add mapsize option

2 files changed, 12 insertions, 0 deletions

diff --git a/README.md b/README.md
index b4db243..7f4aa46 100644
--- a/README.md
+++ b/README.md
@@ -11,6 +11,7 @@ create a new environment handle and open the database at the `path`. returns the
 `opt` is an optional table of options:
 
 * `maxdbs`: number: the maximum number of databases in the environment. must be set if multiple databases will be used.
+* `mapsize`: number: the memory map size used for this environment. this is also the maximum size of the database. default: 1GiB (`1024^3`).
 * `rdonly`: boolean: open the environment in read-only mode.
 * `nosubdir`: boolean: the `path` is used for the database file itself and not its containing directory.
 * `nosync`: boolean: don't flush buffers to disk when committing.
diff --git a/lmdb.c b/lmdb.c
index a1c4e8e..6a6e7ba 100644
--- a/lmdb.c
+++ b/lmdb.c
@@ -70,6 +70,8 @@ static int env_open(lua_State *L) {
 	int flags = 0;
 	int maxdbs = 0;
 	int maxdbs_supplied = 0;
+	int mapsize = 0;
+	int mapsize_supplied = 0;
 	if (!lua_isnil(L, 2)) {
 		for (int i = 0; env_flags[i].name != NULL; i++) {
 			lua_getfield(L, 2, env_flags[i].name);
@@ -78,11 +80,20 @@ static int env_open(lua_State *L) {
 		}
 		lua_getfield(L, 2, "maxdbs");
 		maxdbs = lua_tointegerx(L, -1, &maxdbs_supplied);
+		lua_getfield(L, 2, "mapsize");
+		mapsize = lua_tointegerx(L, -1, &mapsize_supplied);
 	}
 
 	MDB_env *env;
 	reterr(mdb_env_create(&env));
 	if (maxdbs_supplied) mdb_env_set_maxdbs(env, maxdbs);
+	if (mapsize_supplied)
+		mdb_env_set_mapsize(env, mapsize);
+	else
+		// lmdb default mapsize is 1MiB which is tiny
+		// so we use a default of 1GiB instead
+		mdb_env_set_mapsize(env, 1073741824);
+
 	int result = mdb_env_open(env, lua_tostring(L, 1), flags, 0664);
 	if (result != 0) {
 		mdb_env_close(env);