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Why is MySQL InnoDB much slower when scanning a table completely than MyISAM?

EDIT

The OP admitted a PostgreSQL profiling error in its answer below. I am updating this question to reflect the comparison between MyISAM and InnoDB.

Hello,

I ran a test against MySQL InnoDB, MyISAM, and PostgreSQL to see how well each of these engines performed a full table scan to understand what response times might be when we inevitably need this to happen.

Tests were conducted on Intel Core 2 Quad Q6600 @ 2.4Ghz w / 4 GB of RAM and 7200 rpm HD with a cache of 16 MB.

MySQL version was 5.0.67-community-nt-log 32-bit, PGSQL version was 8.4.

I wrote a small script to create 5 million rows of data in a four-column table. These are the create table statements used in MySQL and PGSQL:

- InnoDB

CREATE TABLE sample_innodb (
id integer unsigned not null,
vc1 varchar(200) not null,
vc2 varchar(200) not null,
vc3 varchar(200) not null
) ENGINE=InnoDB;

- MyISAM

CREATE TABLE sample_isam (
id integer unsigned not null,
vc1 varchar(200) not null,
vc2 varchar(200) not null,
vc3 varchar(200) not null
) ENGINE=MyISAM;

- PostgreSQL

create table sample_pgsql (
id integer not null,
vc1 varchar(200) not null,
vc2 varchar(200) not null,
vc3 varchar(200) not null
);

This is the script that I used to create data for these tables:

var chars = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXTZabcdefghiklmnopqrstuvwxyz'.split('');

function randomString(length) {
 var str = '';
 for (var i = 0; i < length; i++) {
    str += chars[Math.floor(Math.random() * chars.length)];
 }

   return str;
}

function genrow(idv, vcv1, vcv2, vcv3) {
 return idv + "," + vcv1 + "," + vcv2 + "," + vcv3;
}

function gentable(numrows) {
 for (var i = 0; i < numrows; i++) {
    var row = 
        genrow(i,
               randomString(10),
               randomString(20),
               randomString(30));

    WScript.Echo(row);
  }
}

gentable(5000000);

I ran this script on Windows using the command:

cscript.exe /nologo test.js > data.csv

You can load this data into MySQL with the following commands:

LOAD DATA LOCAL INFILE 'data.csv'
INTO TABLE sample_innodb
FIELDS TERMINATED BY ','
LINES TERMINATED BY '\n'
(id, vc1, vc2, vc3);

LOAD DATA LOCAL INFILE 'data.csv'
INTO TABLE sample_isam
FIELDS TERMINATED BY ','
LINES TERMINATED BY '\n'
(id, vc1, vc2, vc3);

You can load data into PGSQL with this command:

copy sample_pgsql (id, vc1, vc2, vc3) from 'data.csv' with delimiter ','

I used this query for synchronization to try to apply the worst case table scan script:

MySQL
select count(*) from [table] 
where vc1 like '%blah0%' and vc2 like '%blah1%' and vc3 like '%blah2%';
PostgreSQL
select count(*) from [table] 
where vc1 ilike '%blah0%' and vc2 ilike '%blah1%' and vc3 ilike '%blah2%';

I ran this query several times to get the average time to complete, leaving from the first run so that everything loads into memory.

The results were as follows:

  • InnoDB - 8.56s
  • MyISAM - 1.84s
  • PGSQL - 8.4s

Question

, InnoDB MyISAM , ? - MySQL? MySQL , ", ".

, , , .

