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This is an automated cherry-pick of #10379

What problem does this PR solve?

Issue Number: close #10361

Problem Summary:

What is changed and how it works?

Storage: Fix TableScan performance regression under wide-sparse table
* Use merged_file_info.size as the buffer size when reading data  (mark, min-max index, col-data) from merged file to minimize read amplification
* Use merged_file_info.size as the buffer size when parsing data as ChecksumReadBuffer to minimize the memory allocation overhead
* Introduce class `MinMaxIndexLoader` to tidy codes of reading min-max index

test logging output: test.log.zip

Tested on x86_64 8c 32GB (m7i.2xlarge), with 16000 iops, 625MB/s throughput gp3 EBS (amd_rockylinux9)
Compare the uncompressed read/write throughput using the dttool bench

Before this PR:

  • the write throughput has increase by more than 60% compared to v2 format
  • the read throughput decrease about 10%~20% after using v3 DMFile format. Especially on wide-sparse table.
sparse_ratio v2 write throughput v2 read throughput v3 write throughput v3 read throughput
0 132.409 1814.432 220.047 (+66.2%) 1671.053 (-7.9%)
0.05 132.893 1695.434 216.352 (+62.8%) 1486.356 (-12.3%)
0.1 129.537 1599.987 212.952 (+64.4%) 1375.033 (-14.1%)
0.5 130.932 1318.756 211.084 (+61.2%) 1120.210 (-15.1%)
0.8 137.630 1497.458 227.778 (+65.5%) 1216.922 (-18.7%)
0.9 149.608 1737.411 245.560 (+64.1%) 1361.528 (-21.6%)
0.99 162.110 2160.127 295.130 (+82.1%) 1564.444 (-27.6%)

After this PR:

  • the write throughput has increase by more than 60% compared to v2 format
  • the read throughput change is not significant. Regression is not larger than 7%
sparse_ratio v2 write throughput v2 read throughput v3 write throughput v3 read throughput
0 131.757 1771.513 221.029 (+67.8%) 1839.603 (+3.8%)
0.05 129.977 1683.676 220.039 (+69.3%) 1691.280 (+0.5%)
0.1 130.816 1580.936 211.728 (+61.9%) 1559.970 (-1.3%)
0.5 130.103 1337.525 211.439 (+62.5%) 1292.864 (-3.3%)
0.8 140.769 1479.410 227.881 (+61.9%) 1386.370 (-6.3%)
0.9 146.884 1664.910 244.082 (+66.2%) 1603.719 (-3.7%)
0.99 161.374 2098.286 291.528 (+80.7%) 2116.858 (+0.9%)

Compare the read/write throughput of v3 DMFile format before and after this PR:

  • The write throughput is almost not changed
  • The read throughput has increased a lot, especially on the sparse-table scenario
sparse_ratio v3 (before) write throughput v3 (before) read throughput v3 (after) write throughput v3 (after) read throughput
0 220.047 1671.053 221.029 (+0.4%) 1839.603 (+10.1%)
0.05 216.352 1486.356 220.039 (+1.7%) 1691.280 (+13.8%)
0.1 212.952 1375.033 211.728 (-0.6%) 1559.970 (+13.4%)
0.5 211.084 1120.210 211.439 (+0.2%) 1292.864 (+15.4%)
0.8 227.778 1216.922 227.881 (+0.0%) 1386.370 (+13.9%)
0.9 245.560 1361.528 244.082 (-0.6%) 1603.719 (+17.8%)
0.99 295.130 1564.444 291.528 (-1.2%) 2116.858 (+35.3%)

Check List

Tests

  • Unit test
  • Integration test
  • Manual test (add detailed scripts or steps below)
#!/bin/bash

# Define arrays for sparse-ratio and version
sparse_ratios=(0 0.05 0.1 0.5 0.8 0.9 0.99)
#sparse_ratios=(0 0.1 0.9 0.99)
versions=(2 3)

# Define the base command and fixed arguments
base_cmd="beforefix/tiflash/tiflash"
sub_cmd="dttool bench"
fixed_args="--columns 600 --rows 131000 --field 12 --write-repeat 5 --repeat 20 --random 2021268696"

# Iterate through all combinations of sparse-ratio and version
for version in "${versions[@]}"; do
  for sparse_ratio in "${sparse_ratios[@]}"; do
    # Define a unique workdir for each run
    workdir="./tmp_v${version}_sr${sparse_ratio}"

    # Construct the full command
    cmd="${base_cmd} ${sub_cmd} ${fixed_args} --sparse-ratio ${sparse_ratio} --workdir ${workdir} --version ${version}"

    # Print the command being executed (optional, for logging/debugging)
    echo "Executing: $cmd"

    # Execute the command
    $cmd

    # Check if the command executed successfully
    if [ $? -ne 0 ]; then
      echo "Error: Command failed for version ${version}, sparse-ratio ${sparse_ratio}"
      # Optional: Add 'exit 1' here to stop the script on failure
      # exit 1
    fi

    echo "----------------------------------------"
  done
done

echo "All benchmarks completed."
echo "=================================="

base_cmd="afterfix/tiflash/tiflash"

# Iterate through all combinations of sparse-ratio and version
for version in "${versions[@]}"; do
  for sparse_ratio in "${sparse_ratios[@]}"; do
    # Define a unique workdir for each run
    workdir="./tmp_v${version}_sr${sparse_ratio}"

    # Construct the full command
    cmd="${base_cmd} ${sub_cmd} ${fixed_args} --sparse-ratio ${sparse_ratio} --workdir ${workdir} --version ${version}"

    # Print the command being executed (optional, for logging/debugging)
    echo "Executing: $cmd"

    # Execute the command
    $cmd

    # Check if the command executed successfully
    if [ $? -ne 0 ]; then
      echo "Error: Command failed for version ${version}, sparse-ratio ${sparse_ratio}"
      # Optional: Add 'exit 1' here to stop the script on failure
      # exit 1
    fi

    echo "----------------------------------------"
  done
done

echo "All benchmarks completed."
  • No code

Side effects

  • Performance regression: Consumes more CPU
  • Performance regression: Consumes more Memory
  • Breaking backward compatibility

Documentation

  • Affects user behaviors
  • Contains syntax changes
  • Contains variable changes
  • Contains experimental features
  • Changes MySQL compatibility

Release note

Fix a bug that cause TableScan performance regression under wide-sparse table

Signed-off-by: ti-chi-bot <ti-community-prow-bot@tidb.io>
@ti-chi-bot ti-chi-bot added do-not-merge/hold Indicates that a PR should not merge because someone has issued a /hold command. release-note Denotes a PR that will be considered when it comes time to generate release notes. size/XL Denotes a PR that changes 500-999 lines, ignoring generated files. type/cherry-pick-for-release-8.1 This PR is cherry-picked to release-8.1 from a source PR. labels Aug 29, 2025
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ti-chi-bot bot commented Aug 29, 2025

This cherry pick PR is for a release branch and has not yet been approved by triage owners.
Adding the do-not-merge/cherry-pick-not-approved label.

To merge this cherry pick:

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  2. AFTER it has been approved by approvers, please wait for the cherry-pick merging approval from triage owners.
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@JaySon-Huang This PR has conflicts, I have hold it.
Please resolve them or ask others to resolve them, then comment /unhold to remove the hold label.

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ti-chi-bot bot commented Aug 29, 2025

@ti-chi-bot: ## If you want to know how to resolve it, please read the guide in TiDB Dev Guide.

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[APPROVALNOTIFIER] This PR is NOT APPROVED

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@ti-chi-bot: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

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