Cooling-stage clock sweep (batched sweep + HOT/COOL evictor + strategy removal)

.clangd

@@ -0,0 +1,43 @@
+Diagnostics:
+  MissingIncludes: None
+InlayHints:
+  Enabled: true
+  ParameterNames: true
+  DeducedTypes: true
+CompileFlags:
+  CompilationDatabase: build/       # Search build/ directory for compile_commands.json
+  Remove: [ -Werror ]
+  Add:
+  - -DDEBUG
+  - -DLOCAL
+  - -DPGDLLIMPORT=
+  - -DPIC
+  - -O2
+  - -Wall
+  - -Wcast-function-type
+  - -Wconversion
+  - -Wdeclaration-after-statement
+  - -Wendif-labels
+  - -Werror=vla
+  - -Wextra
+  - -Wfloat-equal
+  - -Wformat-security
+  - -Wimplicit-fallthrough=3
+  - -Wmissing-format-attribute
+  - -Wmissing-prototypes
+  - -Wno-format-truncation
+  - -Wno-sign-conversion
+  - -Wno-stringop-truncation
+  - -Wno-unused-const-variable
+  - -Wpointer-arith
+  - -Wshadow
+  - -Wshadow=compatible-local
+  - -fPIC
+  - -fexcess-precision=standard
+  - -fno-strict-aliasing
+  - -fvisibility=hidden
+  - -fwrapv
+  - -g
+  - -std=c11
+  - -I.
+  - -I../../../../src/include

.gdbinit

@@ -0,0 +1,156 @@
+# HOT Indexed Updates — GDB breakpoints for code review
+#
+# Usage:  gdb -x .gdbinit <postgres-binary>
+# Or from gdb:  source .gdbinit
+#
+# These breakpoints cover the major code paths introduced or modified by
+# the HOT indexed updates patch series.  They are organized by subsystem
+# to make it easy to enable/disable groups during debugging.
+#
+# Tip: to skip to a specific subsystem, disable all then enable selectively:
+#   disable breakpoints
+#   enable 1 2 3          # just the update-decision group
+
+# =========================================================================
+# 1. UPDATE DECISION — heap_update() HOT/HOT-indexed/non-HOT choice
+#    src/backend/access/heap/heapam.c
+# =========================================================================
+
+# Main entry: heap_update
+break heapam.c:3210
+
+# HOT decision block: pure HOT vs HOT indexed vs non-HOT
+# Line 4019: pure HOT (no indexed columns changed)
+# Line 4024: HOT indexed path (non-catalog, some indexed columns changed)
+# Line 4031: predict augmented tuple size
+# Line 4033: size+space check before creating augmented tuple
+break heapam.c:4019
+break heapam.c:4024
+break heapam.c:4033
+
+# Set HEAP_INDEXED_UPDATED flag on new tuple before page insertion
+break heapam.c:4101
+
+# Restore HEAP_INDEXED_UPDATED on old tuple (only if it previously had it)
+break heapam.c:4147
+
+# =========================================================================
+# 2. TUPLE CREATION — building the augmented tuple with embedded bitmap
+#    src/backend/access/heap/heapam.c
+# =========================================================================
+
+# Predict augmented tuple size (returns 0 if t_hoff would overflow)
+break heap_hot_indexed_tuple_size
+
+# Create augmented tuple with embedded modified-column bitmap
+break heap_hot_indexed_create_tuple
+
+# Serialize Bitmapset into raw bytes in tuple header
+break heap_hot_indexed_serialize_bitmap
+
+# =========================================================================
+# 3. BITMAP UTILITIES — raw bitmap operations for chain following
+#    src/backend/access/heap/heapam.c
+# =========================================================================
+
+# Compute raw bitmap byte size from natts
+break heap_hot_indexed_bitmap_raw_size
+
+# Check if tuple header has room for bitmap between null bitmap and data
+break heap_hot_indexed_has_bitmap_space
+
+# Read HOT indexed bitmap from tuple header (returns Bitmapset)
+break heap_hot_indexed_read_bitmap
+
+# Fast overlap check: does tuple's raw bitmap overlap with indexed_attrs?
+break heap_hot_indexed_bitmap_overlaps_raw
+
+# OR a tuple's raw bitmap into an accumulator buffer
+break heap_hot_indexed_bitmap_or_raw
+
+# Check if accumulated raw bitmap overlaps with indexed_attrs
+break heap_hot_indexed_accum_overlaps
+
+# Merge bitmaps from dead tuples into a target tuple on the page
+break heap_hot_indexed_merge_bitmaps_raw
+
+# Deserialize raw bytes back to Bitmapset
+break heap_hot_indexed_deserialize_bitmap
+
+# =========================================================================
+# 4. INDEX SCAN — HOT chain following with stale-entry detection
+#    src/backend/access/heap/heapam_indexscan.c
+# =========================================================================
+
+# Main HOT chain search with indexed update awareness
+break heap_hot_search_buffer
+
+# Redirect-with-data: initialize bitmap accumulator from collapsed redirect
+break heapam_indexscan.c:182
+
+# Accumulate bitmap from INDEXED_UPDATED tuple in chain
+break heapam_indexscan.c:250
+
+# Stale entry detection: accumulated bitmap overlaps this index's attrs
+break heapam_indexscan.c:297
+
+# =========================================================================
+# 5. INDEX SCAN SETUP — indexed_attrs bitmap computation
+#    src/backend/access/index/indexam.c
+# =========================================================================
+
+# Compute indexed_attrs for HOT indexed update chain following
+break indexam.c:299
+
+# =========================================================================
+# 6. INDEX INSERTION — skip unchanged indexes for HOT indexed updates
+#    src/backend/executor/execIndexing.c
+# =========================================================================
+
+# Entry: insert/update index tuples
+break ExecInsertIndexTuples
+
+# Index skip decision: skip indexes whose attrs don't overlap modified set
+break execIndexing.c:370
+
+# =========================================================================
+# 7. PRUNING — chain collapsing and redirect-with-data
+#    src/backend/access/heap/pruneheap.c
+# =========================================================================
+
+# Main prune function
+break heap_page_prune_and_freeze
+
+# Per-chain pruning entry
+break heap_prune_chain
+
+# Chain collapsing: collect bitmaps from dead INDEXED_UPDATED intermediates
+break pruneheap.c:1802
+
+# OR dead tuple bitmaps into combined bitmap
+break pruneheap.c:1836
+
+# Record redirect-with-data for execute phase
+break pruneheap.c:1863
+
+# Execute phase: apply redirect-with-data entries on the page
+break pruneheap.c:1287
+
+# =========================================================================
+# 8. WAL REPLAY — recovery of HOT indexed updates
+#    src/backend/access/heap/heapam_xlog.c
+# =========================================================================
+
+# WAL replay for XLOG_HEAP2_INDEXED_UPDATE
+break heap_xlog_indexed_update
+
+# =========================================================================
+# 9. WAL LOGGING — writing HOT indexed update records
+#    src/backend/access/heap/heapam.c
+# =========================================================================
+
+# WAL logging for heap updates (handles indexed_update flag)
+break log_heap_update
+
+# Serialize redirect-with-data into WAL record (pruneheap.c)
+break pruneheap.c:2936

