569 lines
17 KiB
C
569 lines
17 KiB
C
/*-------------------------------------------------------------------------
|
|
*
|
|
* view.c
|
|
* use rewrite rules to construct views
|
|
*
|
|
* Portions Copyright (c) 1996-2019, 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/relation.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/rewriteHandler.h"
|
|
#include "rewrite/rewriteManip.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"
|
|
|
|
static void checkViewTupleDesc(TupleDesc newdesc, TupleDesc olddesc);
|
|
|
|
/*---------------------------------------------------------------------
|
|
* 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);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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 ? AccessExclusiveLock : NoLock;
|
|
(void) RangeVarGetAndCheckCreationNamespace(relation, lockmode, &viewOid);
|
|
|
|
if (OidIsValid(viewOid) && replace)
|
|
{
|
|
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")));
|
|
|
|
for (i = 0; i < olddesc->natts; i++)
|
|
{
|
|
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 locking and 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,
|
|
AccessShareLock,
|
|
makeAlias("old", NIL),
|
|
false, false);
|
|
rt_entry2 = addRangeTableEntryForRelation(pstate, viewRel,
|
|
AccessShareLock,
|
|
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 &&
|
|
IsA(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(stmt->aliases, 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))
|
|
{
|
|
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);
|
|
}
|