLocks(rule_action); 278: (void) acquireLocksOnSubLinks(rule_qual, NULL); 279: 1.95 tgl 280: current_varno = rt_index; 1.138 neilc 281: rt_length = list_length(parsetree->rtable); 1.95 tgl 282: new_varno = PRS2_NEW_VARNO + rt_length; 1.84 tgl 283: 284: /* 285: * Adjust rule action and qual to offset its varnos, so that we can 1.94 tgl 286: * merge its rtable with the main parsetree's rtable. 1.84 tgl 287: * 1.90 momjian 288: * If the rule action is an INSERT...SELECT, the OLD/NEW rtable entries 289: * will be in the SELECT part, and we have to modify that rather than 290: * the top-level INSERT (kluge!). 1.84 tgl 291: */ 1.95 tgl 292: sub_action = getInsertSelectQuery(rule_action, &sub_action_ptr); 1.84 tgl 293: 294: OffsetVarNodes((Node *) sub_action, rt_length, 0); 1.95 tgl 295: OffsetVarNodes(rule_qual, rt_length, 0); 1.84 tgl 296: /* but references to *OLD* should point at original rt_index */ 297: ChangeVarNodes((Node *) sub_action, 298: PRS2_OLD_VARNO + rt_length, rt_index, 0); 1.95 tgl 299: ChangeVarNodes(rule_qual, 1.84 tgl 300: PRS2_OLD_VARNO + rt_length, rt_index, 0); 301: 302: /* 1.98 momjian 303: * Generate expanded rtable consisting of main parsetree's rtable plus 304: * rule action's rtable; this becomes the complete rtable for the rule 305: * action. Some of the entries may be unused after we finish 1.132 tgl 306: * rewriting, but we leave them all in place for two reasons: 307: * 1.144 momjian 308: * We'd have a much harder job to adjust the query's varnos if we 309: * selectively removed RT entries. 1.132 tgl 310: * 1.144 momjian 311: * If the rule is INSTEAD, then the original query won't be executed at 312: * all, and so its rtable must be preserved so that the executor will 313: * do the correct permissions checks on it. 1.132 tgl 314: * 315: * RT entries that are not referenced in the completed jointree will be 316: * ignored by the planner, so they do not affect query semantics. But 317: * any permissions checks specified in them will be applied during 1.144 momjian 318: * executor startup (see ExecCheckRTEPerms()). This allows us to 319: * check that the caller has, say, insert-permission on a view, when 320: * the view is not semantically referenced at all in the resulting 321: * query. 1.132 tgl 322: * 323: * When a rule is not INSTEAD, the permissions checks done on its copied 1.144 momjian 324: * RT entries will be redundant with those done during execution of 325: * the original query, but we don't bother to treat that case 326: * differently. 1.84 tgl 327: * 1.94 tgl 328: * NOTE: because planner will destructively alter rtable, we must ensure 1.98 momjian 329: * that rule action's rtable is separate and shares no substructure 330: * with the main rtable. Hence do a deep copy here. 1.94 tgl 331: */ 1.138 neilc 332: sub_action->rtable = list_concat((List *) copyObject(parsetree->rtable), 1.144 momjian 333: sub_action->rtable); 1.84 tgl 334: 335: /* 336: * Each rule action's jointree should be the main parsetree's jointree 1.90 momjian 337: * plus that rule's jointree, but usually *without* the original 338: * rtindex that we're replacing (if present, which it won't be for 339: * INSERT). Note that if the rule action refers to OLD, its jointree 340: * will add a reference to rt_index. If the rule action doesn't refer 341: * to OLD, but either the rule_qual or the user query quals do, then 342: * we need to keep the original rtindex in the jointree to provide 343: * data for the quals. We don't want the original rtindex to be 344: * joined twice, however, so avoid keeping it if the rule action 345: * mentions it. 1.94 tgl 346: * 1.98 momjian 347: * As above, the action's jointree must not share substructure with the 348: * main parsetree's. 1.84 tgl 349: */ 1.123 tgl 350: if (sub_action->commandType != CMD_UTILITY) 1.84 tgl 351: { 1.90 momjian 352: bool keeporig; 353: List *newjointree; 1.84 tgl 354: 1.123 tgl 355: Assert(sub_action->jointree != NULL); 1.90 momjian 356: keeporig = (!rangeTableEntry_used((Node *) sub_action->jointree, 357: rt_index, 0)) && 1.95 tgl 358: (rangeTableEntry_used(rule_qual, rt_index, 0) || 1.98 momjian 359: rangeTableEntry_used(parsetree->jointree->quals, rt_index, 0)); 1.89 tgl 360: newjointree = adjustJoinTreeList(parsetree, !keeporig, rt_index); 1.123 tgl 361: if (newjointree != NIL) 362: { 363: /* 364: * If sub_action is a setop, manipulating its jointree will do 365: * no good at all, because the jointree is dummy. (Perhaps 366: * someday we could push the joining and quals down to the 367: * member statements of the setop?) 368: */ 369: if (sub_action->setOperations != NULL) 1.124 tgl 370: ereport(ERROR, 371: (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), 372: errmsg("conditional UNION/INTERSECT/EXCEPT statements are not implemented"))); 1.123 tgl 373: 374: sub_action->jointree->fromlist = 1.138 neilc 375: list_concat(newjointree, sub_action->jointree->fromlist); 1.123 tgl 376: } 1.84 tgl 377: } 378: 379: /* 1.90 momjian 380: * Event Qualification forces copying of parsetree and splitting into 381: * two queries one w/rule_qual, one w/NOT rule_qual. Also add user 382: * query qual onto rule action 1.84 tgl 383: */ 1.95 tgl 384: AddQual(sub_action, rule_qual); 1.84 tgl 385: 386: AddQual(sub_action, parsetree->jointree->quals); 1.4 momjian 387: 1.84 tgl 388: /* 1.90 momjian 389: * Rewrite new.attribute w/ right hand side of target-list entry for 390: * appropriate field name in insert/update. 