转：
I often noticed that people complain about the LOAD DATA performance when loading the table with large number of rows of data. Even today I saw a case where the LOAD DATA on a simple 3 column table with about 5 million rows taking ~15 minutes of time. This is because the server did not had any tuning in regards to bulk insertion.
Consider the following simple MyISAM table on Redhat Linux 32-bit.
| 1 2 3 4 5 6 7 8 | CREATE TABLE load1 ( `col1` varchar(100) NOT NULL default '', `col2` int(11) default NULL, `col3` char(1) default NULL, PRIMARY KEY (`col1`) ) TYPE=MyISAM; |
The table has a string key column. Here is the data file() that I used it for testing:
| 1 2 3 4 5 6 7 | [vanugant@escapereply:t55 tmp]$ wc loaddata.csv 5164946 5164946 227257389 loaddata.csv [vanugant@escapereply:t55 tmp]$ ls -alh loaddata.csv -rw-r--r-- 1 vanugant users 217M Nov 6 14:42 loaddata.csv [vanugant@escapereply:t55 tmp]$ |
Here is the default related to LOAD DATA:
| 1 2 3 4 5 6 7 8 9 10 | mysql> show variables; +-------------------------+---------+ | Variable_name | Value | +-------------------------+---------+ | bulk_insert_buffer_size | 8388608 | | myisam_sort_buffer_size | 16777216 | | key_buffer_size | 33554432 | +-------------------------+----------+ |
and here is the actual LOAD DATA query to load all ~5m rows (~256M of data) to the table and its timing.
| 1 2 3 4 5 | mysql> LOAD DATA INFILE '/home/vanugant/tmp/loaddata.csv' IGNORE INTO TABLE load1 FIELDS TERMINATED BY ','; Query OK, 4675823 rows affected (14 min 56.84 sec) Records: 5164946 Deleted: 0 Skipped: 489123 Warnings: 0 |
Now, lets experiment by disabling the keys in the table before running the LOAD DATA:
| 1 2 3 4 5 6 7 8 9 10 11 | mysql> SET SESSION BULK_INSERT_BUFFER_SIZE=314572800; Query OK, 0 rows affected (0.00 sec) mysql> alter table load1 disable keys; Query OK, 0 rows affected (0.00 sec) mysql> LOAD DATA INFILE '/home/vanugant/tmp/loaddata.csv' IGNORE INTO TABLE load1 FIELDS TERMINATED BY ','; Query OK, 4675823 rows affected (13 min 47.50 sec) Records: 5164946 Deleted: 0 Skipped: 489123 Warnings: 0 |
No use, just 1% increase or same…., now lets set the real MyISAM values… and try again…
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 | mysql> SET SESSION BULK_INSERT_BUFFER_SIZE=256217728; Query OK, 0 rows affected (0.00 sec) mysql> set session MYISAM_SORT_BUFFER_SIZE=256217728; Query OK, 0 rows affected (0.00 sec) mysql> set global KEY_BUFFER_SIZE=256217728; Query OK, 0 rows affected (0.05 sec) mysql> alter table load1 disable keys; Query OK, 0 rows affected (0.00 sec) mysql> LOAD DATA INFILE '/home/vanugant/tmp/loaddata.csv' IGNORE INTO TABLE load1 FIELDS TERMINATED BY ','; Query OK, 4675823 rows affected (1 min 55.05 sec) Records: 5164946 Deleted: 0 Skipped: 489123 Warnings: 0 mysql> alter table load1 enable keys; Query OK, 0 rows affected (0.00 sec) |
Wow…thats almost 90% increase in the performance. So, disabling the keys in MyISAM is not just the key, but tuning the buffer size does play role based on the input data.
For the same case with Innodb, here is the status by adjusting the Innodb_buffer_pool_size=1G andInnodb_log_file_size=256M along with innodb_flush_logs_at_trx_commit=1.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | mysql> show variables like '%innodb%size'; +---------------------------------+------------+ | Variable_name | Value | +---------------------------------+------------+ | innodb_additional_mem_pool_size | 26214400 | | innodb_buffer_pool_size | 1073741824 | | innodb_log_buffer_size | 8388608 | | innodb_log_file_size | 268435456 | +---------------------------------+------------+ mysql> LOAD DATA INFILE '/home/vanugant/tmp/loaddata.csv' IGNORE INTO TABLE load1 FIELDS TERMINATED BY ','; Query OK, 4675823 rows affected (2 min 37.53 sec) Records: 5164946 Deleted: 0 Skipped: 489123 Warnings: 0 |
With innodb_flush_logs_at_trx_commit=2, innodb_flush_method=O_DIRECT and innodb_doublewrite=0; it will be another 40% difference (use all these variables with caution, unless you know what you are doing)
| 1 2 3 4 5 | mysql> LOAD DATA INFILE '/home/vanugant/tmp/loaddata.csv' IGNORE INTO TABLE load1 FIELDS TERMINATED BY ','; Query OK, 4675823 rows affected (1 min 53.69 sec) Records: 5164946 Deleted: 0 Skipped: 489123 Warnings: 0 |