# Query Limits and Timeouts

This article describes the different methods MariaDB provides to limit/timeout a query:

## [LIMIT](https://mariadb.com/docs/server/reference/sql-statements/data-manipulation/selecting-data/select#limit)

```sql
SELECT ... LIMIT row_count
OR
SELECT ... LIMIT OFFSET, row_count
OR
SELECT ... LIMIT row_count OFFSET OFFSET
```

The [LIMIT](https://mariadb.com/docs/server/reference/sql-statements/data-manipulation/selecting-data/select#limit) clause restricts the number of returned rows.

## [LIMIT ROWS EXAMINED](https://mariadb.com/docs/server/ha-and-performance/optimization-and-tuning/query-optimizations/limit-rows-examined)

```sql
SELECT ... LIMIT ROWS EXAMINED rows_limit;
```

Stops the query after 'rows\_limit' number of rows have been examined.

## sql\_safe\_updates

If the [sql\_safe\_updates](https://mariadb.com/docs/server/server-management/variables-and-modes/server-system-variables#sql_safe_updates) variable is set, one can't execute an [UPDATE](https://mariadb.com/docs/server/reference/sql-statements/data-manipulation/changing-deleting-data/update) or [DELETE](https://mariadb.com/docs/server/reference/sql-statements/data-manipulation/changing-deleting-data/delete)\
statement unless one specifies a key constraint in the `WHERE` clause or provide a `LIMIT` clause (or both).

```sql
SET @@SQL_SAFE_UPDATES=1
UPDATE tbl_name SET not_key_column=val;
-> ERROR 1175 (HY000): You are using safe update mode 
  and you tried to update a table without a WHERE that uses a KEY column
```

## sql\_select\_limit

[sql\_select\_limit](https://mariadb.com/docs/server/server-management/variables-and-modes/server-system-variables#sql_select_limit) acts as an automatic `LIMIT row_count` to any [SELECT](https://mariadb.com/docs/server/reference/sql-statements/data-manipulation/selecting-data/select) query.

```sql
SET @@SQL_SELECT_LIMIT=1000
SELECT * FROM big_table;
```

The above is the same as:

```
SELECT * FROM big_table LIMIT 1000;
```

## max\_join\_size

If the [max\_join\_size](https://mariadb.com/docs/server/server-management/variables-and-modes/server-system-variables#max_join_size) variable (also called `sql_max_join_size`) is set, then it will limit\
any SELECT statements that probably need to examine more than`MAX_JOIN_SIZE` rows.

```sql
SET @@MAX_JOIN_SIZE=1000;
->ERROR 1104 (42000): The SELECT would examine more than MAX_JOIN_SIZE ROWS; 
SELECT COUNT(null_column) FROM big_table;
  CHECK your WHERE AND USE SET SQL_BIG_SELECTS=1 OR SET MAX_JOIN_SIZE=# IF the SELECT IS okay
```

## max\_statement\_time

If the [max\_statement\_time](https://mariadb.com/docs/server/server-management/variables-and-modes/server-system-variables#max_statement_time) variable is set, any query (excluding stored procedures) taking longer than the value of `max_statement_time` (specified in seconds) to execute will be aborted. This can be set globally, by session, as well as per user and per query. See [Aborting statements that take longer than a certain time to execute](https://mariadb.com/docs/server/ha-and-performance/optimization-and-tuning/query-optimizations/aborting-statements).

## See Also

* [WAIT and NOWAIT](https://mariadb.com/docs/server/reference/sql-statements/transactions/wait-and-nowait)
* [Aborting statements that take longer than a certain time to execute](https://mariadb.com/docs/server/ha-and-performance/optimization-and-tuning/query-optimizations/aborting-statements)
* [lock\_wait\_timeout](https://mariadb.com/docs/server/server-management/variables-and-modes/server-system-variables#lock_wait_timeout) variable

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