思路

先用partial clone和git fetch来下载metadata，然后再用ls-tree得到文件树，最后一个文件一个文件地checkout

代码

checkout_partial.ps1

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param (
    [Parameter(Mandatory = $true)]
    [string]$RepoUrl,

    [int]$BatchSize = 1
)

# ---------- Encoding & git global-friendly settings ----------
try {
    [Console]::OutputEncoding = [System.Text.Encoding]::UTF8
    [Console]::InputEncoding  = [System.Text.Encoding]::UTF8
    $OutputEncoding = New-Object System.Text.UTF8Encoding $false
} catch {
    Write-Host "Warning: Unable to set console encoding. Continuing..."
}

# Helpful git defaults for Unicode output
git config --global core.quotepath false | Out-Null
git config --global core.precomposeUnicode true | Out-Null
git config --global i18n.logOutputEncoding utf-8 | Out-Null

# ---------- Prepare repo dir ----------
$RepoDir = [System.IO.Path]::GetFileNameWithoutExtension($RepoUrl)
Write-Host "Preparing repository: $RepoDir"

if (Test-Path $RepoDir) {
    if (Test-Path (Join-Path $RepoDir ".git")) {
        Write-Host "Found existing git repo at '$RepoDir' — reusing it (no reclone)."
        Set-Location $RepoDir
        Write-Host "Fetching remote metadata..."
        git -c core.quotepath=false -c i18n.logOutputEncoding=utf-8 fetch --all
        if ($LASTEXITCODE -ne 0) {
            Write-Host "Warning: git fetch --all returned non-zero exit code."
        }
    } else {
        Write-Host "Directory '$RepoDir' exists but is not a git repo. Aborting to avoid overwrite."
        exit 1
    }
} else {
    Write-Host "Cloning (partial) into '$RepoDir' ..."
    git -c core.quotepath=false -c i18n.logOutputEncoding=utf-8 clone --filter=blob:none --no-checkout $RepoUrl $RepoDir
    if ($LASTEXITCODE -ne 0) {
        Write-Host "Clone failed. You can try a full clone (without --filter=blob:none) as fallback."
        exit 1
    }
    Set-Location $RepoDir
    Write-Host "Fetching metadata..."
    git -c core.quotepath=false -c i18n.logOutputEncoding=utf-8 fetch --all
}

# ---------- Get file list from HEAD ----------
# Use -z to safely handle filenames including newlines and unicode
$FileListRaw = & git -c core.quotepath=false -c i18n.logOutputEncoding=utf-8 ls-tree -r --name-only -z HEAD 2>$null
if (-not $FileListRaw) {
    Write-Host "No files found in HEAD (maybe repository empty or no HEAD). Exiting."
    exit 0
}
$FileList = $FileListRaw -split "`0" | Where-Object { $_ -ne "" }

Write-Host "Total files to checkout: $($FileList.Count)"
Write-Host "Starting checkout in batches of $BatchSize ..."

# ---------- Checkout loop with skip logic ----------
for ($i = 0; $i -lt $FileList.Count; $i += $BatchSize) {
    $Batch = $FileList[$i..([Math]::Min($i + $BatchSize - 1, $FileList.Count - 1))]
    $start = $i + 1
    $end = [Math]::Min($i + $BatchSize, $FileList.Count)
    Write-Host "Batch $start - $end ..."

    $BatchToCheckout = @()
    foreach ($rel in $Batch) {
        # Ensure we test the correct file path relative to repo root
        $fullPath = Join-Path (Get-Location) $rel

        if (-not (Test-Path $fullPath)) {
            $BatchToCheckout += $rel
        } else {
            # If file exists but size == 0, re-checkout (could be placeholder)
            try {
                $length = (Get-Item $fullPath -ErrorAction Stop).Length
                if ($length -eq 0) {
                    Write-Host "  Re-checkout (empty file): $rel"
                    $BatchToCheckout += $rel
                } else {
                    Write-Host "  Skipping existing file: $rel"
                }
            } catch {
                Write-Host "  Skipping (unable to stat): $rel"
            }
        }
    }

    if ($BatchToCheckout.Count -eq 0) {
        Write-Host "  All files in this batch already present — skipping."
        continue
    }

    # Try checkout; if fails, try fetching shallow blobs and retry once
    & git -c core.quotepath=false -c i18n.logOutputEncoding=utf-8 checkout HEAD -- $BatchToCheckout
    if ($LASTEXITCODE -ne 0) {
        Write-Host "  Checkout failed for some files in this batch. Attempting conservative fetch and retry..."
        & git fetch --depth=1 origin
        & git -c core.quotepath=false -c i18n.logOutputEncoding=utf-8 checkout HEAD -- $BatchToCheckout
        if ($LASTEXITCODE -ne 0) {
            Write-Host "  Still failed on this batch. Possible causes:"
            Write-Host "    - missing blobs on server / partial-clone negotiation issue"
            Write-Host "    - repository uses Git LFS (you may see pointer files)"
            Write-Host "  These files will remain unchecked out; continuing to next batch."
        } else {
            Write-Host "  Retry succeeded for this batch."
        }
    } else {
        Write-Host "  Checkout succeeded for this batch."
    }
}


使用

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Set-ExecutionPolicy -Scope Process -ExecutionPolicy Bypass
.\checkout_partial.ps1 -RepoUrl "你的git url" -BatchSize 5