LCOV - code coverage report
Current view: top level - src/backend/commands - view.c (source / functions) Hit Total Coverage
Test: PostgreSQL 17devel Lines: 126 136 92.6 %
Date: 2024-04-22 21:11:44 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) 1996-2024, 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/tablecmds.h"
      21             : #include "commands/view.h"
      22             : #include "nodes/makefuncs.h"
      23             : #include "nodes/nodeFuncs.h"
      24             : #include "parser/analyze.h"
      25             : #include "parser/parse_relation.h"
      26             : #include "rewrite/rewriteDefine.h"
      27             : #include "rewrite/rewriteHandler.h"
      28             : #include "rewrite/rewriteSupport.h"
      29             : #include "utils/builtins.h"
      30             : #include "utils/lsyscache.h"
      31             : #include "utils/rel.h"
      32             : 
      33             : static void checkViewColumns(TupleDesc newdesc, TupleDesc olddesc);
      34             : 
      35             : /*---------------------------------------------------------------------
      36             :  * DefineVirtualRelation
      37             :  *
      38             :  * Create a view relation and use the rules system to store the query
      39             :  * for the view.
      40             :  *
      41             :  * EventTriggerAlterTableStart must have been called already.
      42             :  *---------------------------------------------------------------------
      43             :  */
      44             : static ObjectAddress
      45       13606 : DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
      46             :                       List *options, Query *viewParse)
      47             : {
      48             :     Oid         viewOid;
      49             :     LOCKMODE    lockmode;
      50       13606 :     CreateStmt *createStmt = makeNode(CreateStmt);
      51             :     List       *attrList;
      52             :     ListCell   *t;
      53             : 
      54             :     /*
      55             :      * create a list of ColumnDef nodes based on the names and types of the
      56             :      * (non-junk) targetlist items from the view's SELECT list.
      57             :      */
      58       13606 :     attrList = NIL;
      59      133828 :     foreach(t, tlist)
      60             :     {
      61      120222 :         TargetEntry *tle = (TargetEntry *) lfirst(t);
      62             : 
      63      120222 :         if (!tle->resjunk)
      64             :         {
      65      119704 :             ColumnDef  *def = makeColumnDef(tle->resname,
      66      119704 :                                             exprType((Node *) tle->expr),
      67      119704 :                                             exprTypmod((Node *) tle->expr),
      68      119704 :                                             exprCollation((Node *) tle->expr));
      69             : 
      70             :             /*
      71             :              * It's possible that the column is of a collatable type but the
      72             :              * collation could not be resolved, so double-check.
      73             :              */
      74      119704 :             if (type_is_collatable(exprType((Node *) tle->expr)))
      75             :             {
      76       65492 :                 if (!OidIsValid(def->collOid))
      77           0 :                     ereport(ERROR,
      78             :                             (errcode(ERRCODE_INDETERMINATE_COLLATION),
      79             :                              errmsg("could not determine which collation to use for view column \"%s\"",
      80             :                                     def->colname),
      81             :                              errhint("Use the COLLATE clause to set the collation explicitly.")));
      82             :             }
      83             :             else
      84             :                 Assert(!OidIsValid(def->collOid));
      85             : 
      86      119704 :             attrList = lappend(attrList, def);
      87             :         }
      88             :     }
      89             : 
      90             :     /*
      91             :      * Look up, check permissions on, and lock the creation namespace; also
      92             :      * check for a preexisting view with the same name.  This will also set
      93             :      * relation->relpersistence to RELPERSISTENCE_TEMP if the selected
      94             :      * namespace is temporary.
      95             :      */
      96       13606 :     lockmode = replace ? AccessExclusiveLock : NoLock;
      97       13606 :     (void) RangeVarGetAndCheckCreationNamespace(relation, lockmode, &viewOid);
      98             : 
      99       13594 :     if (OidIsValid(viewOid) && replace)
     100             :     {
     101             :         Relation    rel;
     102             :         TupleDesc   descriptor;
     103         224 :         List       *atcmds = NIL;
     104             :         AlterTableCmd *atcmd;
     105             :         ObjectAddress address;
     106             : 
     107             :         /* Relation is already locked, but we must build a relcache entry. */
     108         224 :         rel = relation_open(viewOid, NoLock);
     109             : 
     110             :         /* Make sure it *is* a view. */
     111         224 :         if (rel->rd_rel->relkind != RELKIND_VIEW)
     112           0 :             ereport(ERROR,
     113             :                     (errcode(ERRCODE_WRONG_OBJECT_TYPE),
     114             :                      errmsg("\"%s\" is not a view",
     115             :                             RelationGetRelationName(rel))));
     116             : 
     117             :         /* Also check it's not in use already */
     118         224 :         CheckTableNotInUse(rel, "CREATE OR REPLACE VIEW");
     119             : 
     120             :         /*
     121             :          * Due to the namespace visibility rules for temporary objects, we
     122             :          * should only end up replacing a temporary view with another
     123             :          * temporary view, and similarly for permanent views.
