1. Release Notes

The following are the release notes for HammerDB v4.2.

1.1. Nomenclature Change

From version 4.0 In the database.xml file and the User Interface the workload names have changed to TPROC-C and TPROC-H. This is a nomenclature change only to represent that the workloads are fair use implementations derived from the TPC specifications and the nomenclature does not change the functionality of the workload compared to prior versions using the TPC-C and TPC-H terminology.

1.2. Stored Procedure Refactoring and Performance

From version 4.0 the stored procedures for the Oracle and PostgreSQL TPROC-C workloads have been refactored. This increases the expected performance between versions and consequently the performance from HammerDB v4.0 cannot be compared directly to the performance of v3.3 or previous releases. Additionally for some workloads HammerDB v4.0 changed the relationship between the NOPM and TPM metrics compared to previous versions. As a result of the stored procedure refactoring using bulk operations more work is processed per commit and therefore in these cases the NOPM has increased whilst the TPM remains the same. This indicates a real measure of increased throughput by doing more work per database transaction and consequently NOPM is now listed first as the primary metric in reporting output. However as raised in HammerDB GitHub Issue #111 there may be cases where there is a dependency on the wording of the HammerDB log. For this reason a configuration option in the generic.xml file of first_result is given. If this option is set to NOPM then the v4.0 format is used if set to TPM then the output is compatible with v3.3.


1.3. MariaDB added as database separate from MySQL

Prior to version 4.2 MariaDB was supported using the MySQL workload, this required the separate installation of the MySQL 8.0 client. From version 4.2 MariaDB has been added as a separate database using the MariaDB client meaning no separate installation is required. At version 4.2 the MariaDB workload implementation is the same as the MySQL workload, however these are expected to diverge over time by taking advantage of different database features.

1.4. Increase of TPROC-C Schema Size Limits to 100,000 warehouses

From version 4.2 the TPROC-C Schema Size Limits have been increased from 5,000 for the GUI/CLI schema build and 30,000 for the datagen feature to 100,000 for both enabling the building of larger schemas. This enables the testing of larger scaled workload scenarios however it is recommended to read the documentation carefully to prevent over-provisioning of the schema for the intended test and system.

1.5. Known Third-Party Driver Issues

HammerDB has a dependency on 3rd party driver libraries to connect to the target databases. The following are known issues with some of the 3rd party drivers that HammerDB uses.

1.5.1. Oracle on Windows: Oracle Bug 12733000 OCIStmtRelease crashes or hangs if called after freeing the service context handle

If you are running HammerDB against Oracle on Windows there is long established bug in Oracle that can cause application crashes for multi-threaded applications on Windows.This bug can be investigated on the My Oracle Support website with the following reference. Bug 12733000 OCIStmtRelease crashes or hangs if called after freeing the service context handle. To resolve this Oracle issue add the following entry to the SQLNET.ORA file on your HammerDB client.


1.5.2. SQL Server on Linux: unixODBC's handle validation may become a performance bottleneck

Using the HammerDB client for SQL Server on Linux can be slower than the same client on Windows when using the default installed unixODBC drivers on many Linux distributions. As described in the SQL Server Programming Guidelines "When using the driver with highly multithreaded applications, unixODBC's handle validation may become a performance bottleneck. In such scenarios, significantly more performance may be obtained by compiling unixODBC with the --enable-fastvalidate option. However, beware that this may cause applications which pass invalid handles to ODBC APIs to crash instead of returning SQL_INVALID_HANDLE errors." Recompiling unixODBC with the --enable-fastvalidate option has been measured to improve client performance by 2X. Example configure options used to build unixODBC are shown as follows:

./configure --prefix=/usr/local/unixODBC --enable-gui=no --enable-drivers=no --enable-iconv 
--with-iconv-char-enc=UTF8 --with-iconv-ucode-enc=UTF16LE --enable-threads=yes --enable-fastvalidate

1.6. Linux Font Pre-Installation Requirements

On Linux HammerDB requires the Xft FreeType-based font drawing library for X installed as follows:


$ sudo apt-get install libxft-dev

Red Hat:

$ yum install libXft