YugabyteDB (2.13.1.0-b60, 21121d69985fbf76aa6958d8f04a9bfa936293b5)

/*-------------------------------------------------------------------------

 *

 * view.c

 *    use rewrite rules to construct views

 *

 * Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group

 * Portions Copyright (c) 1994, Regents of the University of California

 *

 *

 * IDENTIFICATION

 *    src/backend/commands/view.c

 *

 *-------------------------------------------------------------------------

 */

#include "postgres.h"

#include "access/heapam.h"

#include "access/xact.h"

#include "catalog/namespace.h"

#include "commands/defrem.h"

#include "commands/tablecmds.h"

#include "commands/view.h"

#include "miscadmin.h"

#include "nodes/makefuncs.h"

#include "nodes/nodeFuncs.h"

#include "parser/analyze.h"

#include "parser/parse_relation.h"

#include "rewrite/rewriteDefine.h"

#include "rewrite/rewriteManip.h"

#include "rewrite/rewriteHandler.h"

#include "rewrite/rewriteSupport.h"

#include "utils/acl.h"

#include "utils/builtins.h"

#include "utils/lsyscache.h"

#include "utils/rel.h"

#include "utils/syscache.h"

/* YB includes. */

#include "catalog/catalog.h"

#include "pg_yb_utils.h"

static void checkViewTupleDesc(TupleDesc newdesc, TupleDesc olddesc);

/*---------------------------------------------------------------------

 * Validator for "check_option" reloption on views. The allowed values

 * are "local" and "cascaded".

 */

void

validateWithCheckOption(const char *value)

{

  if (value == NULL ||

    (strcmp(value, "local") != 0 &&

     strcmp(value, "cascaded") != 0))

  {

    ereport(ERROR,

        (errcode(ERRCODE_INVALID_PARAMETER_VALUE),

         errmsg("invalid value for \"check_option\" option"),

         errdetail("Valid values are \"local\" and \"cascaded\".")));

  }

}

/*---------------------------------------------------------------------

 * DefineVirtualRelation

 *

 * Create a view relation and use the rules system to store the query

 * for the view.

 *

 * EventTriggerAlterTableStart must have been called already.

 *---------------------------------------------------------------------

 */

static ObjectAddress

DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,

            List *options, Query *viewParse)

{

  Oid     viewOid;

  LOCKMODE  lockmode;

  CreateStmt *createStmt = makeNode(CreateStmt);

  List     *attrList;

  ListCell   *t;

  /*

   * create a list of ColumnDef nodes based on the names and types of the

   * (non-junk) targetlist items from the view's SELECT list.

   */

  attrList = NIL;

  foreach(t, tlist)

  {

    TargetEntry *tle = (TargetEntry *) lfirst(t);

    if (!tle->resjunk)

    {

      ColumnDef  *def = makeColumnDef(tle->resname,

                      exprType((Node *) tle->expr),

                      exprTypmod((Node *) tle->expr),

                      exprCollation((Node *) tle->expr));

      /*

       * It's possible that the column is of a collatable type but the

       * collation could not be resolved, so double-check.

       */

      if (type_is_collatable(exprType((Node *) tle->expr)))

      {

        if (!OidIsValid(def->collOid))

          ereport(ERROR,

              (errcode(ERRCODE_INDETERMINATE_COLLATION),

               errmsg("could not determine which collation to use for view column \"%s\"",

                  def->colname),

               errhint("Use the COLLATE clause to set the collation explicitly.")));

      }

      else

        Assert(!OidIsValid(def->collOid));

      attrList = lappend(attrList, def);

    }

  }

  if (attrList == NIL)

    ereport(ERROR,

        (errcode(ERRCODE_INVALID_TABLE_DEFINITION),

         errmsg("view must have at least one column")));

  /*

   * Look up, check permissions on, and lock the creation namespace; also

   * check for a preexisting view with the same name.  This will also set

   * relation->relpersistence to RELPERSISTENCE_TEMP if the selected

   * namespace is temporary.

