parse_relation.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

	rte->rtekind = RTE_JOIN;
	rte->relid = InvalidOid;
	rte->subquery = NULL;
	rte->jointype = jointype;
	rte->joinaliasvars = aliasvars;
	rte->alias = alias;

	eref = alias ? (Alias *) copyObject(alias) : makeAlias("unnamed_join", NIL);
	numaliases = list_length(eref->colnames);

	/* fill in any unspecified alias columns */
	if (numaliases < list_length(colnames))
		eref->colnames = list_concat(eref->colnames,
									 list_copy_tail(colnames, numaliases));

	rte->eref = eref;

	/*----------
	 * Flags:
	 * - this RTE should be expanded to include descendant tables,
	 * - this RTE is in the FROM clause,
	 * - this RTE should be checked for appropriate access rights.
	 *
	 * Joins are never checked for access rights.
	 *----------
	 */
	rte->inh = false;			/* never true for joins */
	rte->inFromCl = inFromCl;

	rte->requiredPerms = 0;
	rte->checkAsUser = InvalidOid;

	/*
	 * Add completed RTE to pstate's range table list, but not to join list
	 * nor namespace --- caller must do that if appropriate.
	 */
	if (pstate != NULL)
		pstate->p_rtable = lappend(pstate->p_rtable, rte);

	return rte;
}

/*
 * Has the specified refname been selected FOR UPDATE/FOR SHARE?
 */
static bool
isLockedRel(ParseState *pstate, char *refname)
{
	/* Outer loop to check parent query levels as well as this one */
	while (pstate != NULL)
	{
		if (pstate->p_locking_clause)
		{
			if (pstate->p_locking_clause->lockedRels == NIL)
			{
				/* all tables used in query */
				return true;
			}
			else
			{
				/* just the named tables */
				ListCell   *l;

				foreach(l, pstate->p_locking_clause->lockedRels)
				{
					char	   *rname = strVal(lfirst(l));

					if (strcmp(refname, rname) == 0)
						return true;
				}
			}
		}
		pstate = pstate->parentParseState;
	}
	return false;
}

/*
 * Add the given RTE as a top-level entry in the pstate's join list
 * and/or name space lists.  (We assume caller has checked for any
 * namespace conflicts.)
 */
void
addRTEtoQuery(ParseState *pstate, RangeTblEntry *rte,
			  bool addToJoinList,
			  bool addToRelNameSpace, bool addToVarNameSpace)
{
	if (addToJoinList)
	{
		int			rtindex = RTERangeTablePosn(pstate, rte, NULL);
		RangeTblRef *rtr = makeNode(RangeTblRef);

		rtr->rtindex = rtindex;
		pstate->p_joinlist = lappend(pstate->p_joinlist, rtr);
	}
	if (addToRelNameSpace)
		pstate->p_relnamespace = lappend(pstate->p_relnamespace, rte);
	if (addToVarNameSpace)
		pstate->p_varnamespace = lappend(pstate->p_varnamespace, rte);
}

/*
 * Add a POSTQUEL-style implicit RTE.
 *
 * We assume caller has already checked that there is no RTE or join with
 * a conflicting name.
 */
RangeTblEntry *
addImplicitRTE(ParseState *pstate, RangeVar *relation)
{
	RangeTblEntry *rte;

	/* issue warning or error as needed */
	warnAutoRange(pstate, relation);
	/*
	 * Note that we set inFromCl true, so that the RTE will be listed
	 * explicitly if the parsetree is ever decompiled by ruleutils.c. This
	 * provides a migration path for views/rules that were originally written
	 * with implicit-RTE syntax.
	 */
	rte = addRangeTableEntry(pstate, relation, NULL, false, true);
	/* Add to joinlist and relnamespace, but not varnamespace */
	addRTEtoQuery(pstate, rte, true, true, false);

	return rte;
}

/*
 * expandRTE -- expand the columns of a rangetable entry
 *
 * This creates lists of an RTE's column names (aliases if provided, else
 * real names) and Vars for each column.  Only user columns are considered.
 * If include_dropped is FALSE then dropped columns are omitted from the
 * results.  If include_dropped is TRUE then empty strings and NULL constants
 * (not Vars!) are returned for dropped columns.
 *
 * rtindex and sublevels_up are the varno and varlevelsup values to use
 * in the created Vars.  Ordinarily rtindex should match the actual position
 * of the RTE in its rangetable.
 *
 * The output lists go into *colnames and *colvars.
 * If only one of the two kinds of output list is needed, pass NULL for the
 * output pointer for the unwanted one.
 */
void
expandRTE(RangeTblEntry *rte, int rtindex, int sublevels_up,
		  bool include_dropped,
		  List **colnames, List **colvars)
{
	int			varattno;

