This article describes the different methods MariaDB provides to limit/timeout a query:
The LIMIT clause restricts the number of returned rows.
Stops the query after 'rows_limit' number of rows have been examined.
If the variable is set, one can't execute an or
statement unless one specifies a key constraint in the WHERE clause or provide a LIMIT clause (or both).
acts as an automatic LIMIT row_count to any query.
The above is the same as:
If the variable (also called sql_max_join_size) is set, then it will limit
any SELECT statements that probably need to examine more thanMAX_JOIN_SIZE rows.
If the 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 .
variable
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SELECT ... LIMIT row_count
OR
SELECT ... LIMIT OFFSET, row_count
OR
SELECT ... LIMIT row_count OFFSET OFFSETSELECT ... LIMIT ROWS EXAMINED rows_limit;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 columnSET @@SQL_SELECT_LIMIT=1000
SELECT * FROM big_table;SELECT * FROM big_table LIMIT 1000;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