Add a fast extension-only build target and BUILDING.md

BUILDING.md

@@ -0,0 +1,73 @@
+# Building MobilityDuck
+
+MobilityDuck is a DuckDB extension. One CMake project builds DuckDB itself
+(~1300 source files), the bundled `spatial` and `icu` extensions, and
+MobilityDuck (~36 source files). The MEOS, GEOS, PROJ, GDAL and GSL
+dependencies are built by vcpkg and cached.
+
+## One-time full build
+
+```bash
+make            # release into build/release (use GEN=ninja for Ninja)
+make debug      # debug into build/debug
+```
+
+The first run compiles DuckDB and the vcpkg dependencies from source and is the
+slow one. The result is `build/release/extension/mobilityduck/mobilityduck.duckdb_extension`
+and a `build/release/duckdb` shell with the extension linked in.
+
+## Fast iteration on MobilityDuck
+
+After the one-time build, rebuild only the extension:
+
+```bash
+make ext          # rebuild build/release extension only
+make ext_debug    # rebuild build/debug extension only
+```
+
+`make ext` recompiles only the changed MobilityDuck translation units and
+relinks the `.duckdb_extension`. DuckDB, `spatial`, `icu`, `parquet` and the
+vcpkg packages are not recompiled, because they are unchanged in the build tree.
+
+Two settings cut the per-change cost further and apply automatically:
+
+- A precompiled header (`src/include/mobilityduck_pch.hpp`) parses the heavy
+  DuckDB and MEOS headers once instead of in every translation unit.
+- When `mold` is installed it is used to link the extension; the relink
+  dominates a single-file change and mold is much faster than the default
+  linker (`apt install mold`, or the equivalent for your platform). The build
+  falls back to the default linker when mold is absent.
+
+Keep the build tree in sync with the checked-out branch: switching branches (or
+building a different worktree) against a tree configured for another state makes
+CMake detect changed headers and recompile broadly. A persistent, path-independent
+`ccache` keeps those recompiles cheap (see below).
+
+## ccache across branches and worktrees
+
+`ccache` caches compiled objects. Making it path-independent lets a fresh
+worktree or a branch switch reuse DuckDB's unchanged objects instead of
+recompiling them:
+
+```bash
+export CCACHE_DIR="$HOME/.ccache"
+export CCACHE_BASEDIR="$PWD"
+ccache -M 30G
+ccache -o hash_dir=false -o sloppiness=locale,time_macros
+```
+
+## vcpkg dependency cache
+
+vcpkg stores built packages in `~/.cache/vcpkg/archives` and reuses them across
+clean build trees. MEOS, GEOS, PROJ and GDAL are rebuilt only when their version
+or the MEOS pin in `vcpkg_ports/meos/portfile.cmake` changes — ordinary
+MobilityDuck edits reuse the cache.
+
+## Installing without building
+
+End users do not build the extension. They install the distributed binary:
+
+```sql
+INSTALL mobilityduck FROM '<extension-repository>';
+LOAD mobilityduck;
+```

CMakeLists.txt

@@ -135,6 +135,25 @@ target_link_libraries(${LOADABLE_EXTENSION_NAME}
   OpenSSL::Crypto
 )
 
+# -----------------------------
+# Developer build speed
+# -----------------------------
+# Parse the heavy, stable DuckDB and MEOS headers once per build instead of in
+# every translation unit.
+target_precompile_headers(${EXTENSION_NAME} PRIVATE
+  "${CMAKE_CURRENT_SOURCE_DIR}/src/include/mobilityduck_pch.hpp")
+target_precompile_headers(${LOADABLE_EXTENSION_NAME} PRIVATE
+  "${CMAKE_CURRENT_SOURCE_DIR}/src/include/mobilityduck_pch.hpp")
+
+# Link the extension with mold when it is installed: relinking the extension
+# dominates the cost of a single-file change, and mold relinks far faster than
+# the default linker. Falls back to the default linker when mold is absent.
+find_program(MOLD_LINKER mold)
+if(MOLD_LINKER)
+  target_link_options(${EXTENSION_NAME} PRIVATE -fuse-ld=mold)
+  target_link_options(${LOADABLE_EXTENSION_NAME} PRIVATE -fuse-ld=mold)
+endif()
+
 # -----------------------------
 # Install (static & loadable)
 # -----------------------------

Makefile

@@ -51,4 +51,16 @@ test_debug_internal:
 	./build/debug/$(TEST_PATH) "$(PROJ_DIR)test/*"
 test_reldebug_internal:
 	$(call stage_icu,reldebug)
-	./build/reldebug/$(TEST_PATH) "$(PROJ_DIR)test/*"
+	./build/reldebug/$(TEST_PATH) "$(PROJ_DIR)test/*"
+
+# Fast developer iteration: rebuild ONLY the MobilityDuck extension against the
+# already-configured DuckDB build and vcpkg dependencies.  Run a full `make`
+# (release) / `make debug` once; thereafter `make ext` / `make ext_debug`
+# recompiles just the changed MobilityDuck translation units and relinks
+# build/<config>/extension/mobilityduck/mobilityduck.duckdb_extension without
+# rebuilding DuckDB, spatial, icu, parquet or the vcpkg packages.  See BUILDING.md.
+.PHONY: ext ext_debug
+ext:
+	cmake --build build/release --target mobilityduck_loadable_extension --parallel
+ext_debug:
+	cmake --build build/debug --target mobilityduck_loadable_extension --parallel

src/include/mobilityduck_pch.hpp

@@ -0,0 +1,17 @@
+// Precompiled header: the heavy, stable third-party headers shared by every
+// MobilityDuck translation unit. Compiling these once per build instead of in
+// each translation unit cuts incremental compile time. Only third-party
+// headers belong here — adding a MobilityDuck header would rebuild the whole
+// precompiled header whenever that header changes.
+#pragma once
+
+extern "C" {
+#include <meos.h>
+#include <meos_internal.h>
+}
+
+#include "duckdb/common/exception.hpp"
+#include "duckdb/common/string_util.hpp"
+#include "duckdb/function/scalar_function.hpp"
+#include "duckdb/main/extension/extension_loader.hpp"
+#include "duckdb/parser/parsed_data/create_scalar_function_info.hpp"

vcpkg_ports/meos/portfile.cmake

@@ -1,8 +1,8 @@
 vcpkg_from_github(
     OUT_SOURCE_PATH SOURCE_PATH
     REPO estebanzimanyi/MobilityDB
-    REF a8178dc9d56d841d0eb5025a7e8717c8d25a1d0f
-    SHA512 030a144bb3247695702dd2de11f4c389ed28c6eb0186e6988a489e2b00e9801179ba8f27bcbcd81ae89e398a7277ed7f9ff7058dbf15f5db322ae4644365c560
+    REF 3db47f887c61f049a6a03db55c48bedf6d10eee4
+    SHA512 b73123bca036813c43937f90f0d0ce45af5cb9e39d6a597304199d21ae854212319a3a7b58ecd075eb5678d89d6d5990b9faf63dd29bd8c9a4e2ed83282b94c5
 )
 
 vcpkg_replace_string(