Hi Stolee
On 07/05/2025 01:55, Derrick Stolee via GitGitGadget wrote:
The sparse index helps make some Git commands faster when using
sparse-checkout in cone mode. However, not all code paths are aware that the
index can have non-blob entries, so we are careful about rolling this
feature out gradually. The cost of this rollout is that some commands are
slower with the sparse index as they need to expand a sparse index into a
full index in memory, which requires parsing tree objects to construct the
full path list.
This patch series focuses on the 'git add -p' command, which is slow with
the sparse index for a couple of reasons, handled in the first two patches:
1. 'git add -p' uses 'git apply' as a subcommand and 'git apply' needs
integration with the sparse index. Luckily, we just need to add the repo
setting and appropriate tests to confirm it behaves as expected.
2. The interactive modes of 'git add' ('-p' and '-i') leave cmd_add()
before the code that sets the repo setting to allow for a sparse index.
Patch 2 fixes this and adds appropriate tests to confirm the behavior in
a sparse-checkout.
This made me wonder about the other commands that take "--patch" like
checkout and reset. Do you know how well they handle the sparse index?
They'll all benefit from the changes to git apply in this series but I
was wondering if they need any further changes.
Best Wishes
Phillip
A third patch adds a performance test to p2000-sparse-operations.sh to
confirm that we are getting the performance improvement we expect:
BASE PATCH 1 PATCH 2
---------------------------------------------------------
2000.118: (full-v3) 0.80 0.84 +5.0% 0.84 +5.0%
2000.119: (full-v4) 0.76 0.79 +3.9% 0.80 +5.3%
2000.120: (sparse-v3) 2.09 1.39 -33.5% 0.07 -96.7%
2000.121: (sparse-v4) 2.09 1.39 -33.5% 0.07 -96.7%
Thanks, -Stolee
Derrick Stolee (3):
apply: integrate with the sparse index
git add: make -p/-i aware of sparse index
p2000: add performance test for 'git add -p'
builtin/add.c | 7 +-
builtin/apply.c | 7 +-
t/perf/p2000-sparse-operations.sh | 1 +
t/t1092-sparse-checkout-compatibility.sh | 102 +++++++++++++++++++++++
4 files changed, 113 insertions(+), 4 deletions(-)
base-commit: 6c0bd1fc70efaf053abe4e57c976afdc72d15377
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1914%2Fderrickstolee%2Fapply-sparse-index-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1914/derrickstolee/apply-sparse-index-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/1914