   */

  lockmode = replace ? 
AccessExclusiveLock11
 : 
NoLock464
;

  (void) RangeVarGetAndCheckCreationNamespace(relation, lockmode, &viewOid);

  /*

   * In YB, system views can only be created during initdb and YSQL upgrade.

   */

  if (IsYugaByteEnabled() &&

    !IsYsqlUpgrade &&

    
!462
IsBootstrapProcessingMode462
() &&

    
!YBIsPreparingTemplates()462
 &&

    
YbIsSystemNamespaceByName(relation->schemaname)222
)

  {

    ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),

        errmsg("system views cannot be created outside of YSQL upgrade")));

  }

  if (OidIsValid(viewOid) && 
replace2
)

  {

    Relation  rel;

    TupleDesc descriptor;

    List     *atcmds = NIL;

    AlterTableCmd *atcmd;

    ObjectAddress address;

    /* Relation is already locked, but we must build a relcache entry. */

    rel = relation_open(viewOid, NoLock);

    /* Make sure it *is* a view. */

    if (rel->rd_rel->relkind != RELKIND_VIEW)

      ereport(ERROR,

          (errcode(ERRCODE_WRONG_OBJECT_TYPE),

           errmsg("\"%s\" is not a view",

              RelationGetRelationName(rel))));

    /* Also check it's not in use already */

    CheckTableNotInUse(rel, "CREATE OR REPLACE VIEW");

    /*

     * Due to the namespace visibility rules for temporary objects, we

     * should only end up replacing a temporary view with another

     * temporary view, and similarly for permanent views.

     */

    Assert(relation->relpersistence == rel->rd_rel->relpersistence);

    /*

     * Create a tuple descriptor to compare against the existing view, and

     * verify that the old column list is an initial prefix of the new

     * column list.

     */

    descriptor = BuildDescForRelation(attrList);

    checkViewTupleDesc(descriptor, rel->rd_att);

    /*

     * If new attributes have been added, we must add pg_attribute entries

     * for them.  It is convenient (although overkill) to use the ALTER

     * TABLE ADD COLUMN infrastructure for this.

     *

     * Note that we must do this before updating the query for the view,

     * since the rules system requires that the correct view columns be in

     * place when defining the new rules.

     */

    if (list_length(attrList) > rel->rd_att->natts)

    {

      ListCell   *c;

      int     skip = rel->rd_att->natts;

      foreach(c, attrList)

      {

        if (skip > 0)

        {

          skip--;

          continue;

        }

        atcmd = makeNode(AlterTableCmd);

        atcmd->subtype = AT_AddColumnToView;

        atcmd->def = (Node *) lfirst(c);

        atcmds = lappend(atcmds, atcmd);

      }

      /* EventTriggerAlterTableStart called by ProcessUtilitySlow */

      AlterTableInternal(viewOid, atcmds, true);

      /* Make the new view columns visible */

      CommandCounterIncrement();

    }

    /*

     * Update the query for the view.

     *

     * Note that we must do this before updating the view options, because

     * the new options may not be compatible with the old view query (for

     * example if we attempt to add the WITH CHECK OPTION, we require that

     * the new view be automatically updatable, but the old view may not

     * have been).

     */

    StoreViewQuery(viewOid, viewParse, replace);

    /* Make the new view query visible */

    CommandCounterIncrement();

    /*

     * Finally update the view options.

     *

     * The new options list replaces the existing options list, even if

     * it's empty.

     */

    atcmd = makeNode(AlterTableCmd);

    atcmd->subtype = AT_ReplaceRelOptions;

    atcmd->def = (Node *) options;

    atcmds = list_make1(atcmd);

    /* EventTriggerAlterTableStart called by ProcessUtilitySlow */

    AlterTableInternal(viewOid, atcmds, true);

    ObjectAddressSet(address, RelationRelationId, viewOid);

    /*

     * Seems okay, so return the OID of the pre-existing view.

