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ti-chi-bot merged 2 commits into from
Apr 22, 2024
Merged

ebnf show table next rowid (#17093) #17303

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ebnf show table next rowid
dveeden Apr 9, 2024
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Update wording
lilin90 Apr 22, 2024
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25 changes: 10 additions & 15 deletions sql-statements/sql-statement-show-table-next-rowid.md
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Expand Up @@ -7,34 +7,29 @@ summary: Learn the usage of `SHOW TABLE NEXT_ROW_ID` in TiDB.

`SHOW TABLE NEXT_ROW_ID` is used to show the details of some special columns of a table, including:

* `AUTO_INCREMENT` column automatically created by TiDB, namely, `_tidb_rowid` column.
* [`AUTO_INCREMENT`](/auto-increment.md) column automatically created by TiDB, namely, `_tidb_rowid` column.
* `AUTO_INCREMENT` column created by users.
* [`AUTO_RANDOM`](/auto-random.md) column created by users.
* [`SEQUENCE`](/sql-statements/sql-statement-create-sequence.md) created by users.

## Synopsis

**ShowTableNextRowIDStmt:**

![ShowTableNextRowIDStmt](/media/sqlgram/ShowTableNextRowIDStmt.png)

**TableName:**

![TableName](/media/sqlgram/TableName.png)
```ebnf+diagram
ShowTableNextRowIDStmt ::=
"SHOW" "TABLE" (SchemaName ".")? TableName "NEXT_ROW_ID"
```

## Examples

For newly created tables, `NEXT_GLOBAL_ROW_ID` is `1` because no Row ID is allocated.

{{< copyable "sql" >}}

```sql
create table t(a int);
CREATE TABLE t(a int);
Query OK, 0 rows affected (0.06 sec)
```

```sql
show table t next_row_id;
SHOW TABLE t NEXT_ROW_ID;
+---------+------------+-------------+--------------------+
| DB_NAME | TABLE_NAME | COLUMN_NAME | NEXT_GLOBAL_ROW_ID |
+---------+------------+-------------+--------------------+
Expand All @@ -43,16 +38,16 @@ show table t next_row_id;
1 row in set (0.00 sec)
```

Data have been written to the table. The TiDB server that inserts the data allocates and caches 30000 IDs at once. Thus, NEXT_GLOBAL_ROW_ID is 30001 now.
Data have been written to the table. The TiDB server that inserts the data allocates and caches 30000 IDs at once. Thus, NEXT_GLOBAL_ROW_ID is 30001 now. The number of IDs is controlled by [`AUTO_ID_CACHE`](/auto-increment.md#auto_id_cache).

```sql
insert into t values (), (), ();
INSERT INTO t VALUES (), (), ();
Query OK, 3 rows affected (0.02 sec)
Records: 3 Duplicates: 0 Warnings: 0
```

```sql
show table t next_row_id;
SHOW TABLE t NEXT_ROW_ID;
+---------+------------+-------------+--------------------+
| DB_NAME | TABLE_NAME | COLUMN_NAME | NEXT_GLOBAL_ROW_ID |
+---------+------------+-------------+--------------------+
Expand Down