MySQL vs. PostgreSQL
2006-08-17 16:52
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MySQL vs. PostgreSQL
Author: Maciej Glowiak / PSNC, Last update 25 October 2005[edit]
Comparison
The comparsion of the newest, stable and production version of PostgreSQL 8.0 and MySQL 4.1 (MySQL has also development version 5.0).| PostgreSQL 8.0 | MySQL 4.1 | MySQL 5.0 (beta) | |
| Operating System | Windows, more than 2 dozen Unix-like operating systems (Linux, all BSDs, HP-UX, AIX, OS X, Unixware, Netware...) | Linux, Windows, FreeBSD, MacOS X, Solaris, HP UX, AIX, and other See: Full list | Linux, Windows, FreeBSD, MacOS X, Solaris, HP UX, AIX, and other See: Full list |
| ANSI SQL compliance | ANSI-SQL 92/99 | Follows some of the ANSI SQL standards; can be run in ANSI mode | Possible; user can run MySQL in more ANSI compatible (ANSI mode) |
| Performance | Slower | Faster | untested |
| Sub-selects | Yes | Yes since 4.1 | Yes |
| Transactions | Yes | Yes InnoDB tables only | Yes |
| Database replication | Yes | Yes | Yes |
| Foreign key support | Yes | Yes InnoDB tables only | Yes |
| Views | Yes | No | Yes |
| Stored procedures | Yes (pl/SQL) | No | Yes (procedural) |
| Triggers | Yes | No | Yes |
| Unions | Yes | Yes since 4.0 | Yes |
| Full joins | Yes | No | No planned for 5.1 |
| Constraints | Yes | No | No Planned for 5.1 |
| Cursors | Yes | No | Partial (read only) |
| Procedural languages (PLs) | Yes PL/pgSQL, PL/Tcl, PL/Perl, PL/Python PL/PHP, PL/Java or user defined | No | Yes Supports stored procedures (persistent modules) languages as defined by ANSI SQL 2003 |
| Vacuum (cleanup) | Yes | Yes by OPTIMIZE TABLE | Yes by OPTIMIZE TABLE |
| Different table types | No (PostgreSQL has its own inbuilt table types and doesn't use any alternative ones) | Yes MyISAM, InnoDB, MEMORY, BerkeleyDB, MERGE, Archive and NDB (Cluster) (InnoDB has additional functionality) Read additional notes | Yes MyISAM, InnoDB, MEMORY, BerkeleyDB, MERGE, Archive and NDB (Cluster), Federated (InnoDB has additional functionality) Read additional notes |
| ODBC | Yes | Yes | Yes |
| JDBC | Yes | Yes | Yes |
| Other APIs | Most of languages (i.e. Perl, C/C++, .NET, OLE-DB, Tcl/Tk, Python, PHP, ...) | Most of languages | Most of languages |
| IPv6 s 4000 upport | Yes | No Does it support IPv6? "At the moment not intentionally, but they might work on IPv6 environment." | No Planning in 5.1 |
| WWW | - Homepage, - Manual, - Features | - Homepage, - Manual, - Features | - Homepage, - Manual, - Features, - What's new in 5.0, - Roadmap-what's new in 5.1 |
| Installation | PostgreSQL installation | MySQL installation | |
| Download | Download page | Download page |
More details and test results below Table-of-content:
edit]
Additional notes
[edit]MySQL table types
(From: Josh Chamas, MySQL):Note that MyISAM, and other engines, have much functionality that is independent from the rest.
MyISAM supports full text indexing, OpenGIS RTREE's, and copying tables at the file i/o level.
InnoDB supports row level locking, MVCC, foreign keys, and hot backup.
NDB aka MySQL Cluster supports HASH and BTREE indexes, but is primarily used for its high availability shared-nothing architecture.
ARCHIVE supports zlib compression of row data, and only INSERT/SELECT so can be assured the data has not been tampered with
MEMORY has no disk storage footprint, very nice for global temporary tables, and support BTREE and HASH indexes
Gemini used to be supported in older versions
More about different table types supported by MySQL can be found on http://www.developer.com/db/article.php/2235521 .
[edit]
Sources
Based on Side-by-side comparison of some of the more frequently used features of MySQL and PostgreSQL article,MySQL roadmap,
Open source database software comparsion
MySQL manual,
PostgreSQL manual
[edit]
More detailed comparsions
If you want to compare more databases please visit:The database server feature comparisons on MySQL page.
