mirror of
https://git.postgresql.org/git/postgresql.git
synced 2024-09-08 13:29:20 +02:00
270 lines
7.2 KiB
C
270 lines
7.2 KiB
C
/*-------------------------------------------------------------------------
|
|
*
|
|
* view.c
|
|
* use rewrite rules to construct views
|
|
*
|
|
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
|
|
* Portions Copyright (c) 1994, Regents of the University of California
|
|
*
|
|
* $Id: view.c,v 1.58 2001/10/25 05:49:26 momjian Exp $
|
|
*
|
|
*-------------------------------------------------------------------------
|
|
*/
|
|
#include "postgres.h"
|
|
|
|
#include "access/xact.h"
|
|
#include "catalog/heap.h"
|
|
#include "commands/creatinh.h"
|
|
#include "commands/view.h"
|
|
#include "miscadmin.h"
|
|
#include "nodes/makefuncs.h"
|
|
#include "parser/parse_relation.h"
|
|
#include "parser/parse_type.h"
|
|
#include "rewrite/rewriteDefine.h"
|
|
#include "rewrite/rewriteManip.h"
|
|
#include "rewrite/rewriteRemove.h"
|
|
#include "rewrite/rewriteSupport.h"
|
|
|
|
|
|
/*---------------------------------------------------------------------
|
|
* DefineVirtualRelation
|
|
*
|
|
* Create the "view" relation.
|
|
* `DefineRelation' does all the work, we just provide the correct
|
|
* arguments!
|
|
*
|
|
* If the relation already exists, then 'DefineRelation' will abort
|
|
* the xact...
|
|
*---------------------------------------------------------------------
|
|
*/
|
|
static void
|
|
DefineVirtualRelation(char *relname, List *tlist)
|
|
{
|
|
CreateStmt *createStmt = makeNode(CreateStmt);
|
|
List *attrList,
|
|
*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 *entry = lfirst(t);
|
|
Resdom *res = entry->resdom;
|
|
|
|
if (!res->resjunk)
|
|
{
|
|
char *resname = res->resname;
|
|
char *restypename = typeidTypeName(res->restype);
|
|
ColumnDef *def = makeNode(ColumnDef);
|
|
TypeName *typename = makeNode(TypeName);
|
|
|
|
def->colname = pstrdup(resname);
|
|
|
|
typename->name = pstrdup(restypename);
|
|
typename->typmod = res->restypmod;
|
|
def->typename = typename;
|
|
|
|
def->is_not_null = false;
|
|
def->raw_default = NULL;
|
|
def->cooked_default = NULL;
|
|
def->constraints = NIL;
|
|
|
|
attrList = lappend(attrList, def);
|
|
}
|
|
}
|
|
|
|
if (attrList == NIL)
|
|
elog(ERROR, "attempted to define virtual relation with no attrs");
|
|
|
|
/*
|
|
* now create the parameters for keys/inheritance etc. All of them are
|
|
* nil...
|
|
*/
|
|
createStmt->relname = relname;
|
|
createStmt->tableElts = attrList;
|
|
createStmt->inhRelnames = NIL;
|
|
createStmt->constraints = NIL;
|
|
createStmt->istemp = false;
|
|
createStmt->hasoids = false;
|
|
|
|
/*
|
|
* finally create the relation...
