I've got a windows 7 64 bit machine that I'm using for some load testing of a mysql db. My program uses sqlalchemy to connect and run several load from infile statements on said database. These bulk loads all happen within a single transaction, all keys are disabled beforehand, and each csv file is only a few megabytes large.

The problem I've run into is that the test machine gets IO bound. It has enough ram available (12G) to hold the entire transaction in memory and do a single flush out the other end. As far as I understand the manual, the innodb tables shouldn't touch the hard drive until it flushes the dirty pages at transaction completion.

The total data to be loaded is about 1G, spread across the different tables. It ends up taking 37 minutes to load it all. Here's my current test settings for perusal. I'd also be happy to report the results from show engine innodb status or similar queries if necessary.

To recap, I need to know if 37 minutes is a fast insert speed for this data size, and what I can do to increase the insert speed.


Whoops! I forgot some important info.

Mysql version 5.5
Server has 12G total ram
Total rows inserted ~2,597,240
  • How many rows are you inserting? Commented Jul 13, 2012 at 20:25
  • Question: What version of MySQL are you using ??? Commented Jul 13, 2012 at 20:26
  • How much RAM on the DB Server ??? Commented Jul 13, 2012 at 20:28
  • @AaronBrown I've updated the question. for anyone else, if I need to add more details, just ask. Commented Jul 13, 2012 at 20:40
  • How big is your innodb_log_file_size? It would be best to post all your innodb_% variables with SHOW GLOBAL VARIABLES LIKE 'innodb_%';. Commented Jul 13, 2012 at 21:03

2 Answers 2


Your bulk insert buffer is 4G. That's great ... FOR MyISAM !!!

InnoDB does not use the bulk insert buffer.

You may need to have sqlalchemy throttle the load data infile calls into multiple transactions.

You may also want to disable innodb_change_buffering, setting it to inserts. Unfortunately, you cannot do SET GLOBAL innodb_change_buffering = 'inserts';. If you dom you may need to set it in my.cnf and restart mysql.

UPDATE 2012-07-13 16:53 EDT

I just noticed that you have two values in the my.cnf for innodb_buffer_pool_size. First one is 2385M, and the last one is 14G. If MySQL for Windows accepted 14G and you only have 12G of RAM, your server must be having a good old time swapping.

You can verify what the buffer pool size is with

SHOW VARIABLES LIKE 'innodb_buffer_pool_size';

UPDATE 2012-07-13 16:58 EDT

You may also want to check how full the buffer pool is with this

SELECT FORMAT(A.num * 100.0 / B.num,2) BufferPoolFullPct FROM
(SELECT variable_value num FROM information_schema.global_status
WHERE variable_name = 'Innodb_buffer_pool_pages_data') A,
(SELECT variable_value num FROM information_schema.global_status
WHERE variable_name = 'Innodb_buffer_pool_pages_total') B;
  • Wouldn't turning off change buffering make my problem worse? More writes to disk, instead of less? Commented Jul 13, 2012 at 20:39
  • You are right. Switching answer ... Commented Jul 13, 2012 at 20:47
  • As of MySQL 5.7.6, use performance_schema.global_status instead of information_schema.global_status for the "BufferPoolFullPct" query. docs.oracle.com/cd/E17952_01/mysql-5.7-en/… Commented Nov 16, 2021 at 3:15


Sorry I couldn't get back here earlier, things ended up getting very busy for a while. I appreciate all the help from everyone. It seems part of the problem was that some options do not accept OFF|ON as their values.

Other than that, just setting my innodb_io_capacity value higher seems to have done the trick. I also have to have a large enough setting for the innodb_buffer_pool_size otherwise Mysql does not have enough space for the bulk inserts, since approx. 25% of the buffer size is allowed I think.

With these settings it holds flushing until an entire bulk insert is done, and then flushes to the hard drive. I get about 20-25MB write speed with pauses as it waits for the next insert, instead of the constant 1MB write speed I used to have.

The only improvement left is to add enough ram to the box for it to support the workload.

Here's my settings if anyone is interested:

# MySQL Server Instance Configuration File
# ----------------------------------------------------------------------
# Generated by the MySQL Server Instance Configuration Wizard
# Installation Instructions
# ----------------------------------------------------------------------
# On Linux you can copy this file to /etc/my.cnf to set global options,
# mysql-data-dir/my.cnf to set server-specific options
# (@localstatedir@ for this installation) or to
# ~/.my.cnf to set user-specific options.
# On Windows you should keep this file in the installation directory 
# of your server (e.g. C:\Program Files\MySQL\MySQL Server X.Y). To
# make sure the server reads the config file use the startup option 
# "--defaults-file". 
# To run run the server from the command line, execute this in a 
# command line shell, e.g.
# mysqld --defaults-file="C:\Program Files\MySQL\MySQL Server X.Y\my.ini"
# To install the server as a Windows service manually, execute this in a 
# command line shell, e.g.
# mysqld --install MySQLXY --defaults-file="C:\Program Files\MySQL\MySQL Server X.Y\my.ini"
# And then execute this in a command line shell to start the server, e.g.
# net start MySQLXY
# Guildlines for editing this file
# ----------------------------------------------------------------------
# In this file, you can use all long options that the program supports.
# If you want to know the options a program supports, start the program
# with the "--help" option.
# More detailed information about the individual options can also be
# found in the manual.
# ----------------------------------------------------------------------
# The following options will be read by MySQL client applications.
# Note that only client applications shipped by MySQL are guaranteed
# to read this section. If you want your own MySQL client program to
# honor these values, you need to specify it as an option during the
# MySQL client library initialization.