1.84 tgl 391: * 392: * KLUGE ALERT: since ResolveNew returns a mutated copy, we can't just 393: * apply it to sub_action; we have to remember to update the sublink 1.95 tgl 394: * inside rule_action, too. 1.84 tgl 395: */ 1.141 tgl 396: if ((event == CMD_INSERT || event == CMD_UPDATE) && 397: sub_action->commandType != CMD_UTILITY) 1.84 tgl 398: { 399: sub_action = (Query *) ResolveNew((Node *) sub_action, 1.95 tgl 400: new_varno, 1.84 tgl 401: 0, 1.154 tgl 402: rt_fetch(new_varno, 403: sub_action->rtable), 1.84 tgl 404: parsetree->targetList, 1.95 tgl 405: event, 406: current_varno); 1.84 tgl 407: if (sub_action_ptr) 408: *sub_action_ptr = sub_action; 409: else 1.95 tgl 410: rule_action = sub_action; 1.4 momjian 411: } 1.84 tgl 412: 1.95 tgl 413: return rule_action; 1.4 momjian 414: } 415: 1.22 momjian 416: /* 1.89 tgl 417: * Copy the query's jointree list, and optionally attempt to remove any 418: * occurrence of the given rt_index as a top-level join item (we do not look 419: * for it within join items; this is OK because we are only expecting to find 420: * it as an UPDATE or DELETE target relation, which will be at the top level 1.94 tgl 421: * of the join). Returns modified jointree list --- this is a separate copy 422: * sharing no nodes with the original. 1.22 momjian 423: */ 1.80 tgl 424: static List * 1.89 tgl 425: adjustJoinTreeList(Query *parsetree, bool removert, int rt_index) 1.71 momjian 426: { 1.94 tgl 427: List *newjointree = copyObject(parsetree->jointree->fromlist); 1.136 neilc 428: ListCell *l; 1.58 tgl 429: 1.89 tgl 430: if (removert) 1.58 tgl 431: { 1.136 neilc 432: foreach(l, newjointree) 1.89 tgl 433: { 1.136 neilc 434: RangeTblRef *rtr = lfirst(l); 1.22 momjian 435: 1.115 tgl 436: if (IsA(rtr, RangeTblRef) && 437: rtr->rtindex == rt_index) 1.89 tgl 438: { 1.138 neilc 439: newjointree = list_delete_ptr(newjointree, rtr); 1.144 momjian 440: 441: /* 442: * foreach is safe because we exit loop after 443: * list_delete... 444: */ 1.89 tgl 445: break; 446: } 1.80 tgl 447: } 1.58 tgl 448: } 1.80 tgl 449: return newjointree; 1.22 momjian 450: } 1.20 momjian 451: 1.4 momjian 452: 1.22 momjian 453: /* 1.101 tgl 454: * rewriteTargetList - rewrite INSERT/UPDATE targetlist into standard form 455: * 456: * This has the following responsibilities: 457: * 458: * 1. For an INSERT, add tlist entries to compute default values for any 459: * attributes that have defaults and are not assigned to in the given tlist. 460: * (We do not insert anything for default-less attributes, however. The 461: * planner will later insert NULLs for them, but there's no reason to slow 1.122 tgl 462: * down rewriter processing with extra tlist nodes.) Also, for both INSERT 463: * and UPDATE, replace explicit DEFAULT specifications with column default 464: * expressions. 1.101 tgl 465: * 466: * 2. Merge multiple entries for the same target attribute, or declare error 1.139 tgl 467: * if we can't. Multiple entries are only allowed for INSERT/UPDATE of 468: * portions of an array or record field, for example 469: * UPDATE table SET foo[2] = 42, foo[4] = 43; 1.101 tgl 470: * We can merge such operations into a single assignment op. Essentially, 471: * the expression we want to produce in this case is like 472: * foo = array_set(array_set(foo, 2, 42), 4, 43) 473: * 474: * 3. Sort the tlist into standard order: non-junk fields in order by resno, 475: * then junk fields (these in no particular order). 476: * 477: * We must do items 1 and 2 before firing rewrite rules, else rewritten 1.108 momjian 478: * references to NEW.foo will produce wrong or incomplete results. Item 3 1.101 tgl 479: * is not needed for rewriting, but will be needed by the planner, and we 480: * can do it essentially for free while handling items 1 and 2. 481: */ 482: static void 483: rewriteTargetList(Query *parsetree, Relation target_relation) 484: { 485: CmdType commandType = parsetree->commandType; 1.149 tgl 486: TargetEntry **new_tles; 1.101 tgl 487: List *new_tlist = NIL; 1.149 tgl 488: List *junk_tlist = NIL; 489: Form_pg_attribute att_tup; 1.101 tgl 490: int attrno, 1.149 tgl 491: next_junk_attrno, 1.101 tgl 492: numattrs; 1.136 neilc 493: ListCell *temp; 1.101 tgl 494: 495: /* 1.149 tgl 496: * We process the normal (non-junk) attributes by scanning the input 497: * tlist once and transferring TLEs into an array, then scanning the 498: * array to build an output tlist. This avoids O(N^2) behavior for 499: * large numbers of attributes. 500: * 501: * Junk attributes are tossed into a separate list during the same 502: * tlist scan, then appended to the reconstructed tlist. 1.101 tgl 503: */ 504: numattrs = RelationGetNumberOfAttributes(target_relation); 1.149 tgl 505: new_tles = (TargetEntry **) palloc0(numattrs * sizeof(TargetEntry *)); 506: next_junk_attrno = numattrs + 1; 1.101 tgl 507: 1.149 tgl 508: foreach(temp, parsetree->targetList) 1.101 tgl 509: { 1.149 tgl 510: TargetEntry *old_tle = (TargetEntry *) lfirst(temp); 511: 1.150 tgl 512: if (!old_tle->resjunk) 1.149 tgl 513: { 514: /* Normal attr: stash it into new_tles[] */ 1.150 tgl 515: attrno = old_tle->resno; 1.149 tgl 516: if (attrno < 1 || attrno > numattrs) 517: elog(ERROR, "bogus resno %d in targetlist", attrno); 518: att_tup = target_relation->rd_att->attrs[attrno - 1]; 1.105 tgl 519: 1.149 tgl 520: /* We can (and must) ignore deleted attributes */ 521: if (att_tup->attisdropped) 522: continue; 1.101 tgl 523: 1.149 tgl 524: /* Merge with any prior assignment to same attribute */ 525: new_tles[attrno - 1] = 526: process_matched_tle(old_tle, 527: new_tles[attrno - 1], 528: NameStr(att_tup->attname)); 529: } 530: else 1.101 tgl 531: { 1.149 tgl 532: /* 533: * Copy all resjunk tlist entries to junk_tlist, and 534: * assign them resnos above the last real resno. 