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Tweak grammar to use FastAppend rather than lappend when constructing

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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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8
src/include/nodes/pg_list.h
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@@ -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