LCOV - code coverage report
Current view: top level - src/backend/commands - view.c (source / functions) Hit Total Coverage
Test: PostgreSQL 16beta1 Lines: 126 136 92.6 %
Date: 2023-05-30 16:15:03 Functions: 5 5 100.0 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * view.c
       4             :  *    use rewrite rules to construct views
       5             :  *
       6             :  * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
       7             :  * Portions Copyright (c) 1994, Regents of the University of California
       8             :  *
       9             :  *
      10             :  * IDENTIFICATION
      11             :  *    src/backend/commands/view.c
      12             :  *
      13             :  *-------------------------------------------------------------------------
      14             :  */
      15             : #include "postgres.h"
      16             : 
      17             : #include "access/relation.h"
      18             : #include "access/xact.h"
      19             : #include "catalog/namespace.h"
      20             : #include "commands/defrem.h"
      21             : #include "commands/tablecmds.h"
      22             : #include "commands/view.h"
      23             : #include "miscadmin.h"
      24             : #include "nodes/makefuncs.h"
      25             : #include "nodes/nodeFuncs.h"
      26             : #include "parser/analyze.h"
      27             : #include "parser/parse_relation.h"
      28             : #include "rewrite/rewriteDefine.h"
      29             : #include "rewrite/rewriteHandler.h"
      30             : #include "rewrite/rewriteManip.h"
      31             : #include "rewrite/rewriteSupport.h"
      32             : #include "utils/acl.h"
      33             : #include "utils/builtins.h"
      34             : #include "utils/lsyscache.h"
      35             : #include "utils/rel.h"
      36             : #include "utils/syscache.h"
      37             : 
      38             : static void checkViewTupleDesc(TupleDesc newdesc, TupleDesc olddesc);
      39             : 
      40             : /*---------------------------------------------------------------------
      41             :  * DefineVirtualRelation
      42             :  *
      43             :  * Create a view relation and use the rules system to store the query
      44             :  * for the view.
      45             :  *
      46             :  * EventTriggerAlterTableStart must have been called already.
      47             :  *---------------------------------------------------------------------
      48             :  */
      49             : static ObjectAddress
      50       87534 : DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
      51             :                       List *options, Query *viewParse)
      52             : {
      53             :     Oid         viewOid;
      54             :     LOCKMODE    lockmode;
      55       87534 :     CreateStmt *createStmt = makeNode(CreateStmt);
      56             :     List       *attrList;
      57             :     ListCell   *t;
      58             : 
      59             :     /*
      60             :      * create a list of ColumnDef nodes based on the names and types of the
      61             :      * (non-junk) targetlist items from the view's SELECT list.
      62             :      */
      63       87534 :     attrList = NIL;
      64      965134 :     foreach(t, tlist)
      65             :     {
      66      877600 :         TargetEntry *tle = (TargetEntry *) lfirst(t);
      67             : 
      68      877600 :         if (!tle->resjunk)
      69             :         {
      70      873926 :             ColumnDef  *def = makeColumnDef(tle->resname,
      71      873926 :                                             exprType((Node *) tle->expr),
      72      873926 :                                             exprTypmod((Node *) tle->expr),
      73      873926 :                                             exprCollation((Node *) tle->expr));
      74             : 
      75             :             /*
      76             :              * It's possible that the column is of a collatable type but the
      77             :              * collation could not be resolved, so double-check.
      78             :              */
      79      873926 :             if (type_is_collatable(exprType((Node *) tle->expr)))
      80             :             {
      81      502204 :                 if (!OidIsValid(def->collOid))
      82           0 :                     ereport(ERROR,
      83             :                             (errcode(ERRCODE_INDETERMINATE_COLLATION),
      84             :                              errmsg("could not determine which collation to use for view column \"%s\"",
      85             :                                     def->colname),
      86             :                              errhint("Use the COLLATE clause to set the collation explicitly.")));
      87             :             }
      88             :             else
      89             :                 Assert(!OidIsValid(def->collOid));
      90             : 
      91      873926 :             attrList = lappend(attrList, def);
      92             :         }
      93             :     }
      94             : 
      95             :     /*
      96             :      * Look up, check permissions on, and lock the creation namespace; also
      97             :      * check for a preexisting view with the same name.  This will also set
      98             :      * relation->relpersistence to RELPERSISTENCE_TEMP if the selected
      99             :      * namespace is temporary.