535: * 536: * Typical junk entries include ORDER BY or GROUP BY expressions 537: * (are these actually possible in an INSERT or UPDATE?), system 538: * attribute references, etc. 539: */ 1.101 tgl 540: 1.149 tgl 541: /* Get the resno right, but don't copy unnecessarily */ 1.150 tgl 542: if (old_tle->resno != next_junk_attrno) 1.101 tgl 543: { 1.150 tgl 544: old_tle = flatCopyTargetEntry(old_tle); 545: old_tle->resno = next_junk_attrno; 1.101 tgl 546: } 1.149 tgl 547: junk_tlist = lappend(junk_tlist, old_tle); 548: next_junk_attrno++; 1.101 tgl 549: } 1.149 tgl 550: } 551: 552: for (attrno = 1; attrno <= numattrs; attrno++) 553: { 554: TargetEntry *new_tle = new_tles[attrno - 1]; 555: 556: att_tup = target_relation->rd_att->attrs[attrno - 1]; 557: 558: /* We can (and must) ignore deleted attributes */ 559: if (att_tup->attisdropped) 560: continue; 1.101 tgl 561: 1.122 tgl 562: /* 1.126 momjian 563: * Handle the two cases where we need to insert a default 564: * expression: it's an INSERT and there's no tlist entry for the 565: * column, or the tlist entry is a DEFAULT placeholder node. 1.122 tgl 566: */ 567: if ((new_tle == NULL && commandType == CMD_INSERT) || 1.149 tgl 568: (new_tle && new_tle->expr && IsA(new_tle->expr, SetToDefault))) 1.101 tgl 569: { 570: Node *new_expr; 571: 572: new_expr = build_column_default(target_relation, attrno); 1.122 tgl 573: 574: /* 575: * If there is no default (ie, default is effectively NULL), 576: * we can omit the tlist entry in the INSERT case, since the 577: * planner can insert a NULL for itself, and there's no point 1.126 momjian 578: * in spending any more rewriter cycles on the entry. But in 579: * the UPDATE case we've got to explicitly set the column to 580: * NULL. 1.122 tgl 581: */ 582: if (!new_expr) 583: { 584: if (commandType == CMD_INSERT) 585: new_tle = NULL; 586: else 587: { 588: new_expr = (Node *) makeConst(att_tup->atttypid, 589: att_tup->attlen, 590: (Datum) 0, 591: true, /* isnull */ 592: att_tup->attbyval); 593: /* this is to catch a NOT NULL domain constraint */ 594: new_expr = coerce_to_domain(new_expr, 595: InvalidOid, 596: att_tup->atttypid, 1.140 tgl 597: COERCE_IMPLICIT_CAST, 1.145 tgl 598: false, 1.140 tgl 599: false); 1.122 tgl 600: } 601: } 1.101 tgl 602: 603: if (new_expr) 1.150 tgl 604: new_tle = makeTargetEntry((Expr *) new_expr, 605: attrno, 606: pstrdup(NameStr(att_tup->attname)), 607: false); 1.101 tgl 608: } 609: 610: if (new_tle) 611: new_tlist = lappend(new_tlist, new_tle); 612: } 613: 1.149 tgl 614: pfree(new_tles); 1.101 tgl 615: 1.149 tgl 616: parsetree->targetList = list_concat(new_tlist, junk_tlist); 1.101 tgl 617: } 618: 619: 620: /* 621: * Convert a matched TLE from the original tlist into a correct new TLE. 622: * 623: * This routine detects and handles multiple assignments to the same target 1.129 tgl 624: * attribute. (The attribute name is needed only for error messages.) 1.101 tgl 625: */ 626: static TargetEntry * 627: process_matched_tle(TargetEntry *src_tle, 1.129 tgl 628: TargetEntry *prior_tle, 629: const char *attrName) 1.101 tgl 630: { 1.150 tgl 631: TargetEntry *result; 1.139 tgl 632: Node *src_expr; 633: Node *prior_expr; 634: Node *src_input; 635: Node *prior_input; 1.101 tgl 636: Node *priorbottom; 1.139 tgl 637: Node *newexpr; 1.101 tgl 638: 639: if (prior_tle == NULL) 640: { 641: /* 642: * Normal case where this is the first assignment to the 643: * attribute. 644: */ 645: return src_tle; 646: } 647: 1.139 tgl 648: /*---------- 1.101 tgl 649: * Multiple assignments to same attribute. Allow only if all are 1.139 tgl 650: * FieldStore or ArrayRef assignment operations. This is a bit 651: * tricky because what we may actually be looking at is a nest of 652: * such nodes; consider 653: * UPDATE tab SET col.fld1.subfld1 = x, col.fld2.subfld2 = y 654: * The two expressions produced by the parser will look like 655: * FieldStore(col, fld1, FieldStore(placeholder, subfld1, x)) 656: * FieldStore(col, fld2, FieldStore(placeholder, subfld2, x)) 657: * However, we can ignore the substructure and just consider the top 658: * FieldStore or ArrayRef from each assignment, because it works to 659: * combine these as 660: * FieldStore(FieldStore(col, fld1, 661: * FieldStore(placeholder, subfld1, x)), 662: * fld2, FieldStore(placeholder, subfld2, x)) 663: * Note the leftmost expression goes on the inside so that the 664: * assignments appear to occur left-to-right. 665: * 666: * For FieldStore, instead of nesting we can generate a single 1.144 momjian 667: * FieldStore with multiple target fields. We must nest when 1.139 tgl 668: * ArrayRefs are involved though. 669: *---------- 670: */ 671: src_expr = (Node *) src_tle->expr; 672: prior_expr = (Node *) prior_tle->expr; 673: src_input = get_assignment_input(src_expr); 674: prior_input = get_assignment_input(prior_expr); 675: if (src_input == NULL || 676: prior_input == NULL || 677: exprType(src_expr) != exprType(prior_expr)) 1.124 tgl 678: ereport(ERROR, 679: (errcode(ERRCODE_SYNTAX_ERROR), 1.130 petere 680: errmsg("multiple assignments to same column \"%s\"", 1.129 tgl 681: attrName))); 1.101 tgl 682: 683: /* 1.139 tgl 684: * Prior TLE could be a nest of assignments if we do this more than 1.101 tgl 685: * once. 686: */ 1.139 tgl 687: priorbottom = prior_input; 688: for (;;) 689: { 1.144 momjian 690: Node *newbottom = get_assignment_input(priorbottom); 1.139 tgl 691: 692: if (newbottom == NULL) 693: break; /* found the original Var reference */ 694: priorbottom = newbottom; 695: } 696: if (!equal(priorbottom, src_input)) 1.124 tgl 697: ereport(ERROR, 698: (errcode(ERRCODE_SYNTAX_ERROR), 1.130 petere 699: errmsg("multiple assignments to same column \"%s\"", 1.129 tgl 700: attrName))); 1.101 tgl 701: 702: /* 703: * Looks OK to nest 'em. 704: */ 1.139 tgl 705: if (IsA(src_expr, FieldStore)) 706: { 1.144 momjian 707: FieldStore *fstore = makeNode(FieldStore); 1.139 tgl 708: 709: if (IsA(prior_expr, FieldStore)) 710: { 711: /* combine the two */ 712: memcpy(fstore, prior_expr, sizeof(FieldStore)); 713: fstore->newvals = 714: list_concat(list_copy(((FieldStore *) prior_expr)->newvals), 1.144 momjian 715: list_copy(((FieldStore *) src_expr)->newvals)); 1.139 tgl 716: fstore->fieldnums = 717: list_concat(list_copy(((FieldStore *) prior_expr)->fieldnums), 1.144 momjian 718: list_copy(((FieldStore *) src_expr)->fieldnums)); 1.139 tgl 719: } 720: else 721: { 722: /* general case, just nest 'em */ 723: memcpy(fstore, src_expr, sizeof(FieldStore)); 724: fstore->arg = (Expr *) prior_expr; 725: } 726: newexpr = (Node *) fstore; 727: } 728: else if (IsA(src_expr, ArrayRef)) 729: { 730: ArrayRef *aref = makeNode(ArrayRef); 731: 732: memcpy(aref, src_expr, sizeof(ArrayRef)); 733: aref->refexpr = (Expr *) prior_expr; 734: newexpr = (Node *) aref; 735: } 736: else 737: { 738: elog(ERROR, "can't happen"); 739: newexpr = NULL; 740: } 1.101 tgl 741: 1.150 tgl 742: result = flatCopyTargetEntry(src_tle); 743: result->expr = (Expr *) newexpr; 744: return result; 1.101 tgl 745: } 746: 1.139 tgl 747: /* 748: * If node is an assignment node, return its input; else return NULL 749: */ 750: static Node * 751: get_assignment_input(Node *node) 752: { 753: if (node == NULL) 754: return NULL; 755: if (IsA(node, FieldStore)) 756: { 757: FieldStore *fstore = (FieldStore *) node; 758: 759: return (Node *) fstore->arg; 760: } 761: else if (IsA(node, ArrayRef)) 762: { 763: ArrayRef *aref = (ArrayRef *) node; 764: 765: if (aref->refassgnexpr == NULL) 766: return NULL; 767: return (Node *) aref->refexpr; 768: } 769: return NULL; 770: } 1.101 tgl 771: 772: /* 773: * Make an expression tree for the default value for a column. 