> For the complete documentation index, see [llms.txt](https://mariadb.com/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://mariadb.com/docs/server/reference/product-development/server-development/quality/benchmarks-and-long-running-tests/benchmarks/performance-of-memory-tables.md). # Performance of MEMORY Tables Example of benchmarking the MEMORY table using perl to generate the data and SQL for the benchmark Between MariaDB 5.5.21 and 5.5.22 some work was done on how the hash index for a [MEMORY](/docs/server/server-usage/storage-engines/memory-storage-engine.md) table is created. This results in better performance when inserting rows into a memory table. The following benchmark compares MariaDB 5.5.21 and 5.5.25. Compiled with identical settings on the same machine. The operation was loading 50 million rows into a `MEMORY` table with [LOAD DATA INFILE](/docs/server/reference/sql-statements/data-manipulation/inserting-loading-data/load-data-into-tables-or-index/load-data-infile.md). Two different tables were tested: one with an indexed [INT](/docs/server/reference/data-types/numeric-data-types/int.md) column and one with an indexed [CHAR(20)](/docs/server/reference/data-types/string-data-types/char.md) column. The data files were pre-generated and located on a SSD. In order to make the effect visible, the cpu speed was set to minimum (core I5 @ 800Mhz) #### Result: | Table Type | MariaDB Version | rows per second | Percent | | ---------- | --------------- | --------------- | ------- | | INT | 5.5.21 | 411022 | 100% | | | 5.5.25 | 510016 | 124% | | CHAR(20) | 5.5.21 | 259399 | 100% | | | 5.5.25 | 411535 | 159% | This is how the benchmark was run: ```sql MariaDB [test]> tee 5.5.21.txt MariaDB [test]> set @instance="5.5.21"; MariaDB [test]> source bench.sql ``` The script used to generate the data files: ```perl #!/usr/bin/perl -w $ROWS=50*1024*1024; open F, ">/tmp/hash1.txt" or die; for ($i=0; $i<$ROWS; $i++) { printf F "%d\n", int(rand($ROWS)); } close F or die; open F, ">/tmp/hash2.txt" or die; for ($i=0; $i<$ROWS; $i++) { $s=""; for (1..20) { $s .= chr(ord('a')+int(rand(26))); } print F $s, "\n"; } close F or die; ``` The benchmark SQL script `bench.sql`: ```sql use test; -- need big heap tables set max_heap_table_size=4*1024*1024*1024; -- table to hold test results create table if not exists results ( id serial, operation char(32), opsize bigint unsigned, started datetime, ended datetime, instance char(20) ); -- dummy run with second data file drop table if exists t1; create table t1 (c1 char(20), index (c1)) engine memory; load data infile "/tmp/hash2.txt" into table t1; drop table t1; -- do total of 5 runs for each table -- run #1 create table t1 (c1 int, index (c1)) engine memory; select @t1:=now(); load data infile "/tmp/hash1.txt" into table t1; select @t2:=now(); select @rows:=count(*) from t1; insert into results (operation, opsize, started, ended, instance) values ("load into INT table", @rows, @t1, @t2, @instance); drop table t1; create table t1 (c1 char(20), index (c1)) engine memory; select @t1:=now(); load data infile "/tmp/hash2.txt" into table t1; select @t2:=now(); select @rows:=count(*) from t1; insert into results (operation, opsize, started, ended, instance) values ("load into CHAR(20) table", @rows, @t1, @t2, @instance); drop table t1; -- run #2 create table t1 (c1 int, index (c1)) engine memory; select @t1:=now(); load data infile "/tmp/hash1.txt" into table t1; select @t2:=now(); select @rows:=count(*) from t1; insert into results (operation, opsize, started, ended, instance) values ("load into INT table", @rows, @t1, @t2, @instance); drop table t1; create table t1 (c1 char(20), index (c1)) engine memory; select @t1:=now(); load data infile "/tmp/hash2.txt" into table t1; select @t2:=now(); select @rows:=count(*) from t1; insert into results (operation, opsize, started, ended, instance) values ("load into CHAR(20) table", @rows, @t1, @t2, @instance); drop table t1; -- run #3 create table t1 (c1 int, index (c1)) engine memory; select @t1:=now(); load data infile "/tmp/hash1.txt" into table t1; select @t2:=now(); select @rows:=count(*) from t1; insert into results (operation, opsize, started, ended, instance) values ("load into INT table", @rows, @t1, @t2, @instance); drop table t1; create table t1 (c1 char(20), index (c1)) engine memory; select @t1:=now(); load data infile "/tmp/hash2.txt" into table t1; select @t2:=now(); select @rows:=count(*) from t1; insert into results (operation, opsize, started, ended, instance) values ("load into CHAR(20) table", @rows, @t1, @t2, @instance); drop table t1; -- run #4 create table t1 (c1 int, index (c1)) engine memory; select @t1:=now(); load data infile "/tmp/hash1.txt" into table t1; select @t2:=now(); select @rows:=count(*) from t1; insert into results (operation, opsize, started, ended, instance) values ("load into INT table", @rows, @t1, @t2, @instance); drop table t1; create table t1 (c1 char(20), index (c1)) engine memory; select @t1:=now(); load data infile "/tmp/hash2.txt" into table t1; select @t2:=now(); select @rows:=count(*) from t1; insert into results (operation, opsize, started, ended, instance) values ("load into CHAR(20) table", @rows, @t1, @t2, @instance); drop table t1; -- run #5 create table t1 (c1 int, index (c1)) engine memory; select @t1:=now(); load data infile "/tmp/hash1.txt" into table t1; select @t2:=now(); select @rows:=count(*) from t1; insert into results (operation, opsize, started, ended, instance) values ("load into INT table", @rows, @t1, @t2, @instance); show table status like 't1'; drop table t1; create table t1 (c1 char(20), index (c1)) engine memory; select @t1:=now(); load data infile "/tmp/hash2.txt" into table t1; select @t2:=now(); select @rows:=count(*) from t1; insert into results (operation, opsize, started, ended, instance) values ("load into CHAR(20) table", @rows, @t1, @t2, @instance); show table status like 't1'; drop table t1; -- list all results select operation, instance, unix_timestamp(ended)-unix_timestamp(started) as duration, opsize/(unix_timestamp(ended)-unix_timestamp(started)) as ops_per_sec from results order by operation, instance, started; -- list average results select operation, instance, avg(opsize/(unix_timestamp(ended)-unix_timestamp(started))) as avg_ops_per_sec from results group by operation, instance; ``` *This page is licensed: CC BY-SA / Gnu FDL* {% @marketo/form formId="4316" %}