     100             :      */
     101       87534 :     lockmode = replace ? AccessExclusiveLock : NoLock;
     102       87534 :     (void) RangeVarGetAndCheckCreationNamespace(relation, lockmode, &viewOid);
     103             : 
     104       87522 :     if (OidIsValid(viewOid) && replace)
     105             :     {
     106             :         Relation    rel;
     107             :         TupleDesc   descriptor;
     108         224 :         List       *atcmds = NIL;
     109             :         AlterTableCmd *atcmd;
     110             :         ObjectAddress address;
     111             : 
     112             :         /* Relation is already locked, but we must build a relcache entry. */
     113         224 :         rel = relation_open(viewOid, NoLock);
     114             : 
     115             :         /* Make sure it *is* a view. */
     116         224 :         if (rel->rd_rel->relkind != RELKIND_VIEW)
     117           0 :             ereport(ERROR,
     118             :                     (errcode(ERRCODE_WRONG_OBJECT_TYPE),
     119             :                      errmsg("\"%s\" is not a view",
     120             :                             RelationGetRelationName(rel))));
     121             : 
     122             :         /* Also check it's not in use already */
     123         224 :         CheckTableNotInUse(rel, "CREATE OR REPLACE VIEW");
     124             : 
     125             :         /*
     126             :          * Due to the namespace visibility rules for temporary objects, we
     127             :          * should only end up replacing a temporary view with another
     128             :          * temporary view, and similarly for permanent views.
     129             :          */
     130             :         Assert(relation->relpersistence == rel->rd_rel->relpersistence);
     131             : 
     132             :         /*
     133             :          * Create a tuple descriptor to compare against the existing view, and
     134             :          * verify that the old column list is an initial prefix of the new
     135             :          * column list.
     136             :          */
     137         224 :         descriptor = BuildDescForRelation(attrList);
     138         224 :         checkViewTupleDesc(descriptor, rel->rd_att);
     139             : 
     140             :         /*
     141             :          * If new attributes have been added, we must add pg_attribute entries
     142             :          * for them.  It is convenient (although overkill) to use the ALTER
     143             :          * TABLE ADD COLUMN infrastructure for this.
     144             :          *
     145             :          * Note that we must do this before updating the query for the view,
     146             :          * since the rules system requires that the correct view columns be in
     147             :          * place when defining the new rules.
     148             :          *
     149             :          * Also note that ALTER TABLE doesn't run parse transformation on
     150             :          * AT_AddColumnToView commands.  The ColumnDef we supply must be ready
     151             :          * to execute as-is.
     152             :          */
     153         194 :         if (list_length(attrList) > rel->rd_att->natts)
     154             :         {
     155             :             ListCell   *c;
     156          24 :             int         skip = rel->rd_att->natts;
     157             : 
     158          96 :             foreach(c, attrList)
     159             :             {
     160          72 :                 if (skip > 0)
     161             :                 {
     162          48 :                     skip--;
     163          48 :                     continue;
     164             :                 }
     165          24 :                 atcmd = makeNode(AlterTableCmd);
     166          24 :                 atcmd->subtype = AT_AddColumnToView;
     167          24 :                 atcmd->def = (Node *) lfirst(c);
     168          24 :                 atcmds = lappend(atcmds, atcmd);
     169             :             }
     170             : 
     171             :             /* EventTriggerAlterTableStart called by ProcessUtilitySlow */
     172          24 :             AlterTableInternal(viewOid, atcmds, true);
     173             : 
     174             :             /* Make the new view columns visible */
     175          24 :             CommandCounterIncrement();
     176             :         }
     177             : 
     178             :         /*
     179             :          * Update the query for the view.
     180             :          *
     181             :          * Note that we must do this before updating the view options, because
     182             :          * the new options may not be compatible with the old view query (for
     183             :          * example if we attempt to add the WITH CHECK OPTION, we require that
     184             :          * the new view be automatically updatable, but the old view may not
     185             :          * have been).
     186             :          */
     187         194 :         StoreViewQuery(viewOid, viewParse, replace);
     188             : 
     189             :         /* Make the new view query visible */
     190         194 :         CommandCounterIncrement();
     191             : 
     192             :         /*
     193             :          * Update the view's options.
     194             :          *
     195             :          * The new options list replaces the existing options list, even if
     196             :          * it's empty.
     197             :          */
     198         194 :         atcmd = makeNode(AlterTableCmd);
     199         194 :         atcmd->subtype = AT_ReplaceRelOptions;
     200         194 :         atcmd->def = (Node *) options;
     201         194 :         atcmds = list_make1(atcmd);
     202             : 
     203             :         /* EventTriggerAlterTableStart called by ProcessUtilitySlow */
     204         194 :         AlterTableInternal(viewOid, atcmds, true);
     205             : 
     206             :         /*
     207             :          * There is very little to do here to update the view's dependencies.