774: * 775: * If there is no default, return a NULL instead. 776: */ 1.104 momjian 777: Node * 1.101 tgl 778: build_column_default(Relation rel, int attrno) 779: { 780: TupleDesc rd_att = rel->rd_att; 781: Form_pg_attribute att_tup = rd_att->attrs[attrno - 1]; 782: Oid atttype = att_tup->atttypid; 783: int32 atttypmod = att_tup->atttypmod; 784: Node *expr = NULL; 785: Oid exprtype; 786: 787: /* 788: * Scan to see if relation has a default for this column. 789: */ 790: if (rd_att->constr && rd_att->constr->num_defval > 0) 791: { 792: AttrDefault *defval = rd_att->constr->defval; 793: int ndef = rd_att->constr->num_defval; 794: 795: while (--ndef >= 0) 796: { 797: if (attrno == defval[ndef].adnum) 798: { 799: /* 800: * Found it, convert string representation to node tree. 801: */ 802: expr = stringToNode(defval[ndef].adbin); 803: break; 804: } 805: } 806: } 807: 808: if (expr == NULL) 809: { 810: /* 1.108 momjian 811: * No per-column default, so look for a default for the type 812: * itself. 1.101 tgl 813: */ 1.134 tgl 814: expr = get_typdefault(atttype); 1.101 tgl 815: } 816: 817: if (expr == NULL) 818: return NULL; /* No default anywhere */ 819: 820: /* 1.125 tgl 821: * Make sure the value is coerced to the target column type; this will 822: * generally be true already, but there seem to be some corner cases 1.126 momjian 823: * involving domain defaults where it might not be true. This should 824: * match the parser's processing of non-defaulted expressions --- see 825: * updateTargetListEntry(). 1.101 tgl 826: */ 827: exprtype = exprType(expr); 828: 1.126 momjian 829: expr = coerce_to_target_type(NULL, /* no UNKNOWN params here */ 1.119 tgl 830: expr, exprtype, 1.110 tgl 831: atttype, atttypmod, 832: COERCION_ASSIGNMENT, 833: COERCE_IMPLICIT_CAST); 834: if (expr == NULL) 1.124 tgl 835: ereport(ERROR, 836: (errcode(ERRCODE_DATATYPE_MISMATCH), 837: errmsg("column \"%s\" is of type %s" 838: " but default expression is of type %s", 839: NameStr(att_tup->attname), 840: format_type_be(atttype), 841: format_type_be(exprtype)), 1.126 momjian 842: errhint("You will need to rewrite or cast the expression."))); 1.101 tgl 843: 844: return expr; 845: } 846: 847: 848: /* 1.81 tgl 849: * matchLocks - 850: * match the list of locks and returns the matching rules 1.22 momjian 851: */ 1.81 tgl 852: static List * 853: matchLocks(CmdType event, 854: RuleLock *rulelocks, 855: int varno, 856: Query *parsetree) 1.71 momjian 857: { 1.112 tgl 858: List *matching_locks = NIL; 1.81 tgl 859: int nlocks; 860: int i; 1.58 tgl 861: 1.118 tgl 862: if (rulelocks == NULL) 863: return NIL; 1.22 momjian 864: 1.81 tgl 865: if (parsetree->commandType != CMD_SELECT) 1.58 tgl 866: { 1.81 tgl 867: if (parsetree->resultRelation != varno) 868: return NIL; 1.58 tgl 869: } 1.22 momjian 870: 1.81 tgl 871: nlocks = rulelocks->numLocks; 1.22 momjian 872: 1.81 tgl 873: for (i = 0; i < nlocks; i++) 1.45 momjian 874: { 1.81 tgl 875: RewriteRule *oneLock = rulelocks->rules[i]; 1.22 momjian 876: 1.81 tgl 877: if (oneLock->event == event) 1.63 tgl 878: { 1.81 tgl 879: if (parsetree->commandType != CMD_SELECT || 880: (oneLock->attrno == -1 ? 881: rangeTableEntry_used((Node *) parsetree, varno, 0) : 882: attribute_used((Node *) parsetree, 883: varno, oneLock->attrno, 0))) 1.112 tgl 884: matching_locks = lappend(matching_locks, oneLock); 1.63 tgl 885: } 1.22 momjian 886: } 1.45 momjian 887: 1.112 tgl 888: return matching_locks; 1.58 tgl 889: } 1.22 momjian 890: 891: 1.153 tgl 892: /* 893: * ApplyRetrieveRule - expand an ON SELECT rule 894: */ 1.81 tgl 895: static Query * 896: ApplyRetrieveRule(Query *parsetree, 897: RewriteRule *rule, 898: int rt_index, 899: bool relation_level, 900: Relation relation, 1.118 tgl 901: List *activeRIRs) 1.58 tgl 902: { 1.81 tgl 903: Query *rule_action; 904: RangeTblEntry *rte, 905: *subrte; 1.22 momjian 906: 1.138 neilc 907: if (list_length(rule->actions) != 1) 1.124 tgl 908: elog(ERROR, "expected just one rule action"); 1.81 tgl 909: if (rule->qual != NULL) 1.124 tgl 910: elog(ERROR, "cannot handle qualified ON SELECT rule"); 1.90 momjian 911: if (!relation_level) 1.124 tgl 912: elog(ERROR, "cannot handle per-attribute ON SELECT rule"); 1.71 momjian 913: 1.63 tgl 914: /* 1.153 tgl 915: * Make a modifiable copy of the view query, and acquire needed locks 916: * on the relations it mentions. 1.58 tgl 917: */ 1.136 neilc 918: rule_action = copyObject(linitial(rule->actions)); 1.22 momjian 919: 1.153 tgl 920: AcquireRewriteLocks(rule_action); 921: 922: /* 923: * Recursively expand any view references inside the view. 924: */ 1.118 tgl 925: rule_action = fireRIRrules(rule_action, activeRIRs); 1.22 momjian 926: 1.81 tgl 927: /* 1.90 momjian 928: * VIEWs are really easy --- just plug the view query in as a 929: * subselect, replacing the relation's original RTE. 1.81 tgl 930: */ 931: rte = rt_fetch(rt_index, parsetree->rtable); 1.58 tgl 932: 1.99 tgl 933: rte->rtekind = RTE_SUBQUERY; 1.81 tgl 934: rte->relid = InvalidOid; 935: rte->subquery = rule_action; 936: rte->inh = false; /* must not be set for a subquery */ 1.71 momjian 937: 1.58 tgl 938: /* 1.81 tgl 939: * We move the view's permission check data down to its rangetable. 940: * The checks will actually be done against the *OLD* entry therein. 1.58 tgl 941: */ 1.81 tgl 942: subrte = rt_fetch(PRS2_OLD_VARNO, rule_action->rtable); 943: Assert(subrte->relid == relation->rd_id); 1.133 tgl 944: subrte->requiredPerms = rte->requiredPerms; 1.93 tgl 945: subrte->checkAsUser = rte->checkAsUser; 1.27 thomas 946: 1.133 tgl 947: rte->requiredPerms = 0; /* no permission check on subquery itself */ 1.155 ! tgl 948: rte->checkAsUser = InvalidOid; 1.60 tgl 949: 1.71 momjian 950: /* 1.151 tgl 951: * FOR UPDATE/SHARE of view? 1.60 tgl 952: */ 1.138 neilc 953: if (list_member_int(parsetree->rowMarks, rt_index)) 1.22 momjian 954: { 1.45 momjian 955: /* 1.81 tgl 956: * Remove the view from the list of rels that will actually be 1.151 tgl 957: * marked FOR UPDATE/SHARE by the executor. It will still be access- 1.81 tgl 958: * checked for write access, though. 1.29 vadim 959: */ 1.138 neilc 960: parsetree->rowMarks = list_delete_int(parsetree->rowMarks, rt_index); 1.58 tgl 961: 1.81 tgl 962: /* 1.151 tgl 963: * Set up the view's referenced tables as if FOR UPDATE/SHARE. 1.81 tgl 964: */ 1.151 tgl 965: markQueryForLocking(rule_action, parsetree->forUpdate, true); 1.86 tgl 966: } 967: 968: return parsetree; 969: } 970: 971: /* 1.151 tgl 972: * Recursively mark all relations used by a view as FOR UPDATE/SHARE. 1.86 tgl 973: * 974: * This may generate an invalid query, eg if some sub-query uses an 975: * aggregate. We leave it to the planner to detect that. 976: * 1.151 tgl 977: * NB: this must agree with the parser's transformLocking() routine. 1.86 tgl 978: */ 979: static void 1.151 tgl 980: markQueryForLocking(Query *qry, bool forUpdate, bool skipOldNew) 1.86 tgl 981: { 982: Index rti = 0; 1.136 neilc 983: ListCell *l; 1.86 tgl 984: 1.151 tgl 985: if (qry->rowMarks && forUpdate != qry->forUpdate) 986: ereport(ERROR, 987: (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), 988: errmsg("cannot use both FOR UPDATE and FOR SHARE in one query"))); 989: qry->forUpdate = forUpdate; 990: 1.86 tgl 991: foreach(l, qry->rtable) 992: { 993: RangeTblEntry *rte = (RangeTblEntry *) lfirst(l); 994: 995: rti++; 996: 997: /* Ignore OLD and NEW entries if we are at top level of view */ 998: if (skipOldNew && 999: (rti == PRS2_OLD_VARNO || rti == PRS2_NEW_VARNO)) 1000: continue; 1001: 1.99 tgl 1002: if (rte->rtekind == RTE_RELATION) 1.86 tgl 1003: { 1.138 neilc 1004: if (!list_member_int(qry->rowMarks, rti)) 1005: qry->rowMarks = lappend_int(qry->rowMarks, rti); 1.133 tgl 1006: rte->requiredPerms |= ACL_SELECT_FOR_UPDATE; 1.29 vadim 1007: } 1.99 tgl 1008: else if (rte->rtekind == RTE_SUBQUERY) 1009: { 1.151 tgl 1010: /* FOR UPDATE/SHARE of subquery is propagated to subquery's rels */ 1011: markQueryForLocking(rte->subquery, forUpdate, false); 1.99 tgl 1012: } 1.29 vadim 1013: } 1.22 momjian 1014: } 1015: 1016: 1.58 tgl 1017: /* 1.81 tgl 1018: * fireRIRonSubLink - 1019: * Apply fireRIRrules() to each SubLink (subselect in expression) found 1020: * in the given tree. 1.58 tgl 1021: * 1022: * NOTE: although this has the form of a walker, we cheat and modify the 1.71 momjian 1023: * SubLink nodes in-place. It is caller's responsibility to ensure that 1.58 tgl 1024: * no unwanted side-effects occur! 1.80 tgl 1025: * 1026: * This is unlike most of the other routines that recurse into subselects, 1027: * because we must take control at the SubLink node in order to replace 1028: * the SubLink's subselect link with the possibly-rewritten subquery. 1.58 tgl 1029: */ 1030: static bool 1.118 tgl 1031: fireRIRonSubLink(Node *node, List *activeRIRs) 1.22 momjian 1032: { 1033: if (node == NULL) 1.58 tgl 1034: return false; 1035: if (IsA(node, SubLink)) 1036: { 1037: SubLink *sub = (SubLink *) node; 1.22 momjian 1038: 1.58 tgl 1039: /* Do what we came for */ 1.118 tgl 1040: sub->subselect = (Node *) fireRIRrules((Query *) sub->subselect, 1041: activeRIRs); 1.80 tgl 1042: /* Fall through to process lefthand args of SubLink */ 1.22 momjian 1043: } 1.90 momjian 1044: 1.80 tgl 1045: /* 1046: * Do NOT recurse into Query nodes, because fireRIRrules already 1.81 tgl 1047: * processed subselects of subselects for us. 1.80 tgl 1048: */ 1.81 tgl 1049: return expression_tree_walker(node, fireRIRonSubLink, 1.118 tgl 1050: (void *) activeRIRs); 1.22 momjian 1051: } 1052: 1053: 1054: /* 1055: * fireRIRrules - 1056: * Apply all RIR rules on each rangetable entry in a query 1057: */ 1058: static Query * 1.118 tgl 1059: fireRIRrules(Query *parsetree, List *activeRIRs) 1.22 momjian 1060: { 1.45 momjian 1061: int rt_index; 1.22 momjian 1062: 1.71 momjian 1063: /* 1064: * don't try to convert this into a foreach loop, because rtable list 1065: * can get changed each time through... 1.60 tgl 1066: */ 1.22 momjian 1067: rt_index = 0; 1.138 neilc 1068: while (rt_index < list_length(parsetree->rtable)) 1.45 momjian 1069: { 1.83 tgl 1070: RangeTblEntry *rte; 1071: Relation rel; 1072: List *locks; 1073: RuleLock *rules; 1074: RewriteRule *rule; 1075: int i; 1076: 1.22 momjian 1077: ++rt_index; 1078: 1.62 tgl 1079: rte = rt_fetch(rt_index, parsetree->rtable); 1.44 wieck 1080: 1.60 tgl 1081: /* 1.81 tgl 1082: * A subquery RTE can't have associated rules, so there's nothing 1083: * to do to this level of the query, but we must recurse into the 1084: * subquery to expand any rule references in it. 1085: */ 1.99 tgl 1086: if (rte->rtekind == RTE_SUBQUERY) 1.81 tgl 1087: { 1.118 tgl 1088: rte->subquery = fireRIRrules(rte->subquery, activeRIRs); 1.81 tgl 1089: continue; 1090: } 1091: 1092: /* 1.99 tgl 1093: * Joins and other non-relation RTEs can be ignored completely. 1094: */ 1095: if (rte->rtekind != RTE_RELATION) 1096: continue; 1097: 1098: /* 1.72 tgl 1099: * If the table is not referenced in the query, then we ignore it. 1100: * This prevents infinite expansion loop due to new rtable entries 1101: * inserted by expansion of a rule. A table is referenced if it is 1.80 tgl 1102: * part of the join set (a source table), or is referenced by any 1103: * Var nodes, or is the result table. 