|
|
*/
|
|
DefineRelation(createStmt, RELKIND_VIEW);
|
|
}
|
|
|
|
static RuleStmt *
|
|
FormViewRetrieveRule(char *viewName, Query *viewParse)
|
|
{
|
|
RuleStmt *rule;
|
|
char *rname;
|
|
Attr *attr;
|
|
|
|
/*
|
|
* Create a RuleStmt that corresponds to the suitable rewrite rule
|
|
* args for DefineQueryRewrite();
|
|
*/
|
|
rule = makeNode(RuleStmt);
|
|
rname = MakeRetrieveViewRuleName(viewName);
|
|
|
|
attr = makeNode(Attr);
|
|
attr->relname = pstrdup(viewName);
|
|
rule->rulename = pstrdup(rname);
|
|
rule->whereClause = NULL;
|
|
rule->event = CMD_SELECT;
|
|
rule->object = attr;
|
|
rule->instead = true;
|
|
rule->actions = makeList1(viewParse);
|
|
|
|
return rule;
|
|
}
|
|
|
|
static void
|
|
DefineViewRules(char *viewName, Query *viewParse)
|
|
{
|
|
RuleStmt *retrieve_rule;
|
|
|
|
#ifdef NOTYET
|
|
RuleStmt *replace_rule;
|
|
RuleStmt *append_rule;
|
|
RuleStmt *delete_rule;
|
|
#endif
|
|
|
|
retrieve_rule = FormViewRetrieveRule(viewName, viewParse);
|
|
|
|
#ifdef NOTYET
|
|
|
|
replace_rule = FormViewReplaceRule(viewName, viewParse);
|
|
append_rule = FormViewAppendRule(viewName, viewParse);
|
|
delete_rule = FormViewDeleteRule(viewName, viewParse);
|
|
#endif
|
|
|
|
DefineQueryRewrite(retrieve_rule);
|
|
|
|
#ifdef NOTYET
|
|
DefineQueryRewrite(replace_rule);
|
|
DefineQueryRewrite(append_rule);
|
|
DefineQueryRewrite(delete_rule);
|
|
#endif
|
|
|
|
}
|
|
|
|
/*---------------------------------------------------------------
|
|
* 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(char *viewName, Query *viewParse)
|
|
{
|
|
List *new_rt;
|
|
RangeTblEntry *rt_entry1,
|
|
*rt_entry2;
|
|
|
|
/*
|
|
* 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 = (Query *) copyObject(viewParse);
|
|
|
|
/*
|
|
* Create the 2 new range table entries and form the new range
|
|
* table... OLD first, then NEW....
|
|
*/
|
|
rt_entry1 = addRangeTableEntry(NULL, viewName,
|
|
makeAttr("*OLD*", NULL),
|
|
false, false);
|
|
rt_entry2 = addRangeTableEntry(NULL, viewName,
|
|
makeAttr("*NEW*", NULL),
|
|
false, false);
|
|
/* Must override addRangeTableEntry's default access-check flags */
|
|
rt_entry1->checkForRead = false;
|
|
rt_entry2->checkForRead = false;
|
|
|
|
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);
|
|
|
|
return viewParse;
|
|
}
|
|
|
|
/*-------------------------------------------------------------------
|
|
* DefineView
|
|
*
|
|
* - takes a "viewname", "parsetree" pair and then
|
|
* 1) construct the "virtual" relation
|
|
* 2) commit the command but NOT the transaction,
|
|
* so that the relation exists
|
|
* before the rules are defined.
|
|
* 2) define the "n" rules specified in the PRS2 paper
|
|
* over the "virtual" relation
|
|
*-------------------------------------------------------------------
|
|
*/
|
|
void
|
|
DefineView(char *viewName, Query *viewParse)
|
|
{
|
|
/*
|
|
* Create the "view" relation NOTE: if it already exists, the xact
|
|
* will be aborted.
|
|
*/
|
|
DefineVirtualRelation(viewName, viewParse->targetList);
|
|
|
|
/*
|
|
* The relation we have just created is not visible to any other
|
|
* commands running with the same transaction & command id. So,
|
|
* increment the command id counter (but do NOT pfree any memory!!!!)
|
|
*/
|
|
CommandCounterIncrement();
|
|
|
|
/*
|
|
* The range table of 'viewParse' does not contain entries for the
|
|
* "OLD" and "NEW" relations. So... add them!
|
|
*/
|
|
viewParse = UpdateRangeTableOfViewParse(viewName, viewParse);
|
|
|
|
/*
|
|
* Now create the rules associated with the view.
|
|
*/
|
|
DefineViewRules(viewName, viewParse);
|
|
}
|
|
|
|
/*------------------------------------------------------------------
|
|
* RemoveView
|
|
*
|
|
* Remove a view given its name
|
|
*------------------------------------------------------------------
|
|
*/
|
|
void
|
|
RemoveView(char *viewName)
|
|
{
|
|
/*
|
|
* We just have to drop the relation; the associated rules will be
|
|
* cleaned up automatically.
|
|
*/
|
|
heap_drop_with_catalog(viewName, allowSystemTableMods);
|
|
}
|