[PATCH 0/2] Sparse Index: diff and blame builtins

This series is based on vd/sparse-reset. It integrates the sparse index with
git diff and git blame and includes:

 1. tests added to t1092 and p2000 to establish the baseline functionality
    of the commands
 2. repository settings to enable the sparse index

The p2000 tests demonstrate a ~30% execution time reduction for 'git diff'
and a ~75% execution time reduction for 'git diff --staged' using a sparse
index. For 'git blame', the reduction time was ~60% for a file two levels
deep and ~30% for a file three levels deep.

Test                                         before  after
----------------------------------------------------------------
2000.30: git diff (full-v3)                  0.37    0.36 -2.7%
2000.31: git diff (full-v4)                  0.36    0.35 -2.8%
2000.32: git diff (sparse-v3)                0.46    0.30 -34.8%
2000.33: git diff (sparse-v4)                0.43    0.31 -27.9%
2000.34: git diff --staged (full-v3)         0.08    0.08 +0.0%
2000.35: git diff --staged (full-v4)         0.08    0.08 +0.0%
2000.36: git diff --staged (sparse-v3)       0.17    0.04 -76.5%
2000.37: git diff --staged (sparse-v4)       0.16    0.04 -75.0%
2000.62: git blame f2/f4/a (full-v3)         0.31    0.32 +3.2%
2000.63: git blame f2/f4/a (full-v4)         0.29    0.31 +6.9%
2000.64: git blame f2/f4/a (sparse-v3)       0.55    0.23 -58.2%
2000.65: git blame f2/f4/a (sparse-v4)       0.57    0.23 -59.6%
2000.66: git blame f2/f4/f3/a (full-v3)      0.77    0.85 +10.4%
2000.67: git blame f2/f4/f3/a (full-v4)      0.78    0.81 +3.8%
2000.68: git blame f2/f4/f3/a (sparse-v3)    1.07    0.72 -32.7%
2000.99: git blame f2/f4/f3/a (sparse-v4)    1.05    0.73 -30.5%


Thanks, Lessley

Lessley Dennington (2):
  diff: enable and test the sparse index
  blame: enable and test the sparse index

 builtin/blame.c                          |  3 ++
 builtin/diff.c                           |  3 ++
 t/perf/p2000-sparse-operations.sh        |  4 ++
 t/t1092-sparse-checkout-compatibility.sh | 66 +++++++++++++++++++++---
 4 files changed, 69 insertions(+), 7 deletions(-)


base-commit: 57049e844c80d5fe1394e6d65b28705eabfd6585
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1050%2Fldennington%2Fdiff-blame-sparse-index-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1050/ldennington/diff-blame-sparse-index-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/1050
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