database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-03 20:02:46 +03:00
Code Activity

Promote row expressions to full-fledged citizens of the expression syntax,

Browse Source 
rather than allowing them only in a few special cases as before.  In
particular you can now pass a ROW() construct to a function that accepts
a rowtype parameter.  Internal generation of RowExprs fixes a number of
corner cases that used to not work very well, such as referencing the
whole-row result of a JOIN or subquery.  This represents a further step in
the work I started a month or so back to make rowtype values into
first-class citizens.
This commit is contained in:
Tom Lane
2004-05-10 22:44:49 +00:00
parent 9a939886ac
commit 2f63232d30
34 changed files with 1281 additions and 551 deletions
Download Patch File Download Diff File Expand all files Collapse all files

53
src/backend/optimizer/util/var.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/util/var.c,v 1.55 2003/11/29 19:51:51 pgsql Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/util/var.c,v 1.56 2004/05/10 22:44:45 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -191,19 +191,6 @@ contain_var_reference_walker(Node *node,
}
/*
* contain_whole_tuple_var
*
* Detect whether a parsetree contains any references to the whole
* tuple of a given rtable entry (ie, a Var with varattno = 0).
*/
bool
contain_whole_tuple_var(Node *node, int varno, int levelsup)
{
return contain_var_reference(node, varno, InvalidAttrNumber, levelsup);
}
/*
* contain_var_clause
* Recursively scan a clause to discover whether it contains any Var nodes
@ -486,7 +473,10 @@ pull_var_clause_walker(Node *node, pull_var_clause_context *context)
* flatten_join_alias_vars
* Replace Vars that reference JOIN outputs with references to the original
* relation variables instead. This allows quals involving such vars to be
* pushed down.
* pushed down. Whole-row Vars that reference JOIN relations are expanded
* into RowExpr constructs that name the individual output Vars. This
* is necessary since we will not scan the JOIN as a base relation, which
* is the only way that the executor can directly handle whole-row Vars.
*
* NOTE: this is used on not-yet-planned expressions. We do not expect it
* to be applied directly to a Query node.
@ -520,8 +510,39 @@ flatten_join_alias_vars_mutator(Node *node,
rte = rt_fetch(var->varno, context->root->rtable);
if (rte->rtekind != RTE_JOIN)
return node;
if (var->varattno == InvalidAttrNumber)
{
/* Must expand whole-row reference */
RowExpr *rowexpr;
List *fields = NIL;
List *l;
foreach(l, rte->joinaliasvars)
{
newvar = (Node *) lfirst(l);
/*
* If we are expanding an alias carried down from an upper
* query, must adjust its varlevelsup fields.
*/
if (context->sublevels_up != 0)
{
newvar = copyObject(newvar);
IncrementVarSublevelsUp(newvar, context->sublevels_up, 0);
}
/* Recurse in case join input is itself a join */
newvar = flatten_join_alias_vars_mutator(newvar, context);
fields = lappend(fields, newvar);
}
rowexpr = makeNode(RowExpr);
rowexpr->args = fields;
rowexpr->row_typeid = var->vartype;
rowexpr->row_format = COERCE_IMPLICIT_CAST;
return (Node *) rowexpr;
}
/* Expand join alias reference */
Assert(var->varattno > 0);
/* Okay, must expand it */
newvar = (Node *) nth(var->varattno - 1, rte->joinaliasvars);
/*