     */

    relation_close(rel, NoLock);  /* keep the lock! */

    return address;

  }

  else

  {

    ObjectAddress address;

    /*

     * Set the parameters for keys/inheritance etc. All of these are

     * uninteresting for views...

     */

    createStmt->relation = relation;

    createStmt->tableElts = attrList;

    createStmt->inhRelations = NIL;

    createStmt->constraints = NIL;

    createStmt->options = options;

    createStmt->oncommit = ONCOMMIT_NOOP;

    createStmt->tablespacename = NULL;

    createStmt->if_not_exists = false;

    /*

     * Create the relation (this will error out if there's an existing

     * view, so we don't need more code to complain if "replace" is

     * false).

     */

    address = DefineRelation(createStmt, RELKIND_VIEW, InvalidOid, NULL,

                 NULL);

    Assert(address.objectId != InvalidOid);

    /* Make the new view relation visible */

    CommandCounterIncrement();

    /* Store the query for the view */

    StoreViewQuery(address.objectId, viewParse, replace);

    return address;

  }

}

/*

 * Verify that tupledesc associated with proposed new view definition

 * matches tupledesc of old view.  This is basically a cut-down version

 * of equalTupleDescs(), with code added to generate specific complaints.

 * Also, we allow the new tupledesc to have more columns than the old.

 */

static void

checkViewTupleDesc(TupleDesc newdesc, TupleDesc olddesc)

{

  int     i;

  if (newdesc->natts < olddesc->natts)

    ereport(ERROR,

        (errcode(ERRCODE_INVALID_TABLE_DEFINITION),

         errmsg("cannot drop columns from view")));

  /* we can ignore tdhasoid */

  
for (i = 0; 2
i < olddesc->natts; 
i++2
)

  {

    Form_pg_attribute newattr = TupleDescAttr(newdesc, i);

    Form_pg_attribute oldattr = TupleDescAttr(olddesc, i);

    /* XXX msg not right, but we don't support DROP COL on view anyway */

    if (newattr->attisdropped != oldattr->attisdropped)

      ereport(ERROR,

          (errcode(ERRCODE_INVALID_TABLE_DEFINITION),

           errmsg("cannot drop columns from view")));

    if (strcmp(NameStr(newattr->attname), NameStr(oldattr->attname)) != 0)

      ereport(ERROR,

          (errcode(ERRCODE_INVALID_TABLE_DEFINITION),

           errmsg("cannot change name of view column \"%s\" to \"%s\"",

              NameStr(oldattr->attname),

              NameStr(newattr->attname))));

    /* XXX would it be safe to allow atttypmod to change?  Not sure */

    if (newattr->atttypid != oldattr->atttypid ||

      newattr->atttypmod != oldattr->atttypmod)

      ereport(ERROR,

          (errcode(ERRCODE_INVALID_TABLE_DEFINITION),

           errmsg("cannot change data type of view column \"%s\" from %s to %s",

              NameStr(oldattr->attname),

              format_type_with_typemod(oldattr->atttypid,

                           oldattr->atttypmod),

              format_type_with_typemod(newattr->atttypid,

                           newattr->atttypmod))));

    /* We can ignore the remaining attributes of an attribute... */

  }

  /*

   * We ignore the constraint fields.  The new view desc can't have any

   * constraints, and the only ones that could be on the old view are

   * defaults, which we are happy to leave in place.

   */

}

static void

DefineViewRules(Oid viewOid, Query *viewParse, bool replace)

{

  /*

   * Set up the ON SELECT rule.  Since the query has already been through

   * parse analysis, we use DefineQueryRewrite() directly.

   */

  DefineQueryRewrite(pstrdup(ViewSelectRuleName),

             viewOid,

             NULL,

             CMD_SELECT,

             true,

             replace,

             list_make1(viewParse));

  /*

   * Someday: automatic ON INSERT, etc

   */

}

/*---------------------------------------------------------------

 * UpdateRangeTableOfViewParse

 *

 * Update the range table of the given parsetree.