, MySQL PGSQL:

MYSQL CONFIG

[client]
port=3306

[mysql]
default-character-set=utf8

[mysqld]
port=3306
basedir="C:/Program Files/MySQL/MySQL Server 5.0/"
datadir="C:/Program Files/MySQL/MySQL Server 5.0/Data/"
default-character-set=utf8
default-storage-engine=INNODB
log="c:/logs/mysql/mysqld.log"
sql-mode="STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION"
max_connections=700
query_cache_size=0M
table_cache=1400
tmp_table_size=16M
thread_cache_size=34

myisam_max_sort_file_size=100G
myisam_sort_buffer_size=8M
key_buffer_size=200M
read_buffer_size=64K
read_rnd_buffer_size=256K
sort_buffer_size=208K

innodb_additional_mem_pool_size=2M
innodb_flush_log_at_trx_commit=1
innodb_log_buffer_size=1M
innodb_buffer_pool_size=200M
innodb_log_file_size=18M
innodb_thread_concurrency=10

PGSQL CONFIG

listen_addresses = '*'        # what IP address(es) to listen on;
                # comma-separated list of addresses;
                # defaults to 'localhost', '*' = all
                # (change requires restart)
port = 5432                # (change requires restart)
max_connections = 100            # (change requires restart)

shared_buffers = 32MB            # min 128kB
                # (change requires restart)
temp_buffers = 12MB            # min 800kB
maintenance_work_mem = 32MB        # min 1MB

log_destination = 'stderr'        # Valid values are combinations of
                # stderr, csvlog, syslog and eventlog,
                # depending on platform.  csvlog
                # requires logging_collector to be on.

logging_collector = on        # Enable capturing of stderr and csvlog
                # into log files. Required to be on for
                # csvlogs.
                # (change requires restart)

log_line_prefix = '%t'            # special values:
                #   %u = user name
                #   %d = database name
                #   %r = remote host and port
                #   %h = remote host
                #   %p = process ID
                #   %t = timestamp without milliseconds
                #   %m = timestamp with milliseconds
                #   %i = command tag
                #   %c = session ID
                #   %l = session line number
                #   %s = session start timestamp
                #   %v = virtual transaction ID
                #   %x = transaction ID (0 if none)
                #   %q = stop here in non-session
                #        processes
                #   %% = '%'
                # e.g. '<%u%%%d> '

datestyle = 'iso, mdy'
lc_messages = 'English_United States.1252'            # locale for system error message
                # strings
lc_monetary = 'English_United States.1252'            # locale for monetary formatting
lc_numeric = 'English_United States.1252'            # locale for number formatting
lc_time = 'English_United States.1252'                # locale for time formatting

default_text_search_config = 'pg_catalog.english'

, , MySQL, \G , :

*************************** 1. row ***************************
           Name: sample_innodb
         Engine: InnoDB
        Version: 10
     Row_format: Compact
           Rows: 5000205
 Avg_row_length: 100
    Data_length: 500154368
Max_data_length: 0
   Index_length: 149700608
      Data_free: 0
 Auto_increment: NULL
    Create_time: 2010-02-02 17:27:50
    Update_time: NULL
     Check_time: NULL
      Collation: utf8_general_ci
       Checksum: NULL
 Create_options:
        Comment: InnoDB free: 497664 kB

*************************** 2. row ***************************
           Name: sample_isam
         Engine: MyISAM
        Version: 10
     Row_format: Dynamic
           Rows: 5000000
 Avg_row_length: 72
    Data_length: 360006508
Max_data_length: 281474976710655
   Index_length: 1024
      Data_free: 0
 Auto_increment: NULL
    Create_time: 2010-02-02 17:27:50
    Update_time: 2010-02-02 17:37:23
     Check_time: NULL
      Collation: utf8_general_ci
       Checksum: NULL
 Create_options:
        Comment:
+5
1

:

  • InnoDB: 5.71s
  • MyISAM: 2.50s

, .

InnoDB :

innodb_buffer_pool_size

  • InnoDB. 70-80% , MySQL InnoDB.
  • innodb_buffer_pool_size 2G ( ) InnoDB 4.60s

id

  • InnoDB PRIMARY KEY. , InnoDB . (id) , .
  • PRIMARY KEY InnoDB 3.80s

MySQL/InnoDB

MySQL 5.1+ MySQL . , InnoDB.

InnoDB , .

:

  • MySQL 5.1.38, InnoDB MySQL
  • MySQL 5.1.43, InnoDB , MySQL
+8

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