     124             :          */
     125             :         Assert(relation->relpersistence == rel->rd_rel->relpersistence);
     126             : 
     127             :         /*
     128             :          * Create a tuple descriptor to compare against the existing view, and
     129             :          * verify that the old column list is an initial prefix of the new
     130             :          * column list.
     131             :          */
     132         224 :         descriptor = BuildDescForRelation(attrList);
     133         224 :         checkViewColumns(descriptor, rel->rd_att);
     134             : 
     135             :         /*
     136             :          * If new attributes have been added, we must add pg_attribute entries
     137             :          * for them.  It is convenient (although overkill) to use the ALTER
     138             :          * TABLE ADD COLUMN infrastructure for this.
     139             :          *
     140             :          * Note that we must do this before updating the query for the view,
     141             :          * since the rules system requires that the correct view columns be in
     142             :          * place when defining the new rules.
     143             :          *
     144             :          * Also note that ALTER TABLE doesn't run parse transformation on
     145             :          * AT_AddColumnToView commands.  The ColumnDef we supply must be ready
     146             :          * to execute as-is.
     147             :          */
     148         194 :         if (list_length(attrList) > rel->rd_att->natts)
     149             :         {
     150             :             ListCell   *c;
     151          24 :             int         skip = rel->rd_att->natts;
     152             : 
     153          96 :             foreach(c, attrList)
     154             :             {
     155          72 :                 if (skip > 0)
     156             :                 {
     157          48 :                     skip--;
     158          48 :                     continue;
     159             :                 }
     160          24 :                 atcmd = makeNode(AlterTableCmd);
     161          24 :                 atcmd->subtype = AT_AddColumnToView;
     162          24 :                 atcmd->def = (Node *) lfirst(c);
     163          24 :                 atcmds = lappend(atcmds, atcmd);
     164             :             }
     165             : 
     166             :             /* EventTriggerAlterTableStart called by ProcessUtilitySlow */
     167          24 :             AlterTableInternal(viewOid, atcmds, true);
     168             : 
     169             :             /* Make the new view columns visible */
     170          24 :             CommandCounterIncrement();
     171             :         }
     172             : 
     173             :         /*
     174             :          * Update the query for the view.
     175             :          *
     176             :          * Note that we must do this before updating the view options, because
     177             :          * the new options may not be compatible with the old view query (for
     178             :          * example if we attempt to add the WITH CHECK OPTION, we require that
     179             :          * the new view be automatically updatable, but the old view may not
     180             :          * have been).
     181             :          */
     182         194 :         StoreViewQuery(viewOid, viewParse, replace);
     183             : 
     184             :         /* Make the new view query visible */
     185         194 :         CommandCounterIncrement();
     186             : 
     187             :         /*
     188             :          * Update the view's options.
     189             :          *
     190             :          * The new options list replaces the existing options list, even if
     191             :          * it's empty.
     192             :          */
     193         194 :         atcmd = makeNode(AlterTableCmd);
     194         194 :         atcmd->subtype = AT_ReplaceRelOptions;
     195         194 :         atcmd->def = (Node *) options;
     196         194 :         atcmds = list_make1(atcmd);
     197             : 
     198             :         /* EventTriggerAlterTableStart called by ProcessUtilitySlow */
     199         194 :         AlterTableInternal(viewOid, atcmds, true);
     200             : 
     201             :         /*
     202             :          * There is very little to do here to update the view's dependencies.
     203             :          * Most view-level dependency relationships, such as those on the
     204             :          * owner, schema, and associated composite type, aren't changing.
     205             :          * Because we don't allow changing type or collation of an existing
     206             :          * view column, those dependencies of the existing columns don't
     207             :          * change either, while the AT_AddColumnToView machinery took care of
     208             :          * adding such dependencies for new view columns.  The dependencies of
     209             :          * the view's query could have changed arbitrarily, but that was dealt
     210             :          * with inside StoreViewQuery.  What remains is only to check that
     211             :          * view replacement is allowed when we're creating an extension.