 * This update consists of adding two new entries IN THE BEGINNING

 * of the range table (otherwise the rule system will die a slow,

 * horrible and painful death, and we do not want that now, do we?)

 * one for the OLD relation and one for the NEW one (both of

 * them refer in fact to the "view" relation).

 *

 * Of course we must also increase the 'varnos' of all the Var nodes

 * by 2...

 *

 * These extra RT entries are not actually used in the query,

 * except for run-time permission checking.

 *---------------------------------------------------------------

 */

static Query *

UpdateRangeTableOfViewParse(Oid viewOid, Query *viewParse)

{

  Relation  viewRel;

  List     *new_rt;

  RangeTblEntry *rt_entry1,

         *rt_entry2;

  ParseState *pstate;

  /*

   * Make a copy of the given parsetree.  It's not so much that we don't

   * want to scribble on our input, it's that the parser has a bad habit of

   * outputting multiple links to the same subtree for constructs like

   * BETWEEN, and we mustn't have OffsetVarNodes increment the varno of a

   * Var node twice.  copyObject will expand any multiply-referenced subtree

   * into multiple copies.

   */

  viewParse = copyObject(viewParse);

  /* Create a dummy ParseState for addRangeTableEntryForRelation */

  pstate = make_parsestate(NULL);

  /* need to open the rel for addRangeTableEntryForRelation */

  viewRel = relation_open(viewOid, AccessShareLock);

  /*

   * Create the 2 new range table entries and form the new range table...

   * OLD first, then NEW....

   */

  rt_entry1 = addRangeTableEntryForRelation(pstate, viewRel,

                        makeAlias("old", NIL),

                        false, false);

  rt_entry2 = addRangeTableEntryForRelation(pstate, viewRel,

                        makeAlias("new", NIL),

                        false, false);

  /* Must override addRangeTableEntry's default access-check flags */

  rt_entry1->requiredPerms = 0;

  rt_entry2->requiredPerms = 0;

  new_rt = lcons(rt_entry1, lcons(rt_entry2, viewParse->rtable));

  viewParse->rtable = new_rt;

  /*

   * Now offset all var nodes by 2, and jointree RT indexes too.

   */

  OffsetVarNodes((Node *) viewParse, 2, 0);

  relation_close(viewRel, AccessShareLock);

  return viewParse;

}

/*

 * DefineView

 *    Execute a CREATE VIEW command.

 */

ObjectAddress

DefineView(ViewStmt *stmt, const char *queryString,

       int stmt_location, int stmt_len)

{

  RawStmt    *rawstmt;

  Query    *viewParse;

  RangeVar   *view;

  ListCell   *cell;

  bool    check_option;

  ObjectAddress address;

  /*

   * Run parse analysis to convert the raw parse tree to a Query.  Note this

   * also acquires sufficient locks on the source table(s).

   *

   * Since parse analysis scribbles on its input, copy the raw parse tree;

   * this ensures we don't corrupt a prepared statement, for example.

   */

  rawstmt = makeNode(RawStmt);

  rawstmt->stmt = (Node *) copyObject(stmt->query);

  rawstmt->stmt_location = stmt_location;

  rawstmt->stmt_len = stmt_len;

  viewParse = parse_analyze(rawstmt, queryString, NULL, 0, NULL);

  /*

   * The grammar should ensure that the result is a single SELECT Query.

   * However, it doesn't forbid SELECT INTO, so we have to check for that.

   */

  if (!IsA(viewParse, Query))

    elog(ERROR, "unexpected parse analysis result");

  if (viewParse->utilityStmt != NULL &&

    
IsA0
(viewParse->utilityStmt, CreateTableAsStmt))

    ereport(ERROR,

        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),

         errmsg("views must not contain SELECT INTO")));

  if (viewParse->commandType != CMD_SELECT)

    elog(ERROR, "unexpected parse analysis result");

  /*

   * Check for unsupported cases.  These tests are redundant with ones in

   * DefineQueryRewrite(), but that function will complain about a bogus ON

   * SELECT rule, and we'd rather the message complain about a view.