contrib/pg_buffercache/pg_buffercache_pages.c

@@ -161,7 +161,7 @@ pg_buffercache_pages(PG_FUNCTION_ARGS)
 		reldatabase = bufHdr->tag.dbOid;
 		forknum = BufTagGetForkNum(&bufHdr->tag);
 		blocknum = bufHdr->tag.blockNum;
-		usagecount = BUF_STATE_GET_USAGECOUNT(buf_state);
+		usagecount = BUF_STATE_GET_COOLSTATE(buf_state);
 		pinning_backends = BUF_STATE_GET_REFCOUNT(buf_state);
 
 		if (buf_state & BM_DIRTY)
@@ -605,7 +605,7 @@ pg_buffercache_summary(PG_FUNCTION_ARGS)
 		if (buf_state & BM_VALID)
 		{
 			buffers_used++;
-			usagecount_total += BUF_STATE_GET_USAGECOUNT(buf_state);
+			usagecount_total += BUF_STATE_GET_COOLSTATE(buf_state);
 
 			if (buf_state & BM_DIRTY)
 				buffers_dirty++;
@@ -655,7 +655,7 @@ pg_buffercache_usage_counts(PG_FUNCTION_ARGS)
 
 		CHECK_FOR_INTERRUPTS();
 
-		usage_count = BUF_STATE_GET_USAGECOUNT(buf_state);
+		usage_count = BUF_STATE_GET_COOLSTATE(buf_state);
 		usage_counts[usage_count]++;
 
 		if (buf_state & BM_DIRTY)

flake.nix

@@ -0,0 +1,45 @@
+{
+  description = "PostgreSQL development environment";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-25.05";
+    nixpkgs-unstable.url = "github:nixos/nixpkgs/nixpkgs-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = {
+    self,
+    nixpkgs,
+    nixpkgs-unstable,
+    flake-utils,
+  }:
+    flake-utils.lib.eachDefaultSystem (
+      system: let
+        pkgs = import nixpkgs {
+          inherit system;
+          config.allowUnfree = true;
+        };
+        pkgs-unstable = import nixpkgs-unstable {
+          inherit system;
+          config.allowUnfree = true;
+        };
+
+        shellConfig = import ./shell.nix {inherit pkgs pkgs-unstable system;};
+      in {
+        formatter = pkgs.alejandra;
+        devShells = {
+          default = shellConfig.devShell;
+          gcc = shellConfig.devShell;
+          clang = shellConfig.clangDevShell;
+          gcc-musl = shellConfig.muslDevShell;
+          clang-musl = shellConfig.clangMuslDevShell;
+        };
+
+        packages = {
+          inherit (shellConfig) gdbConfig flameGraphScript pgbenchScript;
+        };
+
+        environment.localBinInPath = true;
+      }
+    );
+}

glibc-no-fortify-warning.patch

@@ -0,0 +1,24 @@
+From 130c231020f97e5eb878cc9fdb2bd9b186a5aa04 Mon Sep 17 00:00:00 2001
+From: Greg Burd <greg@burd.me>
+Date: Fri, 24 Oct 2025 11:58:24 -0400
+Subject: [PATCH] no warnings with -O0 and fortify source please
+
+---
+ include/features.h | 1 -
+ 1 file changed, 1 deletion(-)
+
+diff --git a/include/features.h b/include/features.h
+index 673c4036..a02c8a3f 100644
+--- a/include/features.h
++++ b/include/features.h
+@@ -432,7 +432,6 @@
+
+ #if defined _FORTIFY_SOURCE && _FORTIFY_SOURCE > 0
+ # if !defined __OPTIMIZE__ || __OPTIMIZE__ <= 0
+-#  warning _FORTIFY_SOURCE requires compiling with optimization (-O)
+ # elif !__GNUC_PREREQ (4, 1)
+ #  warning _FORTIFY_SOURCE requires GCC 4.1 or later
+ # elif _FORTIFY_SOURCE > 2 && (__glibc_clang_prereq (9, 0)		      \
+--
+2.50.1
+