1.60 tgl 1104: */ 1.152 tgl 1105: if (rt_index != parsetree->resultRelation && 1106: !rangeTableEntry_used((Node *) parsetree, rt_index, 0)) 1.22 momjian 1107: continue; 1.45 momjian 1108: 1.83 tgl 1109: /* 1.153 tgl 1110: * We can use NoLock here since either the parser or 1111: * AcquireRewriteLocks should have locked the rel already. 1.83 tgl 1112: */ 1.153 tgl 1113: rel = heap_open(rte->relid, NoLock); 1.92 tgl 1114: 1115: /* 1116: * Collect the RIR rules that we must apply 1117: */ 1.60 tgl 1118: rules = rel->rd_rules; 1119: if (rules == NULL) 1.45 momjian 1120: { 1.83 tgl 1121: heap_close(rel, NoLock); 1.22 momjian 1122: continue; 1123: } 1.60 tgl 1124: locks = NIL; 1.45 momjian 1125: for (i = 0; i < rules->numLocks; i++) 1126: { 1.22 momjian 1127: rule = rules->rules[i]; 1128: if (rule->event != CMD_SELECT) 1129: continue; 1.45 momjian 1130: 1.60 tgl 1131: if (rule->attrno > 0) 1132: { 1133: /* per-attr rule; do we need it? */ 1.80 tgl 1134: if (!attribute_used((Node *) parsetree, rt_index, 1.71 momjian 1135: rule->attrno, 0)) 1.60 tgl 1136: continue; 1137: } 1.22 momjian 1138: 1139: locks = lappend(locks, rule); 1140: } 1141: 1142: /* 1.118 tgl 1143: * If we found any, apply them --- but first check for recursion! 1.22 momjian 1144: */ 1.118 tgl 1145: if (locks != NIL) 1.45 momjian 1146: { 1.136 neilc 1147: ListCell *l; 1.118 tgl 1148: 1.138 neilc 1149: if (list_member_oid(activeRIRs, RelationGetRelid(rel))) 1.124 tgl 1150: ereport(ERROR, 1151: (errcode(ERRCODE_INVALID_OBJECT_DEFINITION), 1152: errmsg("infinite recursion detected in rules for relation \"%s\"", 1153: RelationGetRelationName(rel)))); 1.138 neilc 1154: activeRIRs = lcons_oid(RelationGetRelid(rel), activeRIRs); 1.118 tgl 1155: 1156: foreach(l, locks) 1157: { 1158: rule = lfirst(l); 1.22 momjian 1159: 1.118 tgl 1160: parsetree = ApplyRetrieveRule(parsetree, 1161: rule, 1162: rt_index, 1163: rule->attrno == -1, 1164: rel, 1.137 tgl 1165: activeRIRs); 1.118 tgl 1166: } 1.137 tgl 1167: 1168: activeRIRs = list_delete_first(activeRIRs); 1.4 momjian 1169: } 1.22 momjian 1170: 1.83 tgl 1171: heap_close(rel, NoLock); 1.22 momjian 1172: } 1173: 1.81 tgl 1174: /* 1.109 tgl 1175: * Recurse into sublink subqueries, too. But we already did the ones 1176: * in the rtable. 1.81 tgl 1177: */ 1178: if (parsetree->hasSubLinks) 1.118 tgl 1179: query_tree_walker(parsetree, fireRIRonSubLink, (void *) activeRIRs, 1.116 tgl 1180: QTW_IGNORE_RT_SUBQUERIES); 1.81 tgl 1181: 1.22 momjian 1182: return parsetree; 1183: } 1184: 1185: 1186: /* 1.113 tgl 1187: * Modify the given query by adding 'AND rule_qual IS NOT TRUE' to its 1188: * qualification. This is used to generate suitable "else clauses" for 1189: * conditional INSTEAD rules. (Unfortunately we must use "x IS NOT TRUE", 1190: * not just "NOT x" which the planner is much smarter about, else we will 1191: * do the wrong thing when the qual evaluates to NULL.) 1.84 tgl 1192: * 1.90 momjian 1193: * The rule_qual may contain references to OLD or NEW. OLD references are 1.84 tgl 1194: * replaced by references to the specified rt_index (the relation that the 1195: * rule applies to). NEW references are only possible for INSERT and UPDATE 1196: * queries on the relation itself, and so they should be replaced by copies 1197: * of the related entries in the query's own targetlist. 1198: */ 1.5 momjian 1199: static Query * 1.113 tgl 1200: CopyAndAddInvertedQual(Query *parsetree, 1201: Node *rule_qual, 1202: int rt_index, 1203: CmdType event) 1.4 momjian 1204: { 1.153 tgl 1205: /* Don't scribble on the passed qual (it's in the relcache!) */ 1.84 tgl 1206: Node *new_qual = (Node *) copyObject(rule_qual); 1.4 momjian 1207: 1.153 tgl 1208: /* 1209: * In case there are subqueries in the qual, acquire necessary locks and 1210: * fix any deleted JOIN RTE entries. (This is somewhat redundant with 1211: * rewriteRuleAction, but not entirely ... consider restructuring so 1212: * that we only need to process the qual this way once.) 1213: */ 1214: (void) acquireLocksOnSubLinks(new_qual, NULL); 1215: 1.84 tgl 1216: /* Fix references to OLD */ 1217: ChangeVarNodes(new_qual, PRS2_OLD_VARNO, rt_index, 0); 1218: /* Fix references to NEW */ 1219: if (event == CMD_INSERT || event == CMD_UPDATE) 1220: new_qual = ResolveNew(new_qual, 1221: PRS2_NEW_VARNO, 1222: 0, 1.154 tgl 1223: rt_fetch(rt_index, parsetree->rtable), 1.84 tgl 1224: parsetree->targetList, 1225: event, 1226: rt_index); 1227: /* And attach the fixed qual */ 1.153 tgl 1228: AddInvertedQual(parsetree, new_qual); 1.4 momjian 1229: 1.153 tgl 1230: return parsetree; 1.1 scrappy 1231: } 1232: 1233: 1234: /* 1.4 momjian 1235: * fireRules - 1.18 scrappy 1236: * Iterate through rule locks applying rules. 1.21 momjian 1237: * 1.112 tgl 1238: * Input arguments: 1239: * parsetree - original query 1240: * rt_index - RT index of result relation in original query 1241: * event - type of rule event 1242: * locks - list of rules to fire 1243: * Output arguments: 1244: * *instead_flag - set TRUE if any unqualified INSTEAD rule is found 1245: * (must be initialized to FALSE) 1246: * *qual_product - filled with modified original query if any qualified 1247: * INSTEAD rule is found (must be initialized to NULL) 1248: * Return value: 1249: * list of rule actions adjusted for use with this query 1.1 scrappy 1250: * 1.112 tgl 1251: * Qualified INSTEAD rules generate their action with the qualification 1252: * condition added. They also generate a modified version of the original 1253: * query with the negated qualification added, so that it will run only for 1254: * rows that the qualified action doesn't act on. (If there are multiple 1255: * qualified INSTEAD rules, we AND all the negated quals onto a single 1256: * modified original query.) We won't execute the original, unmodified 1.126 momjian 1257: * query if we find either qualified or unqualified INSTEAD rules. If 1.112 tgl 1258: * we find both, the modified original query is discarded too. 1.1 scrappy 1259: */ 1.5 momjian 1260: static List * 1.6 momjian 1261: fireRules(Query *parsetree, 1.4 momjian 1262: int rt_index, 1263: CmdType event, 1.112 tgl 1264: List *locks, 1.6 momjian 1265: bool *instead_flag, 1.112 tgl 1266: Query **qual_product) 1.4 momjian 1267: { 1.5 momjian 1268: List *results = NIL; 1.136 neilc 1269: ListCell *l; 1.4 momjian 1270: 1.136 neilc 1271: foreach(l, locks) 1.4 momjian 1272: { 1.136 neilc 1273: RewriteRule *rule_lock = (RewriteRule *) lfirst(l); 1.112 tgl 1274: Node *event_qual = rule_lock->qual; 1275: List *actions = rule_lock->actions; 1.126 momjian 1276: QuerySource qsrc; 1.136 neilc 1277: ListCell *r; 1.4 momjian 1278: 1.111 tgl 1279: /* Determine correct QuerySource value for actions */ 1280: if (rule_lock->isInstead) 1281: { 1282: if (event_qual != NULL) 1283: qsrc = QSRC_QUAL_INSTEAD_RULE; 1284: else 1.112 tgl 1285: { 1.111 tgl 1286: qsrc = QSRC_INSTEAD_RULE; 1.126 momjian 1287: *instead_flag = true; /* report unqualified INSTEAD */ 1.112 tgl 1288: } 1.111 tgl 1289: } 1290: else 1291: qsrc = QSRC_NON_INSTEAD_RULE; 1292: 1293: if (qsrc == QSRC_QUAL_INSTEAD_RULE) 1.21 momjian 1294: { 1.91 momjian 1295: /* 1.112 tgl 1296: * If there are INSTEAD rules with qualifications, the 1.91 momjian 1297: * original query is still performed. But all the negated rule 1.112 tgl 1298: * qualifications of the INSTEAD rules are added so it does 1.91 momjian 1299: * its actions only in cases where the rule quals of all 1.112 tgl 1300: * INSTEAD rules are false. Think of it as the default action 1.126 momjian 1301: * in a case. We save this in *qual_product so RewriteQuery() 1302: * can add it to the query list after we mangled it up enough. 1.112 tgl 1303: * 1.126 momjian 1304: * If we have already found an unqualified INSTEAD rule, then 1305: * *qual_product won't be used, so don't bother building it. 1.18 scrappy 1306: */ 1.126 momjian 1307: if (!*instead_flag) 1.112 tgl 1308: { 1309: if (*qual_product == NULL) 1.153 tgl 1310: *qual_product = copyObject(parsetree); 1.113 tgl 1311: *qual_product = CopyAndAddInvertedQual(*qual_product, 1312: event_qual, 1313: rt_index, 1314: event); 1.112 tgl 1315: } 1.18 scrappy 1316: } 1317: 1.111 tgl 1318: /* Now process the rule's actions and add them to the result list */ 1.4 momjian 1319: foreach(r, actions) 1320: { 1.5 momjian 1321: Query *rule_action = lfirst(r); 1.4 momjian 1322: 1.18 scrappy 1323: if (rule_action->commandType == CMD_NOTHING) 1324: continue; 1.25 momjian 1325: 1.95 tgl 1326: rule_action = rewriteRuleAction(parsetree, rule_action, 1327: event_qual, rt_index, event); 1.4 momjian 1328: 1.111 tgl 1329: rule_action->querySource = qsrc; 1.120 tgl 1330: rule_action->canSetTag = false; /* might change later */ 1.111 tgl 1331: 1.95 tgl 1332: results = lappend(results, rule_action); 1.4 momjian 1333: } 1334: } 1.111 tgl 1335: 1.4 momjian 1336: return results; 1337: } 1338: 1.18 scrappy 1339: 1.112 tgl 1340: /* 1.118 tgl 1341: * RewriteQuery - 1342: * rewrites the query and apply the rules again on the queries rewritten 1.112 tgl 1343: * 1.118 tgl 1344: * rewrite_events is a list of open query-rewrite actions, so we can detect 1345: * infinite recursion. 1.112 tgl 1346: */ 1.5 momjian 1347: static List * 1.118 tgl 1348: RewriteQuery(Query *parsetree, List *rewrite_events) 1.4 momjian 1349: { 1.118 tgl 1350: CmdType event = parsetree->commandType; 1351: bool instead = false; 1352: Query *qual_product = NULL; 1353: List *rewritten = NIL; 1.1 scrappy 1354: 1.22 momjian 1355: /* 1.118 tgl 1356: * If the statement is an update, insert or delete - fire rules on it. 1357: * 1.45 momjian 1358: * SELECT rules are handled later when we have all the queries that 1.126 momjian 1359: * should get executed. Also, utilities aren't rewritten at all (do 1360: * we still need that check?) 1.22 momjian 1361: */ 1.118 tgl 1362: if (event != CMD_SELECT && event != CMD_UTILITY) 1.22 momjian 1363: { 1.118 tgl 1364: int result_relation; 1365: RangeTblEntry *rt_entry; 1366: Relation rt_entry_relation; 1367: List *locks; 1.22 momjian 1368: 1.118 tgl 1369: result_relation = parsetree->resultRelation; 1370: Assert(result_relation != 0); 1371: rt_entry = rt_fetch(result_relation, parsetree->rtable); 1372: Assert(rt_entry->rtekind == RTE_RELATION); 1.1 scrappy 1373: 1.118 tgl 1374: /* 1.153 tgl 1375: * We can use NoLock here since either the parser or 1376: * AcquireRewriteLocks should have locked the rel already. 1.118 tgl 1377: */ 1.153 tgl 1378: rt_entry_relation = heap_open(rt_entry->relid, NoLock); 1.77 tgl 1379: 1.118 tgl 1380: /* 1.126 momjian 1381: * If it's an INSERT or UPDATE, rewrite the targetlist into 1382: * standard form. This will be needed by the planner anyway, and 1383: * doing it now ensures that any references to NEW.field will 1384: * behave sanely. 1.118 tgl 1385: */ 1386: if (event == CMD_INSERT || event == CMD_UPDATE) 1387: rewriteTargetList(parsetree, rt_entry_relation); 1.10 momjian 1388: 1.118 tgl 1389: /* 1390: * Collect and apply the appropriate rules. 1391: */ 1392: locks = matchLocks(event, rt_entry_relation->rd_rules, 1393: result_relation, parsetree); 1.1 scrappy 1394: 1.118 tgl 1395: if (locks != NIL) 1396: { 1397: List *product_queries; 1.1 scrappy 1398: 1.118 tgl 1399: product_queries = fireRules(parsetree, 1400: result_relation, 1401: event, 1402: locks, 1403: &instead, 1404: &qual_product); 1.1 scrappy 1405: 1.118 tgl 1406: /* 1.126 momjian 1407: * If we got any product queries, recursively rewrite them --- 1408: * but first check for recursion! 