   */

  if (viewParse->hasModifyingCTE)

    ereport(ERROR,

        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),

         errmsg("views must not contain data-modifying statements in WITH")));

  /*

   * If the user specified the WITH CHECK OPTION, add it to the list of

   * reloptions.

   */

  if (stmt->withCheckOption == LOCAL_CHECK_OPTION)

    stmt->options = lappend(stmt->options,

                makeDefElem("check_option",

                      (Node *) makeString("local"), -1));

  else if (stmt->withCheckOption == CASCADED_CHECK_OPTION)

    stmt->options = lappend(stmt->options,

                makeDefElem("check_option",

                      (Node *) makeString("cascaded"), -1));

  /*

   * Check that the view is auto-updatable if WITH CHECK OPTION was

   * specified.

   */

  check_option = false;

  foreach(cell, stmt->options)

  {

    DefElem    *defel = (DefElem *) lfirst(cell);

    if (strcmp(defel->defname, "check_option") == 0)

      check_option = true;

  }

  /*

   * If the check option is specified, look to see if the view is actually

   * auto-updatable or not.

   */

  if (check_option)

  {

    const char *view_updatable_error =

    view_query_is_auto_updatable(viewParse, true);

    if (view_updatable_error)

      ereport(ERROR,

          (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),

           errmsg("WITH CHECK OPTION is supported only on automatically updatable views"),

           errhint("%s", _(view_updatable_error))));

  }

  /*

   * If a list of column names was given, run through and insert these into

   * the actual query tree. - thomas 2000-03-08

   */

  if (stmt->aliases != NIL)

  {

    ListCell   *alist_item = list_head(stmt->aliases);

    ListCell   *targetList;

    foreach(targetList, viewParse->targetList)

    {

      TargetEntry *te = lfirst_node(TargetEntry, targetList);

      /* junk columns don't get aliases */

      if (te->resjunk)

        continue;

      te->resname = pstrdup(strVal(lfirst(alist_item)));

      alist_item = lnext(alist_item);

      if (alist_item == NULL)

        break;     /* done assigning aliases */

    }

    if (alist_item != NULL)

      ereport(ERROR,

          (errcode(ERRCODE_SYNTAX_ERROR),

           errmsg("CREATE VIEW specifies more column "

              "names than columns")));

  }

  /* Unlogged views are not sensible. */

  if (stmt->view->relpersistence == RELPERSISTENCE_UNLOGGED)

    ereport(ERROR,

        (errcode(ERRCODE_SYNTAX_ERROR),

         errmsg("views cannot be unlogged because they do not have storage")));

  /*

   * If the user didn't explicitly ask for a temporary view, check whether

   * we need one implicitly.  We allow TEMP to be inserted automatically as

   * long as the CREATE command is consistent with that --- no explicit

   * schema name.

   */

  view = copyObject(stmt->view); /* don't corrupt original command */

  if (view->relpersistence == RELPERSISTENCE_PERMANENT

    && 
isQueryUsingTempRelation(viewParse)463
)

  {

    view->relpersistence = RELPERSISTENCE_TEMP;

    ereport(NOTICE,

        (errmsg("view \"%s\" will be a temporary view",

            view->relname)));

  }

  /*

   * Create the view relation

   *

   * NOTE: if it already exists and replace is false, the xact will be

   * aborted.

   */

  address = DefineVirtualRelation(view, viewParse->targetList,

                  stmt->replace, stmt->options, viewParse);

  return address;

}

/*

 * Use the rules system to store the query for the view.

 */

void

StoreViewQuery(Oid viewOid, Query *viewParse, bool replace)

{

  /*

   * The range table of 'viewParse' does not contain entries for the "OLD"

   * and "NEW" relations. So... add them!

   */

  viewParse = UpdateRangeTableOfViewParse(viewOid, viewParse);

  /*

   * Now create the rules associated with the view.

   */

  DefineViewRules(viewOid, viewParse, replace);

}