expression: support tidb encode key function

[tangenta]

What problem does this PR solve?

Issue Number: close #51683

Problem Summary: See #51683.

What changed and how does it work?

This PR supports three builtin functions, namely tidb_mvcc_info(), tidb_encode_record_key() and tidb_encode_index_key():

• tidb_mvcc_info(key) returns MVCC information of a given key.
• tidb_encode_record_key(dbName, tableName, handle/pk columns...) returns a row record key. The table must exist.
• tidb_encode_index_key(dbName, tableName, indexName, idx columns..., handle/pk columns...) returns a index record key. The index must exist.

Please also note that tableName can be one of formats as below:

• t: refer to non-partitioned table t.
• t(p1): refer to partition table t and the partition p1.

mysql> create table t (a int, b int, c timestamp, primary key (a) clustered, index idx_c(c));
Query OK, 0 rows affected (0.14 sec)

mysql> insert into t values (1, 1, now());
Query OK, 1 row affected (0.00 sec)

mysql> table t;
+---+------+---------------------+
| a | b    | c                   |
+---+------+---------------------+
| 1 |    1 | 2024-03-12 11:14:35 |
+---+------+---------------------+
1 row in set (0.00 sec)

mysql> select tidb_encode_record_key('test', 't', 1);
+----------------------------------------+
| tidb_encode_record_key('test', 't', 1) |
+----------------------------------------+
| 7480000000000000705f728000000000000001 |
+----------------------------------------+
1 row in set (0.00 sec)

mysql> select tidb_mvcc_info('7480000000000000705f728000000000000001');
+-----------------------------------------------------------------------------------------------------------------------------------+
| tidb_mvcc_info('7480000000000000705f728000000000000001')                                                                          |
+-----------------------------------------------------------------------------------------------------------------------------------+
| {"info":{"writes":[{"start_ts":448322148825038849,"commit_ts":448322148825038850,"short_value":"gAACAAAAAgMBAAkAAQAAAKMz2LIZ"}]}} |
+-----------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql> select tidb_encode_index_key('test', 't', 'idx_c', '2024-03-12 11:14:35', 1);
+----------------------------------------------------------------------------+
| tidb_encode_index_key('test', 't', 'idx_c', '2024-03-12 11:14:35', 1)      |
+----------------------------------------------------------------------------+
| 7480000000000000705f6980000000000000010419b2d833a3000000038000000000000001 |
+----------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql> select tidb_decode_key(tidb_encode_index_key('test', 't', 'idx_c', '2024-03-12 11:14:35', 1));
+----------------------------------------------------------------------------------------+
| tidb_decode_key(tidb_encode_index_key('test', 't', 'idx_c', '2024-03-12 11:14:35', 1)) |
+----------------------------------------------------------------------------------------+
| {"index_id":1,"index_vals":{"c":"2024-03-12 11:14:35"},"table_id":112}                 |
+----------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql> select tidb_mvcc_info(tidb_encode_index_key('test', 't', 'idx_c', '2024-03-12 11:14:35', 1));
+-----------------------------------------------------------------------------------------------------------+
| tidb_mvcc_info(tidb_encode_index_key('test', 't', 'idx_c', '2024-03-12 11:14:35', 1))                     |
+-----------------------------------------------------------------------------------------------------------+
| {"info":{"writes":[{"start_ts":448322148825038849,"commit_ts":448322148825038850,"short_value":"MA=="}]}} |
+-----------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

Check List

Tests

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

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

Release note

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

None

[tiprow]

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[codecov]

Codecov Report

Attention: Patch coverage is 59.80392% with 205 lines in your changes missing coverage. Please review.

Project coverage is 56.6772%. Comparing base (782f08c) to head (bd28383).
Report is 22 commits behind head on master.