# ----------------------------------------------------------------------
# The following options will be read by the MySQL Server. Make sure that
# you have installed the server correctly (see above) so it reads this 
# file.

# The TCP/IP Port the MySQL Server will listen on

#Path to installation directory. All paths are usually resolved relative to this.
basedir="C:/Program Files/MySQL/MySQL Server 5.5/"

#Path to the database root
datadir="C:/ProgramData/MySQL/MySQL Server 5.5/Data/"

# The default character set that will be used when a new schema or table is
# created and no character set is defined

# The default storage engine that will be used when create new tables when

# The maximum amount of concurrent sessions the MySQL server will
# allow. One of these connections will be reserved for a user with
# SUPER privileges to allow the administrator to login even if the
# connection limit has been reached.

# Query cache is used to cache SELECT results and later return them
# without actual executing the same query once again. Having the query
# cache enabled may result in significant speed improvements, if your
# have a lot of identical queries and rarely changing tables. See the
# "Qcache_lowmem_prunes" status variable to check if the current value
# is high enough for your load.
# Note: In case your tables change very often or if your queries are
# textually different every time, the query cache may result in a
# slowdown instead of a performance improvement.

# The number of open tables for all threads. Increasing this value
# increases the number of file descriptors that mysqld requires.
# Therefore you have to make sure to set the amount of open files
# allowed to at least 4096 in the variable "open-files-limit" in
# section [mysqld_safe]

# Maximum size for internal (in-memory) temporary tables. If a table
# grows larger than this value, it is automatically converted to disk
# based table This limitation is for a single table. There can be many
# of them.

# How many threads we should keep in a cache for reuse. When a client
# disconnects, the client's threads are put in the cache if there aren't
# more than thread_cache_size threads from before.  This greatly reduces
# the amount of thread creations needed if you have a lot of new
# connections. (Normally this doesn't give a notable performance
# improvement if you have a good thread implementation.)

#*** MyISAM Specific options

# The maximum size of the temporary file MySQL is allowed to use while
# recreating the index (during REPAIR, ALTER TABLE or LOAD DATA INFILE.
# If the file-size would be bigger than this, the index will be created
# through the key cache (which is slower).

# If the temporary file used for fast index creation would be bigger
# than using the key cache by the amount specified here, then prefer the
# key cache method.  This is mainly used to force long character keys in
# large tables to use the slower key cache method to create the index.

# Size of the Key Buffer, used to cache index blocks for MyISAM tables.
# Do not set it larger than 30% of your available memory, as some memory
# is also required by the OS to cache rows. Even if you're not using
# MyISAM tables, you should still set it to 8-64M as it will also be
# used for internal temporary disk tables.

# Size of the buffer used for doing full table scans of MyISAM tables.
# Allocated per thread, if a full scan is needed.

# This buffer is allocated when MySQL needs to rebuild the index in
# REPAIR, OPTIMZE, ALTER table statements as well as in LOAD DATA INFILE
# into an empty table. It is allocated per thread so be careful with
# large settings.

#*** INNODB Specific options ***

# Use this option if you have a MySQL server with InnoDB support enabled
# but you do not plan to use it. This will save memory and disk space
# and speed up some things.

# Additional memory pool that is used by InnoDB to store metadata
# information.  If InnoDB requires more memory for this purpose it will
# start to allocate it from the OS.  As this is fast enough on most
# recent operating systems, you normally do not need to change this
# value. SHOW INNODB STATUS will display the current amount used.

# If set to 1, InnoDB will flush (fsync) the transaction logs to the
# disk at each commit, which offers full ACID behavior. If you are
# willing to compromise this safety, and you are running small
# transactions, you may set this to 0 or 2 to reduce disk I/O to the
# logs. Value 0 means that the log is only written to the log file and
# the log file flushed to disk approximately once per second. Value 2
# means the log is written to the log file at each commit, but the log
# file is only flushed to disk approximately once per second.

# The size of the buffer InnoDB uses for buffering log data. As soon as
# it is full, InnoDB will have to flush it to disk. As it is flushed
# once per second anyway, it does not make sense to have it very large
# (even with long transactions).

# InnoDB, unlike MyISAM, uses a buffer pool to cache both indexes and
# row data. The bigger you set this the less disk I/O is needed to
# access data in tables. On a dedicated database server you may set this
# parameter up to 80% of the machine physical memory size. Do not set it
# too large, though, because competition of the physical memory may
# cause paging in the operating system.  Note that on 32bit systems you
# might be limited to 2-3.5G of user level memory per process, so do not
# set it too high.

# Size of each log file in a log group. You should set the combined size
# of log files to about 25%-100% of your buffer pool size to avoid
# unneeded buffer pool flush activity on log file overwrite. However,
# note that a larger logfile size will increase the time needed for the
# recovery process.

# Number of threads allowed inside the InnoDB kernel. The optimal value
# depends highly on the application, hardware as well as the OS
# scheduler properties. A too high value may lead to thread thrashing.

# Added by RCW, 2012.07.13







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