1.118 tgl 1409: */ 1410: if (product_queries != NIL) 1411: { 1.144 momjian 1412: ListCell *n; 1413: rewrite_event *rev; 1.4 momjian 1414: 1.118 tgl 1415: foreach(n, rewrite_events) 1416: { 1417: rev = (rewrite_event *) lfirst(n); 1418: if (rev->relation == RelationGetRelid(rt_entry_relation) && 1419: rev->event == event) 1.124 tgl 1420: ereport(ERROR, 1.126 momjian 1421: (errcode(ERRCODE_INVALID_OBJECT_DEFINITION), 1422: errmsg("infinite recursion detected in rules for relation \"%s\"", 1423: RelationGetRelationName(rt_entry_relation)))); 1.118 tgl 1424: } 1425: 1426: rev = (rewrite_event *) palloc(sizeof(rewrite_event)); 1427: rev->relation = RelationGetRelid(rt_entry_relation); 1428: rev->event = event; 1429: rewrite_events = lcons(rev, rewrite_events); 1430: 1431: foreach(n, product_queries) 1432: { 1433: Query *pt = (Query *) lfirst(n); 1434: List *newstuff; 1435: 1436: newstuff = RewriteQuery(pt, rewrite_events); 1.138 neilc 1437: rewritten = list_concat(rewritten, newstuff); 1.118 tgl 1438: } 1.146 tgl 1439: 1440: rewrite_events = list_delete_first(rewrite_events); 1.118 tgl 1441: } 1442: } 1.4 momjian 1443: 1.153 tgl 1444: heap_close(rt_entry_relation, NoLock); 1.4 momjian 1445: } 1.18 scrappy 1446: 1.91 momjian 1447: /* 1.98 momjian 1448: * For INSERTs, the original query is done first; for UPDATE/DELETE, 1449: * it is done last. This is needed because update and delete rule 1450: * actions might not do anything if they are invoked after the update 1451: * or delete is performed. The command counter increment between the 1.112 tgl 1452: * query executions makes the deleted (and maybe the updated) tuples 1.98 momjian 1453: * disappear so the scans for them in the rule actions cannot find 1454: * them. 1.112 tgl 1455: * 1.126 momjian 1456: * If we found any unqualified INSTEAD, the original query is not done at 1457: * all, in any form. Otherwise, we add the modified form if qualified 1458: * INSTEADs were found, else the unmodified form. 1.18 scrappy 1459: */ 1.112 tgl 1460: if (!instead) 1.97 tgl 1461: { 1.112 tgl 1462: if (parsetree->commandType == CMD_INSERT) 1463: { 1464: if (qual_product != NULL) 1465: rewritten = lcons(qual_product, rewritten); 1466: else 1467: rewritten = lcons(parsetree, rewritten); 1468: } 1469: else 1470: { 1471: if (qual_product != NULL) 1472: rewritten = lappend(rewritten, qual_product); 1473: else 1474: rewritten = lappend(rewritten, parsetree); 1475: } 1.97 tgl 1476: } 1.4 momjian 1477: 1478: return rewritten; 1.12 scrappy 1479: } 1.22 momjian 1480: 1481: 1482: /* 1.82 tgl 1483: * QueryRewrite - 1484: * Primary entry point to the query rewriter. 1485: * Rewrite one query via query rewrite system, possibly returning 0 1486: * or many queries. 1487: * 1.153 tgl 1488: * NOTE: the parsetree must either have come straight from the parser, 1489: * or have been scanned by AcquireRewriteLocks to acquire suitable locks. 1.22 momjian 1490: */ 1.82 tgl 1491: List * 1492: QueryRewrite(Query *parsetree) 1.22 momjian 1493: { 1.45 momjian 1494: List *querylist; 1495: List *results = NIL; 1.136 neilc 1496: ListCell *l; 1.120 tgl 1497: CmdType origCmdType; 1498: bool foundOriginalQuery; 1499: Query *lastInstead; 1.22 momjian 1500: 1501: /* 1502: * Step 1 1503: * 1504: * Apply all non-SELECT rules possibly getting 0 or many queries 1505: */ 1.118 tgl 1506: querylist = RewriteQuery(parsetree, NIL); 1.22 momjian 1507: 1508: /* 1.62 tgl 1509: * Step 2 1.22 momjian 1510: * 1511: * Apply all the RIR rules on each query 1512: */ 1.45 momjian 1513: foreach(l, querylist) 1514: { 1.90 momjian 1515: Query *query = (Query *) lfirst(l); 1.45 momjian 1516: 1.118 tgl 1517: query = fireRIRrules(query, NIL); 1.71 momjian 1518: 1.45 momjian 1519: /* 1.82 tgl 1520: * If the query target was rewritten as a view, complain. 1.45 momjian 1521: */ 1.82 tgl 1522: if (query->resultRelation) 1.45 momjian 1523: { 1.82 tgl 1524: RangeTblEntry *rte = rt_fetch(query->resultRelation, 1525: query->rtable); 1526: 1.99 tgl 1527: if (rte->rtekind == RTE_SUBQUERY) 1.82 tgl 1528: { 1529: switch (query->commandType) 1530: { 1531: case CMD_INSERT: 1.124 tgl 1532: ereport(ERROR, 1533: (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), 1534: errmsg("cannot insert into a view"), 1535: errhint("You need an unconditional ON INSERT DO INSTEAD rule."))); 1.82 tgl 1536: break; 1537: case CMD_UPDATE: 1.124 tgl 1538: ereport(ERROR, 1539: (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), 1540: errmsg("cannot update a view"), 1541: errhint("You need an unconditional ON UPDATE DO INSTEAD rule."))); 1.82 tgl 1542: break; 1543: case CMD_DELETE: 1.124 tgl 1544: ereport(ERROR, 1545: (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), 1546: errmsg("cannot delete from a view"), 1547: errhint("You need an unconditional ON DELETE DO INSTEAD rule."))); 1.82 tgl 1548: break; 1549: default: 1.124 tgl 1550: elog(ERROR, "unrecognized commandType: %d", 1.82 tgl 1551: (int) query->commandType); 1552: break; 1553: } 1.45 momjian 1554: } 1555: } 1556: 1.82 tgl 1557: results = lappend(results, query); 1.45 momjian 1558: } 1.120 tgl 1559: 1560: /* 1561: * Step 3 1562: * 1563: * Determine which, if any, of the resulting queries is supposed to set 1.126 momjian 1564: * the command-result tag; and update the canSetTag fields 1565: * accordingly. 1.120 tgl 1566: * 1567: * If the original query is still in the list, it sets the command tag. 1568: * Otherwise, the last INSTEAD query of the same kind as the original 1569: * is allowed to set the tag. (Note these rules can leave us with no 1570: * query setting the tag. The tcop code has to cope with this by 1571: * setting up a default tag based on the original un-rewritten query.) 1572: * 1573: * The Asserts verify that at most one query in the result list is marked 1.126 momjian 1574: * canSetTag. If we aren't checking asserts, we can fall out of the 1575: * loop as soon as we find the original query. 1.120 tgl 1576: */ 1577: origCmdType = parsetree->commandType; 1578: foundOriginalQuery = false; 1579: lastInstead = NULL; 1580: 1581: foreach(l, results) 1582: { 1583: Query *query = (Query *) lfirst(l); 1584: 1585: if (query->querySource == QSRC_ORIGINAL) 1586: { 1587: Assert(query->canSetTag); 1588: Assert(!foundOriginalQuery); 1589: foundOriginalQuery = true; 1590: #ifndef USE_ASSERT_CHECKING 1591: break; 1592: #endif 1593: } 1594: else 1595: { 1596: Assert(!query->canSetTag); 1597: if (query->commandType == origCmdType && 1598: (query->querySource == QSRC_INSTEAD_RULE || 1599: query->querySource == QSRC_QUAL_INSTEAD_RULE)) 1600: lastInstead = query; 1601: } 1602: } 1603: 1604: if (!foundOriginalQuery && lastInstead != NULL) 1605: lastInstead->canSetTag = true; 1.45 momjian 1606: 1.82 tgl 1607: return results; 1.22 momjian 1608: }
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