     208             :          * Most view-level dependency relationships, such as those on the
     209             :          * owner, schema, and associated composite type, aren't changing.
     210             :          * Because we don't allow changing type or collation of an existing
     211             :          * view column, those dependencies of the existing columns don't
     212             :          * change either, while the AT_AddColumnToView machinery took care of
     213             :          * adding such dependencies for new view columns.  The dependencies of
     214             :          * the view's query could have changed arbitrarily, but that was dealt
     215             :          * with inside StoreViewQuery.  What remains is only to check that
     216             :          * view replacement is allowed when we're creating an extension.
     217             :          */
     218         194 :         ObjectAddressSet(address, RelationRelationId, viewOid);
     219             : 
     220         194 :         recordDependencyOnCurrentExtension(&address, true);
     221             : 
     222             :         /*
     223             :          * Seems okay, so return the OID of the pre-existing view.
     224             :          */
     225         192 :         relation_close(rel, NoLock);    /* keep the lock! */
     226             : 
     227         192 :         return address;
     228             :     }
     229             :     else
     230             :     {
     231             :         ObjectAddress address;
     232             : 
     233             :         /*
     234             :          * Set the parameters for keys/inheritance etc. All of these are
     235             :          * uninteresting for views...
     236             :          */
     237       87298 :         createStmt->relation = relation;
     238       87298 :         createStmt->tableElts = attrList;
     239       87298 :         createStmt->inhRelations = NIL;
     240       87298 :         createStmt->constraints = NIL;
     241       87298 :         createStmt->options = options;
     242       87298 :         createStmt->oncommit = ONCOMMIT_NOOP;
     243       87298 :         createStmt->tablespacename = NULL;
     244       87298 :         createStmt->if_not_exists = false;
     245             : 
     246             :         /*
     247             :          * Create the relation (this will error out if there's an existing
     248             :          * view, so we don't need more code to complain if "replace" is
     249             :          * false).
     250             :          */
     251       87298 :         address = DefineRelation(createStmt, RELKIND_VIEW, InvalidOid, NULL,
     252             :                                  NULL);
     253             :         Assert(address.objectId != InvalidOid);
     254             : 
     255             :         /* Make the new view relation visible */
     256       87280 :         CommandCounterIncrement();
     257             : 
     258             :         /* Store the query for the view */
     259       87280 :         StoreViewQuery(address.objectId, viewParse, replace);
     260             : 
     261       87280 :         return address;
     262             :     }
     263             : }
     264             : 
     265             : /*
     266             :  * Verify that tupledesc associated with proposed new view definition
     267             :  * matches tupledesc of old view.  This is basically a cut-down version
     268             :  * of equalTupleDescs(), with code added to generate specific complaints.
     269             :  * Also, we allow the new tupledesc to have more columns than the old.
     270             :  */
     271             : static void
     272         224 : checkViewTupleDesc(TupleDesc newdesc, TupleDesc olddesc)
     273             : {
     274             :     int         i;
     275             : 
     276         224 :     if (newdesc->natts < olddesc->natts)
     277           6 :         ereport(ERROR,
     278             :                 (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
     279             :                  errmsg("cannot drop columns from view")));
     280             : 
     281         598 :     for (i = 0; i < olddesc->natts; i++)
     282             :     {
     283         404 :         Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
     284         404 :         Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
     285             : 
     286             :         /* XXX msg not right, but we don't support DROP COL on view anyway */
     287         404 :         if (newattr->attisdropped != oldattr->attisdropped)
     288           0 :             ereport(ERROR,
     289             :                     (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
     290             :                      errmsg("cannot drop columns from view")));
     291             : 
     292         404 :         if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
     293           6 :             ereport(ERROR,
     294             :                     (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
     295             :                      errmsg("cannot change name of view column \"%s\" to \"%s\"",
     296             :                             NameStr(oldattr->attname),
     297             :                             NameStr(newattr->attname)),
     298             :                      errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
     299             : 
     300             :         /*
     301             :          * We cannot allow type, typmod, or collation to change, since these
     302             :          * properties may be embedded in Vars of other views/rules referencing
     303             :          * this one.  Other column attributes can be ignored.
     304             :          */
     305         398 :         if (newattr->atttypid != oldattr->atttypid ||
     306         392 :             newattr->atttypmod != oldattr->atttypmod)
     307          12 :             ereport(ERROR,
     308             :                     (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
     309             :                      errmsg("cannot change data type of view column \"%s\" from %s to %s",
     310             :                             NameStr(oldattr->attname),
     311             :                             format_type_with_typemod(oldattr->atttypid,
     312             :                                                      oldattr->atttypmod),
     313             :                             format_type_with_typemod(newattr->atttypid,
     314             :                                                      newattr->atttypmod))));
     315             : 
     316             :         /*
     317             :          * At this point, attcollations should be both valid or both invalid,
     318             :          * so applying get_collation_name unconditionally should be fine.