Comparsion of mysql, pgsql and other databases
[edit]
Installation
Information about installation of:MySQL installation
PostgreSQL installation
[edit]
Summary for JRA1
MySQL is simplier than PostgreSQL but can be much faster. MySQL doesn't support many advanced features that may be important in huge relational and complicated databases. But for JRA1 measurement architecture MySQL should be adequate (we probably wouldn't use the most advanced features).[edit]
Benchmark
I made a simple benchmark using JDBC connectors. I used default JDBC libraries taken from home sites of MySQL and PostgreSQL.[edit]
Disclaimer
The previous test wf349
as performed only for GEANT2 JRA1 development. We just wanted to know which database works faster - MySQL or Postgres. I used the default configuration.
After the first article I got a lot of comments. Many people pointed that I had compared default MySQL MyISAM tables with more advanced PostgreSQL tables. I decided to test MySQL InnoDB (which are more advanced, but slower than MyISAM).
I am still using the default configuration. That's right - both databases could be tuned up and work much faster! If you want to test different configuration, please take my benchmark program. Of course you may send me your results. Your comments are always welcome, but don't ask me to test all configurations, options and so on.
[edit]
Test procedure
The benchmark program:generates a set of source data
connects to databases
creates tables (MyISAM, InnoDB or Postgres tables)
inserts data (from the set generated before, so the data is the same for all tests)
perform SELECT operations
deletes all data from the table
[edit]
Hardware
Computer used in testing was Intel Celeron 2.4 GHz, 512 MB RAM. Communication with databases was local only (localhost).[edit]
Software
Operating system - Slackware 10.1 with Linux 2.6.11.6 kernelDatabases:
PostgreSQL 8.0.1
MySQL 4.1.9 (released in Jan 2005).
JDBC drivers:
mysql-connector-java-3.1.6-bin.jar
postgresql-8.0-310.jdbc3.jar
Java - Java Runtime Environment 1.5.0_02
[edit]
Code
Benchmark code is available here The benchmark source code page.[edit]
Table
The table I created was:CREATE TABLE a ( id INT PRIMARY KEY, number INT NOT NULL, category VARCHAR(10), description VARCHAR(255) );
In MySQL I created tables using TYPE parameter:
CREATE TABLE a ( . . . ) TYPE MyISAM;
and
CREATE TABLE a ( . . . ) TYPE InnoDB;
[edit]
Sample record
id=100005 (primary key)
number=229367 (random value, range 1..1000000)
category=bbb ("aaa" or "bbb")
description=
"347443838512686414057
081510422273660302804
763737435066026818127
227402036010377674002
2531885133461821"
(a 100-random-digit-string)[edit]
Data set
Input data sets for both databases were the same. Only in testing PostgreSQL with fsync=false I had to restart server and the data set was different. The benchmark is really simple one, so it doesn't support saving and restoring data.[edit]
Results
First column contains number of records in the table. Other columns contain approx. times in milliseconds. Time measurement method was System.currentTimeMillis() function in Java.[edit]
INSERT INTO a VALUES ( . . . );
MySQL MySQL PostgreSQL PostgreSQL INSERT MyISAM InnoDB fsync=true fsync=false 5000 3006 34745 17540 4825 10000 4967 71402 14052 8772 15000 7474 103469 21873 13064 20000 9996 143009 110359 17374 25000 12524 170862 101442 21974 30000 15034 186316 51390 26148 35000 17515 119604 49103 30484 40000 20040 58373 158071 35112 45000 21586 262558 65042 39058 50000 23980 68716 73832 43418
X axis - number of records, Y axis - times in ms
[edit]
SELECT * FROM a;
MySQL MySQL PostgreSQL PostgreSQL QUERY1 MyISAM InnoDB fsync=true fsync=false 5000 45 42 108 104 10000 157 174 141 150 15000 110 113 218 219 20000 240 156 429 300 25000 288 303 420 506 30000 352 251 489 614 35000 378 285 721 738 40000 415 316 864 805 45000 479 491 880 737 50000 525 562 1009 868
X axis - number of records, Y axis - times in ms
[edit]
SELECT * FROM a ORDER BY 4;
MySQL MySQL PostgreSQL PostgreSQL QUERY2 MyISAM InnoDB fsync=true fsync=false 5000 101 101 202 218 10000 201 207 415 412 15000 309 307 664 864 20000 436 415 879 897 25000 508 515 1206 1223 30000 617 719 1401 1366 35000 722 840 1763 1671 40000 827 958 1909 1928 45000 998 953 2180 2285 50000 1031 1096 2518 2713
X axis - number of records, Y axis - times in ms
[edit]
DELETE FROM a;
MySQL MySQL PostgreSQL PostgreSQL DELETE MyISAM InnoDB fsync=true fsync=false 5000 1 78 23 19 10000 2 166 56 40 15000 3 259 79 60 20000 3 330 104 82 25000 3 501 216 154 30000 4 405 733 151 35000 4 490 230 241 40000 5 664 341 235 45000 6 753 578 340 50000 6 1171 614 282
X axis - number of records, Y axis - times in ms
[edit]
What are these MyISAM, InnoDB and fsync???
