Test Description
The latest version of Tencent Cloud TCHouse-P encapsulates Greenplum 6.x. Compared to 5.x, it features greatly improved CRUD (i.e., OLTP) capabilities in multiple concurrent scenarios. These improvements include:
1. Upgraded the PostgreSQL kernel to v9.4 and introduced lock optimizations such as fastpath.
2. Provided global deadlock detection.
3. Optimized global transactions.
Greenplum officially uses TPC-B to test the OLTP capabilities of v6.x. Therefore, Tencent Cloud TCHouse-P also uses this benchmark for testing.
Test Environment
Tencent Cloud TCHouse-P offers compute-intensive and storage-intensive models. You can simply distinguish them from each other:
Compute-intensive: The underlying hardware is SSD with strong random read/write capabilities. It is suitable for hot data analysis and scenarios with mixed loads.
Storage-intensive: The underlying hardware is HDD with average random read/write capabilities but large disk capacity. It is suitable for storing and analyzing larger-scale historical data.
In conclusion, TPC-B requires the compute-intensive model. You can choose two nc2.large nodes and purchase them directly on the purchase page.
Test Tool
Use pgbench, the standard tool of PostgreSQL, for testing.
1. If the test environment is CentOS 7.x, you can download the already compiled tool here.
2. For other environments, you can compile PostgreSQL yourself or directly install the binary package. PostgreSQL 9.4 is recommended for better compatibility.
Test Steps
Creating test database
CREATE DATABASE pgbench;
Modifying query optimizer
ALTER DATABASE pgbench SET optimizer = off;
Note:
1. Tencent Cloud TCHouse-P is preconfigured with two query optimizers, GPORCA and Postgres Planner. The former is the default and suitable for complex query parsing, while the latter is required for OLTP queries.
2. This parameter can also be set at the session level. For convenience, it is set directly at the database level; that is, Postgres Planner is used to access this database, while other databases are still accessed via GPORCA.
Initializing test data
./pgbench -i pgbench -s 100 -p 5436 -h {host} -U {user} pgbench
Note:
10 million data records are tested here.
Running test script
./pgbench -h {host} -p 5436 -r -n -c 32 -j 32 -T 120 -P 1 -U {user} pgbench
Optimization
According to Greenplum's official data, v6.x has a peak TPS of about 5,000 in an ideal environment. You can modify the following parameters to reach a higher value in real tests in Tencent Cloud TCHouse-P:
Parameter | Value | Description |
log_statement | none | Disables the log output of the master node |
gp_enable_fast_sri | on | Improves the efficiency of a single `INSERT` |
gp_enable_gpperfmon | off | Disables monitoring sampling |
Note:
1. In addition to the above configuration, you also need to disable the standby master node for optimal performance.
2. The above configuration is mainly used to test the extreme performance of Tencent Cloud TCHouse-P. Therefore, the above modifications are not recommended in actual production environments.
3. As the configuration modification feature is not available in Tencent Cloud TCHouse-P yet, you can contact us if you need it. You need to restart the cluster after the modification.
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