Change min mmap size from 1MB to 32KB.

This commit adjusts the minimum mmap size from 1MB to 32KB. The
previous limit was arbitrary and causes wasted space for very small
databases.

Thanks to @mcuadros for submitting the original pull request:

  https://github.com/boltdb/bolt/pull/351

1 files changed, 2 insertions, 2 deletions

diff --git a/db.go b/db.go
index b78640f..5b905be 100644
--- a/db.go
+++ b/db.go
@@ -256,8 +256,8 @@ func (db *DB) munmap() error {
 // of the database. The minimum size is 1MB and doubles until it reaches 1GB.
 // Returns an error if the new mmap size is greater than the max allowed.
 func (db *DB) mmapSize(size int) (int, error) {
-	// Double the size from 1MB until 1GB.
-	for i := uint(20); i <= 30; i++ {
+	// Double the size from 32KB until 1GB.
+	for i := uint(15); i <= 30; i++ {
 		if size <= 1<<i {
 			return 1 << i, nil
 		}