[edit]MySQL (MyISAM and InnoDB)
MyISAM and InnoDB are MySQL table types. The default one is MyISAM which doesn't support more advanced features. About differences between them you can read in Pros and Cons of MySQL Table Types article.[edit]
PostgreSQL (fsync option)
During my first tests I noticed that MySQL is much faster than PostgreSQL (I am talking about default configuration, just after installing the database).Inserting 20 000 records took:
10 seconds in MySQL (MyISAM)
and
167 seconds in PostgreSQL
I read that PostgreSQL did (automatic) COMMIT after each INSERT operation.
It means that if you wanted to insert data into the database e.g:
INSERT a, INSERT b, INSERT c
PostgreSQL would do it like:
INSERT a, COMMIT, INSERT b, COMMIT, INSERT c, COMMIT.
I wanted to try how fast would PostgreSQL work without auto-commiting. I put all INSERT operations in one block:
BEGIN (transaction), INSERT a, INSERT b, INSERT c, COMMIT (end of transaction)
I measured that PostgreSQL needed about 6 milliseconds for each COMMIT (on my computer).
So if you have i.e. 100 INSERT operations, they take 203 ms for PostgreSQL, so (statistically) one such an operation takes 2 ms. If you add COMMIT after each INSERT you get:
100 operations * (2 ms of INSERT + 6 ms of COMMIT) = 100*8 = 800 ms!
The measured result for that was 794 ms! That's the difference.
[edit]
I got a lot of comments to that:
Emmanuel Guyot explained:
You ask what PostgreSQL does while commiting. There is an option (fsync) that ask to flush data each time the commit is done. You can have more information here: PostgreSQL Run-time Configuration at § 16.4.4.1 (or read below)
This is really time consuming but useful in case a power failure occurs.
I think this is the part that misses in your article: How robust are both databases?
I hope this explanation helps you to understand why the commit is so slow and maybe you'll be able to make a new test without this option.
fsync option in PostgreSQL (from PostgreSQL Run-time Configuration § 16.4.4.1)
If this option is on, the PostgreSQL server will use the fsync() system call in several places to make sure that updates are physically written to disk. This insures that a database cluster will recover to a consistent state after an operating system or hardware crash.
However, using fsync() results in a performance penalty: when a transaction is committed, PostgreSQL must wait for the operating system to flush the write-ahead log to disk. When fsync is disabled, the operating system is allowed to do its best in buffering, ordering, and delaying writes. This can result in significantly improved performance. However, if the system crashes, the results of the last few committed transactions may be lost in part or whole. In the worst case, unrecoverable data corruption may occur. (Crashes of the database server itself are not a risk factor here. Only an operating-system-level crash creates a risk of corruption.)
Due to the risks involved, there is no universally correct setting for fsync. Some administrators always disable fsync, while others only turn it off for bulk loads, where there is a clear restart point if something goes wrong, whereas some administrators always leave fsync enabled. The default is to enable fsync, for maximum reliability. If you trust your operating system, your hardware, and your utility company (or your battery backup), you can consider disabling fsync.
[edit]
Links
If you want to get more information about differences between Postgres and MySQL please visit:Pros and Cons of MySQL Table Types
Read the comparsion of mysql, pgsql and other databases
and something about tuning PostgreSQL for performance - "Power PostgreSQL" by J.Berkus and J.Conway.
The side-by-side comparison of some of the more frequently used features of MySQL and PostgreSQL
Professional benchmark between MySQL 3.23 and PostgreSQL 7.1.2 (so both quite old).
[edit]
Manuals
MySQL manual,PostgreSQL manual
[edit]
Download
PostgreSQL download pageMySQL download page
Benchmark source code (in Java) with short installation guide
[edit]
Installation
You will find some installation hints:MySQL installation
PostgreSQL installation
[edit]
Contact
[edit]Author
Please send your comments, suggestions and other to:Maciej Glowiak, PSNC (email address: mac at man.poznan.pl)
Retrieved from "http://monstera.man.poznan.pl/jra1-wiki/index.php/Mysql_vs_postgres"
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