	if (colnames)
		*colnames = NIL;
	if (colvars)
		*colvars = NIL;

	switch (rte->rtekind)
	{
		case RTE_RELATION:
			/* Ordinary relation RTE */
			expandRelation(rte->relid, rte->eref, rtindex, sublevels_up,
						   include_dropped, colnames, colvars);
			break;
		case RTE_SUBQUERY:
			{
				/* Subquery RTE */
				ListCell   *aliasp_item = list_head(rte->eref->colnames);
				ListCell   *tlistitem;

				varattno = 0;
				foreach(tlistitem, rte->subquery->targetList)
				{
					TargetEntry *te = (TargetEntry *) lfirst(tlistitem);

					if (te->resjunk)
						continue;
					varattno++;
					Assert(varattno == te->resno);

					if (colnames)
					{
						/* Assume there is one alias per target item */
						char	   *label = strVal(lfirst(aliasp_item));

						*colnames = lappend(*colnames, makeString(pstrdup(label)));
						aliasp_item = lnext(aliasp_item);
					}

					if (colvars)
					{
						Var		   *varnode;

						varnode = makeVar(rtindex, varattno,
										  exprType((Node *) te->expr),
										  exprTypmod((Node *) te->expr),
										  sublevels_up);

						*colvars = lappend(*colvars, varnode);
					}
				}
			}
			break;
		case RTE_FUNCTION:
			{
				/* Function RTE */
				TypeFuncClass functypclass;
				Oid			funcrettype;
				TupleDesc	tupdesc;

				functypclass = get_expr_result_type(rte->funcexpr,
													&funcrettype,
													&tupdesc);
				if (functypclass == TYPEFUNC_COMPOSITE)
				{
					/* Composite data type, e.g. a table's row type */
					Assert(tupdesc);
					expandTupleDesc(tupdesc, rte->eref, rtindex, sublevels_up,
									include_dropped, colnames, colvars);
				}
				else if (functypclass == TYPEFUNC_SCALAR)
				{
					/* Base data type, i.e. scalar */
					if (colnames)
						*colnames = lappend(*colnames,
											linitial(rte->eref->colnames));

					if (colvars)
					{
						Var		   *varnode;

						varnode = makeVar(rtindex, 1,
										  funcrettype, -1,
										  sublevels_up);

						*colvars = lappend(*colvars, varnode);
					}
				}
				else if (functypclass == TYPEFUNC_RECORD)
				{
					List	   *coldeflist = rte->coldeflist;
					ListCell   *col;
					int			attnum = 0;

					foreach(col, coldeflist)
					{
						ColumnDef  *colDef = lfirst(col);

						attnum++;
						if (colnames)
						{
							char	   *attrname;

							attrname = pstrdup(colDef->colname);
							*colnames = lappend(*colnames, makeString(attrname));
						}

						if (colvars)
						{
							Var		   *varnode;
							Oid			atttypid;

							atttypid = typenameTypeId(colDef->typename);

							varnode = makeVar(rtindex,
											  attnum,
											  atttypid,
											  colDef->typename->typmod,
											  sublevels_up);

							*colvars = lappend(*colvars, varnode);
						}
					}
				}
				else
				{
					/* addRangeTableEntryForFunction should've caught this */
					elog(ERROR, "function in FROM has unsupported return type");
				}
			}
			break;
		case RTE_JOIN:
			{
				/* Join RTE */
				ListCell   *colname;
				ListCell   *aliasvar;

				Assert(list_length(rte->eref->colnames) == list_length(rte->joinaliasvars));

				varattno = 0;
				forboth(colname, rte->eref->colnames, aliasvar, rte->joinaliasvars)
				{
					Node	   *avar = (Node *) lfirst(aliasvar);

					varattno++;

