infoschema: fix compatibility of auto_increment column value of INFORMATION_SCHEMA.TABLES by crazycs520 · Pull Request #10207 · pingcap/tidb

crazycs520 · 2019-04-20T15:07:39Z

What problem does this PR solve?

Fix compatibility of auto_increment column value of INFORMATION_SCHEMA.TABLES.

create table t1 (a int);
create table t (a int auto_increment key);
select table_name, auto_increment from `INFORMATION_SCHEMA`.`TABLES` where `TABLE_NAME` in ('t1','t');

In MySQL:

mysql > select table_name, auto_increment from `INFORMATION_SCHEMA`.`TABLES` where `TABLE_NAME` in ('t1','t');
+------------+----------------+
| table_name | auto_increment |
+------------+----------------+
| t          | 1              |
| t1         | <null>         |
+------------+----------------+

In TiDB:

tidb > select table_name, auto_increment from `INFORMATION_SCHEMA`.`TABLES` where `TABLE_NAME` in ('t1','t');
+------------+----------------+
| table_name | auto_increment |
+------------+----------------+
| t1         | 0              |
| t          | 1              |
+------------+----------------+

after This PR:
TiDB

create table t1 (a int,b int);
create table t (a int auto_increment key, b int);
select table_name, auto_increment from `INFORMATION_SCHEMA`.`TABLES` where `TABLE_NAME` in ('t1','t');
mysql>select table_name, auto_increment from `INFORMATION_SCHEMA`.`TABLES` where `TABLE_NAME` in ('t1','t');
+------------+----------------+
| table_name | auto_increment |
+------------+----------------+
| t1         | <null>         |
| t          | 0              |                    -- attention, this is still not comatible with mysql, this is cause by that tidb have not allocated auto_increate ID,  so the allocator is 0;
+------------+----------------+
2 rows in set
mysql>insert into t1 set b=1;
Query OK, 1 row affected
Time: 0.008s
mysql>insert into t set b=1;
Query OK, 1 row affected
Time: 0.014s
mysql>select table_name, auto_increment from `INFORMATION_SCHEMA`.`TABLES` where `TABLE_NAME` in ('t1','t');
+------------+----------------+
| table_name | auto_increment |
+------------+----------------+
| t1         | <null>         |
| t          | 2              |                          -- after tidb alloc auto_increament later, It will be compatible with mysql to show the next auto_increament.
+------------+----------------+

What is changed and how it works?

Change dataForTables function.

Check List

Tests

Unit test

Code changes

Has exported function/method change

Side effects

Related changes

Need to cherry-pick to the release branch?

…MATION_SCHEMA.TABLES

codecov · 2019-04-20T15:29:07Z

Codecov Report

Merging #10207 into master will increase coverage by 0.4707%.
The diff coverage is n/a.

@@               Coverage Diff               @@
##             master    #10207        +/-   ##
===============================================
+ Coverage   81.2882%   81.759%   +0.4707%     
===============================================
  Files           423       423                
  Lines         90387     92369      +1982     
===============================================
+ Hits          73474     75520      +2046     
+ Misses        11606     11544        -62     
+ Partials       5307      5305         -2

winkyao · 2019-04-22T03:16:43Z

-		if err != nil {
-			return 0, err
-		}
+	autoIncID, err := tbl.Allocator(ctx).NextGlobalAutoID(tblInfo.ID)


Could we use the nextAutoID in this autoid.allocator of this table, in the memory

But select table_name, auto_increment from NFORMATION_SCHEMA.TABLES from different-tidb-server will got different value.

….TABLES

… info-tables

winkyao

LGTM

zimulala

LGTM

crazycs520 · 2019-07-19T08:41:58Z

/run-all-tests

crazycs520 · 2019-07-19T09:05:16Z