     212             :          */
     213         194 :         ObjectAddressSet(address, RelationRelationId, viewOid);
     214             : 
     215         194 :         recordDependencyOnCurrentExtension(&address, true);
     216             : 
     217             :         /*
     218             :          * Seems okay, so return the OID of the pre-existing view.
     219             :          */
     220         192 :         relation_close(rel, NoLock);    /* keep the lock! */
     221             : 
     222         192 :         return address;
     223             :     }
     224             :     else
     225             :     {
     226             :         ObjectAddress address;
     227             : 
     228             :         /*
     229             :          * Set the parameters for keys/inheritance etc. All of these are
     230             :          * uninteresting for views...
     231             :          */
     232       13370 :         createStmt->relation = relation;
     233       13370 :         createStmt->tableElts = attrList;
     234       13370 :         createStmt->inhRelations = NIL;
     235       13370 :         createStmt->constraints = NIL;
     236       13370 :         createStmt->options = options;
     237       13370 :         createStmt->oncommit = ONCOMMIT_NOOP;
     238       13370 :         createStmt->tablespacename = NULL;
     239       13370 :         createStmt->if_not_exists = false;
     240             : 
     241             :         /*
     242             :          * Create the relation (this will error out if there's an existing
     243             :          * view, so we don't need more code to complain if "replace" is
     244             :          * false).
     245             :          */
     246       13370 :         address = DefineRelation(createStmt, RELKIND_VIEW, InvalidOid, NULL,
     247             :                                  NULL);
     248             :         Assert(address.objectId != InvalidOid);
     249             : 
     250             :         /* Make the new view relation visible */
     251       13352 :         CommandCounterIncrement();
     252             : 
     253             :         /* Store the query for the view */
     254       13352 :         StoreViewQuery(address.objectId, viewParse, replace);
     255             : 
     256       13352 :         return address;
     257             :     }
     258             : }
     259             : 
     260             : /*
     261             :  * Verify that the columns associated with proposed new view definition match
     262             :  * the columns of the old view.  This is similar to equalRowTypes(), with code
     263             :  * added to generate specific complaints.  Also, we allow the new view to have
     264             :  * more columns than the old.
     265             :  */
     266             : static void
     267         224 : checkViewColumns(TupleDesc newdesc, TupleDesc olddesc)
     268             : {
     269             :     int         i;
     270             : 
     271         224 :     if (newdesc->natts < olddesc->natts)
     272           6 :         ereport(ERROR,
     273             :                 (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
     274             :                  errmsg("cannot drop columns from view")));
     275             : 
     276         598 :     for (i = 0; i < olddesc->natts; i++)
     277             :     {
     278         404 :         Form_pg_attribute newattr = TupleDescAttr(newdesc, i);
     279         404 :         Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);
     280             : 
     281             :         /* XXX msg not right, but we don't support DROP COL on view anyway */
     282         404 :         if (newattr->attisdropped != oldattr->attisdropped)
     283           0 :             ereport(ERROR,
     284             :                     (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
     285             :                      errmsg("cannot drop columns from view")));
     286             : 
     287         404 :         if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)
     288           6 :             ereport(ERROR,
     289             :                     (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
     290             :                      errmsg("cannot change name of view column \"%s\" to \"%s\"",
     291             :                             NameStr(oldattr->attname),
     292             :                             NameStr(newattr->attname)),
     293             :                      errhint("Use ALTER VIEW ... RENAME COLUMN ... to change name of view column instead.")));
     294             : 
     295             :         /*
     296             :          * We cannot allow type, typmod, or collation to change, since these
     297             :          * properties may be embedded in Vars of other views/rules referencing
     298             :          * this one.  Other column attributes can be ignored.
     299             :          */
     300         398 :         if (newattr->atttypid != oldattr->atttypid ||
     301         392 :             newattr->atttypmod != oldattr->atttypmod)
     302          12 :             ereport(ERROR,
     303             :                     (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
     304             :                      errmsg("cannot change data type of view column \"%s\" from %s to %s",
     305             :                             NameStr(oldattr->attname),
     306             :                             format_type_with_typemod(oldattr->atttypid,
     307             :                                                      oldattr->atttypmod),
     308             :                             format_type_with_typemod(newattr->atttypid,
     309             :                                                      newattr->atttypmod))));
     310             : 
     311             :         /*
     312             :          * At this point, attcollations should be both valid or both invalid,
     313             :          * so applying get_collation_name unconditionally should be fine.
