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

Reimplement the linked list data structure used throughout the backend.

Browse Source 
In the past, we used a 'Lispy' linked list implementation: a "list" was
merely a pointer to the head node of the list. The problem with that
design is that it makes lappend() and length() linear time. This patch
fixes that problem (and others) by maintaining a count of the list
length and a pointer to the tail node along with each head node pointer.
A "list" is now a pointer to a structure containing some meta-data
about the list; the head and tail pointers in that structure refer
to ListCell structures that maintain the actual linked list of nodes.

The function names of the list API have also been changed to, I hope,
be more logically consistent. By default, the old function names are
still available; they will be disabled-by-default once the rest of
the tree has been updated to use the new API names.
This commit is contained in:
Neil Conway
2004-05-26 04:41:50 +00:00
parent 18d0d10563
commit d0b4399d81
125 changed files with 3639 additions and 3038 deletions
Download Patch File Download Diff File Expand all files Collapse all files

45
src/backend/optimizer/util/pathnode.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/util/pathnode.c,v 1.104 2004/04/25 18:23:56 neilc Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/util/pathnode.c,v 1.105 2004/05/26 04:41:27 neilc Exp $
*
*-------------------------------------------------------------------------
*/
@ -200,7 +200,7 @@ void
set_cheapest(RelOptInfo *parent_rel)
{
List *pathlist = parent_rel->pathlist;
List *p;
ListCell *p;
Path *cheapest_startup_path;
Path *cheapest_total_path;
@ -209,9 +209,9 @@ set_cheapest(RelOptInfo *parent_rel)
if (pathlist == NIL)
elog(ERROR, "could not devise a query plan for the given query");
cheapest_startup_path = cheapest_total_path = (Path *) lfirst(pathlist);
cheapest_startup_path = cheapest_total_path = (Path *) linitial(pathlist);
foreach(p, lnext(pathlist))
for_each_cell(p, lnext(list_head(pathlist)))
{
Path *path = (Path *) lfirst(p);
int cmp;
@ -269,17 +269,17 @@ add_path(RelOptInfo *parent_rel, Path *new_path)
{
bool accept_new = true; /* unless we find a superior old
* path */
List *insert_after = NIL; /* where to insert new item */
List *p1_prev = NIL;
List *p1;
ListCell *insert_after = NULL; /* where to insert new item */
ListCell *p1_prev = NULL;
ListCell *p1;
/*
* Loop to check proposed new path against old paths. Note it is
* possible for more than one old path to be tossed out because
* new_path dominates it.
*/
p1 = parent_rel->pathlist; /* cannot use foreach here */
while (p1 != NIL)
p1 = list_head(parent_rel->pathlist); /* cannot use foreach here */
while (p1 != NULL)
{
Path *old_path = (Path *) lfirst(p1);
bool remove_old = false; /* unless new proves superior */
@ -346,15 +346,14 @@ add_path(RelOptInfo *parent_rel, Path *new_path)
*/
if (remove_old)
{
List *p1_next = lnext(p1);
if (p1_prev)
lnext(p1_prev) = p1_next;
else
parent_rel->pathlist = p1_next;
parent_rel->pathlist = list_delete_cell(parent_rel->pathlist,
p1, p1_prev);
/* Delete the data pointed-to by the deleted cell */
pfree(old_path);
pfree(p1); /* this is why we can't use foreach */
p1 = p1_next;
if (p1_prev)
p1 = lnext(p1_prev);
else
p1 = list_head(parent_rel->pathlist);
}
else
{
@ -378,7 +377,7 @@ add_path(RelOptInfo *parent_rel, Path *new_path)
{
/* Accept the new path: insert it at proper place in pathlist */
if (insert_after)
lnext(insert_after) = lcons(new_path, lnext(insert_after));
lappend_cell(parent_rel->pathlist, insert_after, new_path);
else
parent_rel->pathlist = lcons(new_path, parent_rel->pathlist);
}
@ -508,7 +507,7 @@ AppendPath *
create_append_path(RelOptInfo *rel, List *subpaths)
{
AppendPath *pathnode = makeNode(AppendPath);
List *l;
ListCell *l;
pathnode->path.pathtype = T_Append;
pathnode->path.parent = rel;
@ -522,7 +521,7 @@ create_append_path(RelOptInfo *rel, List *subpaths)
{
Path *subpath = (Path *) lfirst(l);
if (l == subpaths) /* first node? */
if (l == list_head(subpaths)) /* first node? */
pathnode->path.startup_cost = subpath->startup_cost;
pathnode->path.total_cost += subpath->total_cost;
}
@ -608,7 +607,7 @@ create_unique_path(Query *root, RelOptInfo *rel, Path *subpath)
Path agg_path; /* dummy for result of cost_agg */
MemoryContext oldcontext;
List *sub_targetlist;
List *l;
ListCell *l;
int numCols;
/* Caller made a mistake if subpath isn't cheapest_total */
@ -783,7 +782,7 @@ is_distinct_query(Query *query)
*/
if (query->groupClause)
{
List *gl;
ListCell *gl;
foreach(gl, query->groupClause)
{
@ -818,7 +817,7 @@ is_distinct_query(Query *query)
static bool
hash_safe_tlist(List *tlist)
{
List *tl;
ListCell *tl;
foreach(tl, tlist)
{