Additional details and impacted files

@@                Coverage Diff                @@
##             master     #51678         +/-   ##
=================================================
- Coverage   72.8726%   56.6772%   -16.1955%     
=================================================
  Files          1598       1729        +131     
  Lines        444224     630892     +186668     
=================================================
+ Hits         323718     357572      +33854     
- Misses       100549     249723     +149174     
- Partials      19957      23597       +3640     

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unit	72.6300% <58.4313%> (+0.6490%)	⬆️

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Components	Coverage Δ
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[ti-chi-bot]

PR needs rebase.

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[ekexium]

I love this
We need this
Please do continue this

[D3Hunter]

i hope those functions would works in normal query like :

select tidb_handle(), tidb_idx_key(index-name) from test.t where id = 1
select tidb_mvcc(tidb_handle()) from test.t where id = 1

[tangenta]

@D3Hunter If we put this in normal query, I think we cannot get the MVCC of deleted rows/indexes?

[kennytm]

@D3Hunter I don't think a function should need or be able to know the current plan is a SELECT operating on exactly one physical table.

[kennytm]

This must not be merged before the privilege check bypass is fixed.

See #51683 (comment) for a PoC.

[D3Hunter]

i hope those functions would works in normal query like :

select tidb_handle(), tidb_idx_key(index-name) from test.t where id = 1
select tidb_mvcc(tidb_handle()) from test.t where id = 1

ok, for downvoters, get from query is much simplier, i don't like to input so many parameters to just get the key of it, and it's error-prone to do that as we have to remember the definition of the pk/index. also privilige check is easier, by reuse existing one.

If we put this in normal query, I think we cannot get the MVCC of deleted rows/indexes?

can use as of timestamp?

I don't think a function should need or be able to know the current plan is a SELECT operating on exactly one physical table.

don't get your point, where is a function should need or be able to know the current plan is a SELECT operating on exactly one physical table. rule came from?

[kennytm]

@D3Hunter what is the result of tidb_handle() in the following?

select tidb_handle() from a, b;
select tidb_handle() from dual;
select tidb_handle() from (select * from t) _;

create view v as select 1;
select tidb_handle() from v;

[D3Hunter]

@D3Hunter what is the result of tidb_handle() in the following?

select tidb_handle() from a, b;
select tidb_handle() from dual;
select tidb_handle() from (select * from t) _;

create view v as select 1;
select tidb_handle() from v;

if we use the pattern, just check and report error in this case

[D3Hunter]

please ask PM for approval for new feature

[D3Hunter]

/hold

unhold it after PM approve

[ti-chi-bot]

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

Test name	Commit	Details	Required	Rerun command
pull-br-integration-test	78c5c63	link	true	/test pull-br-integration-test
pull-lightning-integration-test	78c5c63	link	true	/test pull-lightning-integration-test

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[ti-chi-bot]

@Frank945946: adding LGTM is restricted to approvers and reviewers in OWNERS files.

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[tangenta]

/retest

[tiprow]

@tangenta: Cannot trigger testing until a trusted user reviews the PR and leaves an /ok-to-test message.

In response to this:

/retest

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-06-14 15:52:24.810574996 +0000 UTC m=+739098.863886920: ✖️🔁 reset by kennytm.
• 2024-09-03 09:36:06.780380988 +0000 UTC m=+350691.298433913: ☑️ agreed by kennytm.
• 2024-09-05 09:25:51.146288226 +0000 UTC m=+522875.664341150: ☑️ agreed by wjhuang2016.

[D3Hunter]

/unhold

[D3Hunter]

add some test for user privileges?

[tangenta]

/approve

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Frank945946, kennytm, tangenta, time-and-fate, wjhuang2016, XuHuaiyu

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Needs approval from an approver in each of these files:

• OWNERS [XuHuaiyu,kennytm,tangenta,time-and-fate,wjhuang2016]
• pkg/expression/OWNERS [XuHuaiyu]
• pkg/parser/OWNERS [tangenta]
• pkg/planner/OWNERS [time-and-fate]

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[tangenta]

/ok-to-test