     314             :          */
     315         386 :         if (newattr->attcollation != oldattr->attcollation)
     316           6 :             ereport(ERROR,
     317             :                     (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
     318             :                      errmsg("cannot change collation of view column \"%s\" from \"%s\" to \"%s\"",
     319             :                             NameStr(oldattr->attname),
     320             :                             get_collation_name(oldattr->attcollation),
     321             :                             get_collation_name(newattr->attcollation))));
     322             :     }
     323             : 
     324             :     /*
     325             :      * We ignore the constraint fields.  The new view desc can't have any
     326             :      * constraints, and the only ones that could be on the old view are
     327             :      * defaults, which we are happy to leave in place.
     328             :      */
     329         194 : }
     330             : 
     331             : static void
     332       13984 : DefineViewRules(Oid viewOid, Query *viewParse, bool replace)
     333             : {
     334             :     /*
     335             :      * Set up the ON SELECT rule.  Since the query has already been through
     336             :      * parse analysis, we use DefineQueryRewrite() directly.
     337             :      */
     338       13984 :     DefineQueryRewrite(pstrdup(ViewSelectRuleName),
     339             :                        viewOid,
     340             :                        NULL,
     341             :                        CMD_SELECT,
     342             :                        true,
     343             :                        replace,
     344       13984 :                        list_make1(viewParse));
     345             : 
     346             :     /*
     347             :      * Someday: automatic ON INSERT, etc
     348             :      */
     349       13984 : }
     350             : 
     351             : /*
     352             :  * DefineView
     353             :  *      Execute a CREATE VIEW command.
     354             :  */
     355             : ObjectAddress
     356       13630 : DefineView(ViewStmt *stmt, const char *queryString,
     357             :            int stmt_location, int stmt_len)
     358             : {
     359             :     RawStmt    *rawstmt;
     360             :     Query      *viewParse;
     361             :     RangeVar   *view;
     362             :     ListCell   *cell;
     363             :     bool        check_option;
     364             :     ObjectAddress address;
     365             : 
     366             :     /*
     367             :      * Run parse analysis to convert the raw parse tree to a Query.  Note this
     368             :      * also acquires sufficient locks on the source table(s).
     369             :      */
     370       13630 :     rawstmt = makeNode(RawStmt);
     371       13630 :     rawstmt->stmt = stmt->query;
     372       13630 :     rawstmt->stmt_location = stmt_location;
     373       13630 :     rawstmt->stmt_len = stmt_len;
     374             : 
     375       13630 :     viewParse = parse_analyze_fixedparams(rawstmt, queryString, NULL, 0, NULL);
     376             : 
     377             :     /*
     378             :      * The grammar should ensure that the result is a single SELECT Query.
     379             :      * However, it doesn't forbid SELECT INTO, so we have to check for that.
     380             :      */
     381       13612 :     if (!IsA(viewParse, Query))
     382           0 :         elog(ERROR, "unexpected parse analysis result");
     383       13612 :     if (viewParse->utilityStmt != NULL &&
     384           6 :         IsA(viewParse->utilityStmt, CreateTableAsStmt))
     385           6 :         ereport(ERROR,
     386             :                 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
     387             :                  errmsg("views must not contain SELECT INTO")));
     388       13606 :     if (viewParse->commandType != CMD_SELECT)
     389           0 :         elog(ERROR, "unexpected parse analysis result");
     390             : 
     391             :     /*
     392             :      * Check for unsupported cases.  These tests are redundant with ones in
     393             :      * DefineQueryRewrite(), but that function will complain about a bogus ON
     394             :      * SELECT rule, and we'd rather the message complain about a view.
     395             :      */
     396       13606 :     if (viewParse->hasModifyingCTE)
     397           0 :         ereport(ERROR,
     398             :                 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
     399             :                  errmsg("views must not contain data-modifying statements in WITH")));
     400             : 
     401             :     /*
     402             :      * If the user specified the WITH CHECK OPTION, add it to the list of
     403             :      * reloptions.
     404             :      */
     405       13606 :     if (stmt->withCheckOption == LOCAL_CHECK_OPTION)
     406          24 :         stmt->options = lappend(stmt->options,
     407          24 :                                 makeDefElem("check_option",
     408          24 :                                             (Node *) makeString("local"), -1));
     409       13582 :     else if (stmt->withCheckOption == CASCADED_CHECK_OPTION)
     410          96 :         stmt->options = lappend(stmt->options,
     411          96 :                                 makeDefElem("check_option",
     412          96 :                                             (Node *) makeString("cascaded"), -1));
     413             : 
     414             :     /*
     415             :      * Check that the view is auto-updatable if WITH CHECK OPTION was
     416             :      * specified.
