* Use SQLite 3.7.0's write-ahead logging (WAL mode). This is a lot

  faster than the old mode when fsyncs are enabled, because it only
  performs an fsync() when doing a checkpoint, rather than at every
  commit.  Some timings for doing a "nix-instantiate /etc/nixos/nixos
  -A system" after modifying the stdenv setup script:

    42.5s - SQLite 3.6.23 with truncate mode and fsync
     3.4s - SQLite 3.6.23 with truncate mode and no fsync
    32.1s - SQLite 3.7.0 with truncate mode and fsync
    16.8s - SQLite 3.7.0 with WAL mode and fsync, auto-checkpoint
            every 1000 pages
     8.3s - SQLite 3.7.0 with WAL mode and fsync, auto-checkpoint
            every 8192 pages
     1.7s - SQLite 3.7.0 with WAL mode and no fsync

  The default is now to use WAL mode with fsyncs.  Because WAL doesn't
  work on remote filesystems such as NFS (as it uses shared memory),
  truncate mode can be re-enabled by setting the "use-sqlite-wal"
  option to false.

1 files changed, 1 insertions, 0 deletions

diff --git a/bootstrap.sh b/bootstrap.sh
index f007c713bf54..2547f5dc88db 100755
--- a/bootstrap.sh
+++ b/bootstrap.sh
@@ -1,4 +1,5 @@
 #! /bin/sh -e
+rm -f aclocal.m4
 mkdir -p config
 libtoolize --copy
 aclocal