     319             :          */
     320         386 :         if (newattr->attcollation != oldattr->attcollation)
     321           6 :             ereport(ERROR,
     322             :                     (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
     323             :                      errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
     324             :                             NameStr(oldattr->attname),
     325             :                             get_collation_name(oldattr->attcollation),
     326             :                             get_collation_name(newattr->attcollation))));
     327             :     }
     328             : 
     329             :     /*
     330             :      * We ignore the constraint fields.  The new view desc can't have any
     331             :      * constraints, and the only ones that could be on the old view are
     332             :      * defaults, which we are happy to leave in place.
     333             :      */
     334         194 : }
     335             : 
     336             : static void
     337       87898 : DefineViewRules(Oid viewOid, Query *viewParse, bool replace)
     338             : {
     339             :     /*
     340             :      * Set up the ON SELECT rule.  Since the query has already been through
     341             :      * parse analysis, we use DefineQueryRewrite() directly.
     342             :      */
     343       87898 :     DefineQueryRewrite(pstrdup(ViewSelectRuleName),
     344             :                        viewOid,
     345             :                        NULL,
     346             :                        CMD_SELECT,
     347             :                        true,
     348             :                        replace,
     349       87898 :                        list_make1(viewParse));
     350             : 
     351             :     /*
     352             :      * Someday: automatic ON INSERT, etc
     353             :      */
     354       87898 : }
     355             : 
     356             : /*
     357             :  * DefineView
     358             :  *      Execute a CREATE VIEW command.
     359             :  */
     360             : ObjectAddress
     361       87558 : DefineView(ViewStmt *stmt, const char *queryString,
     362             :            int stmt_location, int stmt_len)
     363             : {
     364             :     RawStmt    *rawstmt;
     365             :     Query      *viewParse;
     366             :     RangeVar   *view;
     367             :     ListCell   *cell;
     368             :     bool        check_option;
     369             :     ObjectAddress address;
     370             : 
     371             :     /*
     372             :      * Run parse analysis to convert the raw parse tree to a Query.  Note this
     373             :      * also acquires sufficient locks on the source table(s).
     374             :      */
     375       87558 :     rawstmt = makeNode(RawStmt);
     376       87558 :     rawstmt->stmt = stmt->query;
     377       87558 :     rawstmt->stmt_location = stmt_location;
     378       87558 :     rawstmt->stmt_len = stmt_len;
     379             : 
     380       87558 :     viewParse = parse_analyze_fixedparams(rawstmt, queryString, NULL, 0, NULL);
     381             : 
     382             :     /*
     383             :      * The grammar should ensure that the result is a single SELECT Query.
     384             :      * However, it doesn't forbid SELECT INTO, so we have to check for that.
     385             :      */
     386       87540 :     if (!IsA(viewParse, Query))
     387           0 :         elog(ERROR, "unexpected parse analysis result");
     388       87540 :     if (viewParse->utilityStmt != NULL &&
     389           6 :         IsA(viewParse->utilityStmt, CreateTableAsStmt))
     390           6 :         ereport(ERROR,
     391             :                 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
     392             :                  errmsg("views must not contain SELECT INTO")));
     393       87534 :     if (viewParse->commandType != CMD_SELECT)
     394           0 :         elog(ERROR, "unexpected parse analysis result");
     395             : 
     396             :     /*
     397             :      * Check for unsupported cases.  These tests are redundant with ones in
     398             :      * DefineQueryRewrite(), but that function will complain about a bogus ON
     399             :      * SELECT rule, and we'd rather the message complain about a view.
     400             :      */
     401       87534 :     if (viewParse->hasModifyingCTE)
     402           0 :         ereport(ERROR,
     403             :                 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
     404             :                  errmsg("views must not contain data-modifying statements in WITH")));
     405             : 
     406             :     /*
     407             :      * If the user specified the WITH CHECK OPTION, add it to the list of
     408             :      * reloptions.
     409             :      */
     410       87534 :     if (stmt->withCheckOption == LOCAL_CHECK_OPTION)
     411          24 :         stmt->options = lappend(stmt->options,
     412          24 :                                 makeDefElem("check_option",
     413          24 :                                             (Node *) makeString("local"), -1));
     414       87510 :     else if (stmt->withCheckOption == CASCADED_CHECK_OPTION)
     415          96 :         stmt->options = lappend(stmt->options,
     416          96 :                                 makeDefElem("check_option",
     417          96 :                                             (Node *) makeString("cascaded"), -1));
     418             : 
     419             :     /*
     420             :      * Check that the view is auto-updatable if WITH CHECK OPTION was
     421             :      * specified.
