Get rid of our dependency on type "long" for memory size calculations.

Consistently use "Size" (or size_t, or in some places int64 or double)
as the type for variables holding memory allocation sizes.  In most
places variables' data types were fine already, but we had an ancient
habit of computing bytes from kilobytes-units GUCs with code like
"work_mem * 1024L".  That risks overflow on Win64 where they did not
make "long" as wide as "size_t".  We worked around that by restricting
such GUCs' ranges, so you couldn't set work_mem et al higher than 2GB
on Win64.  This patch removes that restriction, after replacing such
calculations with "work_mem * (Size) 1024" or variants of that.

It should be noted that this patch was constructed by searching
outwards from the GUCs that have MAX_KILOBYTES as upper limit.
So I can't positively guarantee there are no other places doing
memory-size arithmetic in int or long variables.  I do however feel
pretty confident that increasing MAX_KILOBYTES on Win64 is safe now.
Also, nothing in our code should be dealing in multiple-gigabyte
allocations without authorization from a relevant GUC, so it seems
pretty likely that this search caught everything that could be at
risk of overflow.

Author: Vladlen Popolitov <v.popolitov@postgrespro.ru>
Co-authored-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/1a01f0-66ec2d80-3b-68487680@27595217

2 files changed, 8 insertions, 8 deletions

diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
index ec004ed9493..73d78617009 100644
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -1903,7 +1903,7 @@ cost_tuplesort(Cost *startup_cost, Cost *run_cost,
 	double		input_bytes = relation_byte_size(tuples, width);
 	double		output_bytes;
 	double		output_tuples;
-	long		sort_mem_bytes = sort_mem * 1024L;
+	int64		sort_mem_bytes = sort_mem * (int64) 1024;
 
 	/*
 	 * We want to be sure the cost of a sort is never estimated as zero, even
@@ -2488,7 +2488,7 @@ cost_material(Path *path,
 	Cost		startup_cost = input_startup_cost;
 	Cost		run_cost = input_total_cost - input_startup_cost;
 	double		nbytes = relation_byte_size(tuples, width);
-	long		work_mem_bytes = work_mem * 1024L;
+	double		work_mem_bytes = work_mem * (Size) 1024;
 
 	path->rows = tuples;
 
@@ -4028,7 +4028,7 @@ final_cost_mergejoin(PlannerInfo *root, MergePath *path,
 	else if (enable_material && innersortkeys != NIL &&
 			 relation_byte_size(inner_path_rows,
 								inner_path->pathtarget->width) >
-			 (work_mem * 1024L))
+			 work_mem * (Size) 1024)
 		path->materialize_inner = true;
 	else
 		path->materialize_inner = false;
@@ -4663,7 +4663,7 @@ cost_rescan(PlannerInfo *root, Path *path,
 				Cost		run_cost = cpu_tuple_cost * path->rows;
 				double		nbytes = relation_byte_size(path->rows,
 														path->pathtarget->width);
-				long		work_mem_bytes = work_mem * 1024L;
+				double		work_mem_bytes = work_mem * (Size) 1024;
 
 				if (nbytes > work_mem_bytes)
 				{
@@ -4690,7 +4690,7 @@ cost_rescan(PlannerInfo *root, Path *path,
 				Cost		run_cost = cpu_operator_cost * path->rows;
 				double		nbytes = relation_byte_size(path->rows,
 														path->pathtarget->width);
-				long		work_mem_bytes = work_mem * 1024L;
+				double		work_mem_bytes = work_mem * (Size) 1024;
 
 				if (nbytes > work_mem_bytes)
 				{
@@ -6496,7 +6496,7 @@ compute_bitmap_pages(PlannerInfo *root, RelOptInfo *baserel,
 	double		pages_fetched;
 	double		tuples_fetched;
 	double		heap_pages;
-	long		maxentries;
+	double		maxentries;
 
 	/*
 	 * Fetch total cost of obtaining the bitmap, as well as its total
@@ -6527,7 +6527,7 @@ compute_bitmap_pages(PlannerInfo *root, RelOptInfo *baserel,
 	 * the bitmap at one time.)
 	 */
 	heap_pages = Min(pages_fetched, baserel->pages);
-	maxentries = tbm_calculate_entries(work_mem * 1024L);
+	maxentries = tbm_calculate_entries(work_mem * (Size) 1024);
 
 	if (loop_count > 1)
 	{
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 8a474a50be7..ffd7517ea97 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -6887,7 +6887,7 @@ plan_create_index_workers(Oid tableOid, Oid indexOid)
 	 * parallel worker to sort.
 	 */
 	while (parallel_workers > 0 &&
-		   maintenance_work_mem / (parallel_workers + 1) < 32768L)
+		   maintenance_work_mem / (parallel_workers + 1) < 32 * 1024)
 		parallel_workers--;
 
 done: