bindinfo: add last_used_date to track bindinfo usage frequency #63409

hawkingrei · 2025-09-08T09:23:00Z

What problem does this PR solve?

Issue Number: close #63407

Problem Summary:

What changed and how does it work?

Currently, some customers have created a large number of bindings. However, it is difficult to determine whether these bindings are still in use. The sheer volume of bindings also puts pressure on TiDB. Therefore, we need a way to identify and mark the bindings that are not in use.

Check List

Tests

Unit test
Integration test
Manual test (add detailed scripts or steps below)

start a tidb with master which is started by script. Tikv and PD is started by tiup playground nightly --mode tikv-slim.

+----------------------------------+----------------------------------+------------+---------+-------------------------+-------------------------+---------+-----------+---------+------------+-------------+
| original_sql                     | bind_sql                         | default_db | status  | create_time             | update_time             | charset | collation | source  | sql_digest | plan_digest |
+----------------------------------+----------------------------------+------------+---------+-------------------------+-------------------------+---------+-----------+---------+------------+-------------+
| builtin_pseudo_sql_for_bind_lock | builtin_pseudo_sql_for_bind_lock | mysql      | builtin | 0000-00-00 00:00:00.000 | 0000-00-00 00:00:00.000 |         |           | builtin | <null>     | <null>      |
+----------------------------------+----------------------------------+------------+---------+-------------------------+-------------------------+---------+-----------+---------+------------+-------------+

kill this TiDB and start changed tidb verson.

+----------------------------------+----------------------------------+------------+---------+-------------------------+-------------------------+---------+-----------+---------+------------+-------------+----------------+
| original_sql                     | bind_sql                         | default_db | status  | create_time             | update_time             | charset | collation | source  | sql_digest | plan_digest | last_used_time |
+----------------------------------+----------------------------------+------------+---------+-------------------------+-------------------------+---------+-----------+---------+------------+-------------+----------------+
| builtin_pseudo_sql_for_bind_lock | builtin_pseudo_sql_for_bind_lock | mysql      | builtin | 0000-00-00 00:00:00.000 | 0000-00-00 00:00:00.000 |         |           | builtin | <null>     | <null>      | <null>         |
+----------------------------------+----------------------------------+------------+---------+-------------------------+-------------------------+---------+-----------+---------+------------+-------------+----------------+

No need to test
- I checked and no code files have been changed.

Side effects

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

Documentation

Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

None

codecov · 2025-09-08T10:47:18Z

Codecov Report

❌ Patch coverage is 81.10236% with 24 lines in your changes missing coverage. Please review.
✅ Project coverage is 75.5088%. Comparing base (4f57389) to head (a45b570).
⚠️ Report is 10 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #63409        +/-   ##
================================================
+ Coverage   72.7332%   75.5088%   +2.7755%     
================================================
  Files          1848       1895        +47     
  Lines        498692     514696     +16004     
================================================
+ Hits         362715     388641     +25926     
+ Misses       113968     102798     -11170     
- Partials      22009      23257      +1248

Flag	Coverage Δ
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unit	`73.0139% <70.8661%> (+0.7639%)`	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
dumpling	`52.8700% <ø> (ø)`
parser	`∅ <ø> (∅)`
br	`63.3775% <ø> (+16.9514%)`	⬆️

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hawkingrei · 2025-09-09T02:13:45Z

/retest

hawkingrei · 2025-09-09T06:12:46Z

/retest

hawkingrei · 2025-09-09T07:46:05Z

/retest

hawkingrei · 2025-09-12T09:10:53Z

/retest

hawkingrei · 2025-09-16T03:36:37Z

/retest

AilinKid · 2025-09-16T06:52:44Z

/retest-required

qw4990 · 2025-09-16T08:18:13Z

pkg/session/bootstrap.go

 		source VARCHAR(10) NOT NULL DEFAULT 'unknown',
 		sql_digest varchar(64) DEFAULT NULL,
 		plan_digest varchar(64) DEFAULT NULL,
+		last_used_time TIMESTAMP DEFAULT NULL,


Please also specify the precision, @henrybw just updated the precision to 6 to fix some unstable problems: https://github.com/pingcap/tidb/pull/63524/files

qw4990 · 2025-09-16T09:17:23Z

pkg/bindinfo/utils.go

+)
+
+func updateBindingUsageInfoToStorage(sPool util.DestroyableSessionPool, bindings []*Binding) error {
+	err := callWithSCtx(sPool, true, func(sctx sessionctx.Context) error {


In one of our customer's workload, there are around 100,000 bindings, is this OK to execute 100,000 update statements in one transaction?

It's better to limit the number of update statements in this transaction to around 200 or 500 for safety I think. Better to confirm this with our Txn Team members.

OK, I will confirm this with the transaction team.

Additionally, if a cluster really has that many binds, there must also be many TiDB instances. In fact, we need to consider the impact on the entire cluster from multiple instances. So as long as it is sufficiently scattered, with small batches and executed by multiple instances, it should be fine.

The slow write here actually won't have much impact. DBAs won't delete a bindinfo just because it hasn't been used for a day or two; that would be quite risky.

pkg/bindinfo/binding.go

hawkingrei · 2025-09-16T13:51:23Z

/retest

henrybw

This doesn't seem to load usage info from storage into the bindings cache? I think we need to also update readBindingsFromStorage() to read the last_used_time column into the Binding structures.

henrybw · 2025-09-17T00:54:23Z

pkg/domain/domain.go

+					randomDuration(
+						bindinfo.MinCheckIntervalForUpdateBindingUsageInfo,
+						bindinfo.MaxCheckIntervalForUpdateBindingUsageInfo,
+					),


Picking random durations seems unnecessarily complicated. What's wrong with picking just one check interval?

Because the customer's cluster has many TiDB nodes, especially for SaaS clusters, we need to avoid having all TiDB nodes execute batch updates at the same time, which could impact the customer's business. Additionally, updating bindinfo is not urgent, so it's fine to have larger time intervals between updates. Moreover, the code for this is not extensive.

In the current code, there is also a random interval inside the deltaUpdateTickerWorker.

pkg/domain/domain.go

pkg/bindinfo/utils.go

pkg/bindinfo/tests/bind_usage_info_test.go

time-and-fate

In the current implementation, if the tidb server shuts down in 6 hours, the usage info will never get a chance to be recorded.
I think we need to confirm with PM that this is the expected behavior.

pkg/bindinfo/binding_cache.go

time-and-fate · 2025-09-17T02:57:16Z

pkg/bindinfo/utils.go

+				}
+				binding.ResetUsageInfo()
+			}
+			if cnt > updateBindingUsageInfoBatchSize {


cnt is never updated.

I have updated.

time-and-fate · 2025-09-17T02:57:29Z

pkg/bindinfo/utils.go

+	lastUsedTime := ts.UTC().Format(types.TimeFormat)
+	_, _, err := execRows(
+		sctx,
+		"UPDATE mysql.bind_info SET last_used_time = CONVERT_TZ(%?, '+00:00', @@TIME_ZONE) WHERE sql_digest = %?",


I think this would be a table full scan.

hawkingrei · 2025-09-17T03:33:09Z

This doesn't seem to load usage info from storage into the bindings cache? I think we need to also update readBindingsFromStorage() to read the last_used_time column into the Binding structures.

Yes, it is only for the user to check whether the bind is in use.

Signed-off-by: Weizhen Wang <[email protected]>

Copilot

Pull Request Overview

This PR adds a last_used_date column to the mysql.bind_info table to track binding usage frequency, helping customers identify unused bindings that may be putting pressure on TiDB.

Key changes:

Adds new database schema column and upgrade mechanism for version 253
Implements usage tracking that updates binding last-used timestamps when bindings are matched
Adds periodic storage updates with randomized intervals to prevent thundering herd problems

Reviewed Changes

Copilot reviewed 17 out of 17 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
pkg/session/upgrade.go	Adds version 253 upgrade function to add `last_used_date` column
pkg/session/bootstrap.go	Updates bind_info table schema to include new column
pkg/bindinfo/binding.go	Adds usage tracking fields and methods to Binding struct
pkg/bindinfo/utils.go	Implements batch update logic for writing usage info to storage
pkg/bindinfo/binding_cache.go	Adds interface method for updating usage info to storage
pkg/domain/domain.go	Adds periodic worker to update binding usage info with randomized intervals
pkg/bindinfo/tests/bind_usage_info_test.go	Comprehensive test coverage for new usage tracking functionality
Multiple test files	Updates existing tests to handle new column in insert statements

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

pkg/session/bootstrap_test.go

pkg/bindinfo/utils.go

Signed-off-by: Weizhen Wang <[email protected]>

henrybw

Almost there.

pkg/bindinfo/utils.go

pkg/bindinfo/tests/bind_usage_info_test.go

pkg/session/bootstrap_test.go

Signed-off-by: Weizhen Wang <[email protected]>

henrybw

Thank you for diligently working through this. LGTM

hawkingrei · 2025-09-30T02:38:00Z

/unhold

ti-chi-bot · 2025-09-30T04:30:07Z

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: D3Hunter, henrybw, Leavrth, qw4990, you06, yudongusa

The full list of commands accepted by this bot can be found here.

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Needs approval from an approver in each of these files:

~~OWNERS~~ [D3Hunter,Leavrth,qw4990,you06]
~~br/OWNERS~~ [Leavrth]
~~pkg/bindinfo/OWNERS~~ [henrybw,qw4990]
~~pkg/domain/OWNERS~~ [D3Hunter]
~~pkg/infoschema/OWNERS~~ [D3Hunter]
~~pkg/session/OWNERS~~ [yudongusa]

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hawkingrei · 2025-09-30T07:26:49Z

/retest

ti-chi-bot · 2025-09-30T08:13:18Z

@hawkingrei: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
idc-jenkins-ci-tidb/mysql-test	`a45b570`	link	unknown	`/test mysql-test`

Full PR test history. Your PR dashboard.

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hawkingrei · 2025-09-30T08:56:55Z

/cherrypick release-8.5

Signed-off-by: ti-chi-bot <[email protected]>

ti-chi-bot · 2025-09-30T08:57:39Z

@hawkingrei: new pull request created to branch release-8.5: #63824.
But this PR has conflicts, please resolve them!

In response to this:

/cherrypick release-8.5

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bindinfo: add last_used_date to track bindinfo usage frequency (#63409) #63824

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…ap#63409) close pingcap#63407

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This is an automated cherry-pick of pingcap#63409

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bindinfo: add last_used_date to track bindinfo usage frequency #63409

bindinfo: add last_used_date to track bindinfo usage frequency #63409

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