     417             :      */
     418       13606 :     check_option = false;
     419             : 
     420       14194 :     foreach(cell, stmt->options)
     421             :     {
     422         588 :         DefElem    *defel = (DefElem *) lfirst(cell);
     423             : 
     424         588 :         if (strcmp(defel->defname, "check_option") == 0)
     425         122 :             check_option = true;
     426             :     }
     427             : 
     428             :     /*
     429             :      * If the check option is specified, look to see if the view is actually
     430             :      * auto-updatable or not.
     431             :      */
     432       13606 :     if (check_option)
     433             :     {
     434             :         const char *view_updatable_error =
     435         122 :             view_query_is_auto_updatable(viewParse, true);
     436             : 
     437         122 :         if (view_updatable_error)
     438           0 :             ereport(ERROR,
     439             :                     (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
     440             :                      errmsg("WITH CHECK OPTION is supported only on automatically updatable views"),
     441             :                      errhint("%s", _(view_updatable_error))));
     442             :     }
     443             : 
     444             :     /*
     445             :      * If a list of column names was given, run through and insert these into
     446             :      * the actual query tree. - thomas 2000-03-08
     447             :      */
     448       13606 :     if (stmt->aliases != NIL)
     449             :     {
     450          56 :         ListCell   *alist_item = list_head(stmt->aliases);
     451             :         ListCell   *targetList;
     452             : 
     453          80 :         foreach(targetList, viewParse->targetList)
     454             :         {
     455          80 :             TargetEntry *te = lfirst_node(TargetEntry, targetList);
     456             : 
     457             :             /* junk columns don't get aliases */
     458          80 :             if (te->resjunk)
     459           0 :                 continue;
     460          80 :             te->resname = pstrdup(strVal(lfirst(alist_item)));
     461          80 :             alist_item = lnext(stmt->aliases, alist_item);
     462          80 :             if (alist_item == NULL)
     463          56 :                 break;          /* done assigning aliases */
     464             :         }
     465             : 
     466          56 :         if (alist_item != NULL)
     467           0 :             ereport(ERROR,
     468             :                     (errcode(ERRCODE_SYNTAX_ERROR),
     469             :                      errmsg("CREATE VIEW specifies more column "
     470             :                             "names than columns")));
     471             :     }
     472             : 
     473             :     /* Unlogged views are not sensible. */
     474       13606 :     if (stmt->view->relpersistence == RELPERSISTENCE_UNLOGGED)
     475           0 :         ereport(ERROR,
     476             :                 (errcode(ERRCODE_SYNTAX_ERROR),
     477             :                  errmsg("views cannot be unlogged because they do not have storage")));
     478             : 
     479             :     /*
     480             :      * If the user didn't explicitly ask for a temporary view, check whether
     481             :      * we need one implicitly.  We allow TEMP to be inserted automatically as
     482             :      * long as the CREATE command is consistent with that --- no explicit
     483             :      * schema name.
     484             :      */
     485       13606 :     view = copyObject(stmt->view);   /* don't corrupt original command */
     486       13606 :     if (view->relpersistence == RELPERSISTENCE_PERMANENT
     487       13354 :         && isQueryUsingTempRelation(viewParse))
     488             :     {
     489         108 :         view->relpersistence = RELPERSISTENCE_TEMP;
     490         108 :         ereport(NOTICE,
     491             :                 (errmsg("view \"%s\" will be a temporary view",
     492             :                         view->relname)));
     493             :     }
     494             : 
     495             :     /*
     496             :      * Create the view relation
     497             :      *
     498             :      * NOTE: if it already exists and replace is false, the xact will be
     499             :      * aborted.
     500             :      */
     501       13606 :     address = DefineVirtualRelation(view, viewParse->targetList,
     502       13606 :                                     stmt->replace, stmt->options, viewParse);
     503             : 
     504       13544 :     return address;
     505             : }
     506             : 
     507             : /*
     508             :  * Use the rules system to store the query for the view.
     509             :  */
     510             : void
     511       13984 : StoreViewQuery(Oid viewOid, Query *viewParse, bool replace)
     512             : {
     513             :     /*
     514             :      * Now create the rules associated with the view.
     515             :      */
     516       13984 :     DefineViewRules(viewOid, viewParse, replace);
     517       13984 : }

Generated by: LCOV version 1.14