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Add CREATE RECURSIVE VIEW syntax

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This is specified in the SQL standard.  The CREATE RECURSIVE VIEW
specification is transformed into a normal CREATE VIEW statement with a
WITH RECURSIVE clause.

reviewed by Abhijit Menon-Sen and Stephen Frost
This commit is contained in:
Peter Eisentraut
2013-01-31 22:31:58 -05:00
parent b1980f6d03
commit 5839052693
4 changed files with 158 additions and 1 deletions
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85
src/backend/parser/gram.y
View File

@ -164,6 +164,7 @@ static void SplitColQualList(List *qualList,
static void processCASbits(int cas_bits, int location, const char *constrType,
bool *deferrable, bool *initdeferred, bool *not_valid,
bool *no_inherit, core_yyscan_t yyscanner);
static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
%}
@ -7839,6 +7840,30 @@ ViewStmt: CREATE OptTemp VIEW qualified_name opt_column_list opt_reloptions
n->options = $8;
$$ = (Node *) n;
}
| CREATE OptTemp RECURSIVE VIEW qualified_name '(' columnList ')' opt_reloptions
AS SelectStmt
{
ViewStmt *n = makeNode(ViewStmt);
n->view = $5;
n->view->relpersistence = $2;
n->aliases = $7;
n->query = makeRecursiveViewSelect(n->view->relname, n->aliases, $11);
n->replace = false;
n->options = $9;
$$ = (Node *) n;
}
| CREATE OR REPLACE OptTemp RECURSIVE VIEW qualified_name '(' columnList ')' opt_reloptions
AS SelectStmt
{
ViewStmt *n = makeNode(ViewStmt);
n->view = $7;
n->view->relpersistence = $4;
n->aliases = $9;
n->query = makeRecursiveViewSelect(n->view->relname, n->aliases, $13);
n->replace = true;
n->options = $11;
$$ = (Node *) n;
}
;
opt_check_option:
@ -13570,6 +13595,66 @@ processCASbits(int cas_bits, int location, const char *constrType,
}
}
/*----------
* Recursive view transformation
*
* Convert
*
* CREATE RECURSIVE VIEW relname (aliases) AS query
*
* to
*
* CREATE VIEW relname (aliases) AS
* WITH RECURSIVE relname (aliases) AS (query)
* SELECT aliases FROM relname
*
* Actually, just the WITH ... part, which is then inserted into the original
* view definition as the query.
* ----------
*/
static Node *
makeRecursiveViewSelect(char *relname, List *aliases, Node *query)
{
SelectStmt *s = makeNode(SelectStmt);
WithClause *w = makeNode(WithClause);
CommonTableExpr *cte = makeNode(CommonTableExpr);
List *tl = NIL;
ListCell *lc;
/* create common table expression */
cte->ctename = relname;
cte->aliascolnames = aliases;
cte->ctequery = query;
cte->location = -1;
/* create WITH clause and attach CTE */
w->recursive = true;
w->ctes = list_make1(cte);
w->location = -1;
/* create target list for the new SELECT from the alias list of the
* recursive view specification */
foreach (lc, aliases)
{
ResTarget *rt = makeNode(ResTarget);
rt->name = NULL;
rt->indirection = NIL;
rt->val = makeColumnRef(strVal(lfirst(lc)), NIL, -1, 0);
rt->location = -1;
tl = lappend(tl, rt);
}
/* create new SELECT combining WITH clause, target list, and fake FROM
* clause */
s->withClause = w;
s->targetList = tl;
s->fromClause = list_make1(makeRangeVar(NULL, relname, -1));
return (Node *) s;
}
/* parser_init()
* Initialize to parse one query string
*/