     422             :      */
     423       87534 :     check_option = false;
     424             : 
     425       89688 :     foreach(cell, stmt->options)
     426             :     {
     427        2154 :         DefElem    *defel = (DefElem *) lfirst(cell);
     428             : 
     429        2154 :         if (strcmp(defel->defname, "check_option") == 0)
     430         122 :             check_option = true;
     431             :     }
     432             : 
     433             :     /*
     434             :      * If the check option is specified, look to see if the view is actually
     435             :      * auto-updatable or not.
     436             :      */
     437       87534 :     if (check_option)
     438             :     {
     439             :         const char *view_updatable_error =
     440         122 :             view_query_is_auto_updatable(viewParse, true);
     441             : 
     442         122 :         if (view_updatable_error)
     443           0 :             ereport(ERROR,
     444             :                     (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
     445             :                      errmsg("WITH CHECK OPTION is supported only on automatically updatable views"),
     446             :                      errhint("%s", _(view_updatable_error))));
     447             :     }
     448             : 
     449             :     /*
     450             :      * If a list of column names was given, run through and insert these into
     451             :      * the actual query tree. - thomas 2000-03-08
     452             :      */
     453       87534 :     if (stmt->aliases != NIL)
     454             :     {
     455          56 :         ListCell   *alist_item = list_head(stmt->aliases);
     456             :         ListCell   *targetList;
     457             : 
     458          80 :         foreach(targetList, viewParse->targetList)
     459             :         {
     460          80 :             TargetEntry *te = lfirst_node(TargetEntry, targetList);
     461             : 
     462             :             /* junk columns don't get aliases */
     463          80 :             if (te->resjunk)
     464           0 :                 continue;
     465          80 :             te->resname = pstrdup(strVal(lfirst(alist_item)));
     466          80 :             alist_item = lnext(stmt->aliases, alist_item);
     467          80 :             if (alist_item == NULL)
     468          56 :                 break;          /* done assigning aliases */
     469             :         }
     470             : 
     471          56 :         if (alist_item != NULL)
     472           0 :             ereport(ERROR,
     473             :                     (errcode(ERRCODE_SYNTAX_ERROR),
     474             :                      errmsg("CREATE VIEW specifies more column "
     475             :                             "names than columns")));
     476             :     }
     477             : 
     478             :     /* Unlogged views are not sensible. */
     479       87534 :     if (stmt->view->relpersistence == RELPERSISTENCE_UNLOGGED)
     480           0 :         ereport(ERROR,
     481             :                 (errcode(ERRCODE_SYNTAX_ERROR),
     482             :                  errmsg("views cannot be unlogged because they do not have storage")));
     483             : 
     484             :     /*
     485             :      * If the user didn't explicitly ask for a temporary view, check whether
     486             :      * we need one implicitly.  We allow TEMP to be inserted automatically as
     487             :      * long as the CREATE command is consistent with that --- no explicit
     488             :      * schema name.
     489             :      */
     490       87534 :     view = copyObject(stmt->view);   /* don't corrupt original command */
     491       87534 :     if (view->relpersistence == RELPERSISTENCE_PERMANENT
     492       87282 :         && isQueryUsingTempRelation(viewParse))
     493             :     {
     494         108 :         view->relpersistence = RELPERSISTENCE_TEMP;
     495         108 :         ereport(NOTICE,
     496             :                 (errmsg("view \"%s\" will be a temporary view",
     497             :                         view->relname)));
     498             :     }
     499             : 
     500             :     /*
     501             :      * Create the view relation
     502             :      *
     503             :      * NOTE: if it already exists and replace is false, the xact will be
     504             :      * aborted.
     505             :      */
     506       87534 :     address = DefineVirtualRelation(view, viewParse->targetList,
     507       87534 :                                     stmt->replace, stmt->options, viewParse);
     508             : 
     509       87472 :     return address;
     510             : }
     511             : 
     512             : /*
     513             :  * Use the rules system to store the query for the view.
     514             :  */
     515             : void
     516       87898 : StoreViewQuery(Oid viewOid, Query *viewParse, bool replace)
     517             : {
     518             :     /*
     519             :      * Now create the rules associated with the view.
     520             :      */
     521       87898 :     DefineViewRules(viewOid, viewParse, replace);
     522       87898 : }

Generated by: LCOV version 1.14