					/*
					 * During ordinary parsing, there will never be any
					 * deleted columns in the join; but we have to check since
					 * this routine is also used by the rewriter, and joins
					 * found in stored rules might have join columns for
					 * since-deleted columns.  This will be signaled by a NULL
					 * Const in the alias-vars list.
					 */
					if (IsA(avar, Const))
					{
						if (include_dropped)
						{
							if (colnames)
								*colnames = lappend(*colnames,
													makeString(pstrdup("")));
							if (colvars)
								*colvars = lappend(*colvars,
												   copyObject(avar));
						}
						continue;
					}

					if (colnames)
					{
						char	   *label = strVal(lfirst(colname));

						*colnames = lappend(*colnames,
											makeString(pstrdup(label)));
					}

					if (colvars)
					{
						Var		   *varnode;

						varnode = makeVar(rtindex, varattno,
										  exprType(avar),
										  exprTypmod(avar),
										  sublevels_up);

						*colvars = lappend(*colvars, varnode);
					}
				}
			}
			break;
		default:
			elog(ERROR, "unrecognized RTE kind: %d", (int) rte->rtekind);
	}
}

/*
 * expandRelation -- expandRTE subroutine
 */
static void
expandRelation(Oid relid, Alias *eref, int rtindex, int sublevels_up,
			   bool include_dropped,
			   List **colnames, List **colvars)
{
	Relation	rel;

	/* Get the tupledesc and turn it over to expandTupleDesc */
	rel = relation_open(relid, AccessShareLock);
	expandTupleDesc(rel->rd_att, eref, rtindex, sublevels_up, include_dropped,
					colnames, colvars);
	relation_close(rel, AccessShareLock);
}

/*
 * expandTupleDesc -- expandRTE subroutine
 */
static void
expandTupleDesc(TupleDesc tupdesc, Alias *eref,
				int rtindex, int sublevels_up,
				bool include_dropped,
				List **colnames, List **colvars)
{
	int			maxattrs = tupdesc->natts;
	int			numaliases = list_length(eref->colnames);
	int			varattno;

	for (varattno = 0; varattno < maxattrs; varattno++)
	{
		Form_pg_attribute attr = tupdesc->attrs[varattno];

		if (attr->attisdropped)
		{
			if (include_dropped)
			{
				if (colnames)
					*colnames = lappend(*colnames, makeString(pstrdup("")));
				if (colvars)
				{
					/*
					 * can't use atttypid here, but it doesn't really matter
					 * what type the Const claims to be.
					 */
					*colvars = lappend(*colvars, makeNullConst(INT4OID));
				}
			}
			continue;
		}

		if (colnames)
		{
			char	   *label;

			if (varattno < numaliases)
				label = strVal(list_nth(eref->colnames, varattno));
			else
				label = NameStr(attr->attname);
			*colnames = lappend(*colnames, makeString(pstrdup(label)));
		}

		if (colvars)
		{
			Var		   *varnode;

			varnode = makeVar(rtindex, attr->attnum,
							  attr->atttypid, attr->atttypmod,
							  sublevels_up);

			*colvars = lappend(*colvars, varnode);
		}
	}
}

/*
 * expandRelAttrs -
 *	  Workhorse for "*" expansion: produce a list of targetentries
 *	  for the attributes of the rte
 *
 * As with expandRTE, rtindex/sublevels_up determine the varno/varlevelsup
 * fields of the Vars produced.  pstate->p_next_resno determines the resnos
 * assigned to the TLEs.
 */
List *
expandRelAttrs(ParseState *pstate, RangeTblEntry *rte,
			   int rtindex, int sublevels_up)
{
	List	   *names,
			   *vars;
	ListCell   *name,
			   *var;
	List	   *te_list = NIL;

	expandRTE(rte, rtindex, sublevels_up, false,
			  &names, &vars);

	forboth(name, names, var, vars)
	{
		char	   *label = strVal(lfirst(name));
		Node	   *varnode = (Node *) lfirst(var);
		TargetEntry *te;

		te = makeTargetEntry((Expr *) varnode,
							 (AttrNumber) pstate->p_next_resno++,
							 label,
							 false);
		te_list = lappend(te_list, te);
	}

	Assert(name == NULL && var == NULL);		/* lists not the same length? */

	return te_list;
}

/*
 * get_rte_attribute_name
 *		Get an attribute name from a RangeTblEntry
 *
 * This is unlike get_attname() because we use aliases if available.
 * In particular, it will work on an RTE for a subselect or join, whereas
 * get_attname() only works on real relations.