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Tweak grammar to use FastAppend rather than lappend when constructing 

expr_lists.  This appears to be the only remaining O(N^2) bottleneck
in processing many-way 'x IN (a,b,c,...)' conditions.
This commit is contained in:
Tom Lane 2003-08-22 20:34:33 +00:00
parent 92ee2528d8
commit 29a43f398a
2 changed files with 21 additions and 4 deletions
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17
src/backend/parser/gram.y
View File

@ -11,7 +11,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.429 2003/08/17 19:58:05 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.430 2003/08/22 20:34:33 tgl Exp $
*
* HISTORY
* AUTHOR DATE MAJOR EVENT
@ -108,6 +108,7 @@ static void doNegateFloat(Value *v);
DropBehavior dbehavior;
OnCommitAction oncommit;
List *list;
FastList fastlist;
Node *node;
Value *value;
ColumnRef *columnref;
@ -6719,8 +6720,18 @@ opt_indirection:
{ $$ = NIL; }
;
expr_list: a_expr { $$ = makeList1($1); }
| expr_list ',' a_expr { $$ = lappend($1, $3); }
expr_list: a_expr
{
FastList *dst = (FastList *) &$$;
makeFastList1(dst, $1);
}
| expr_list ',' a_expr
{
FastList *dst = (FastList *) &$$;
FastList *src = (FastList *) &$1;
*dst = *src;
FastAppend(dst, $3);
}
;
extract_list:

8
src/include/nodes/pg_list.h
View File

@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: pg_list.h,v 1.40 2003/08/08 21:42:48 momjian Exp $
* $Id: pg_list.h,v 1.41 2003/08/22 20:34:33 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -132,6 +132,9 @@ typedef struct List
* FastList is an optimization for building large lists. The conventional
* way to build a list is repeated lappend() operations, but that is O(N^2)
* in the number of list items, which gets tedious for large lists.
*
* Note: there are some hacks in gram.y that rely on the head pointer (the
* value-as-list) being the first field.
*/
typedef struct FastList
{
@ -144,6 +147,9 @@ typedef struct FastList
( (fl)->head = (l), (fl)->tail = llastnode((fl)->head) )
#define FastListValue(fl) ( (fl)->head )
#define makeFastList1(fl, x1) \
( (fl)->head = (fl)->tail = makeList1(x1) )
/*
* function prototypes in nodes/list.c