# NewSQL Databases Assessment: CockroachDB, MariaDB Xpand, and VoltDB
## 5 Experimental Evaluation
### Performance Evaluation with Star Schema Benchmark
#### 5.2.3 SSB Performance Evaluation with SF = 10  
In this subsection, we evaluate the performance of CockroachDB, MariaDB Xpand, and VoltDB by analyzing query execution time and the average consumption of CPU and RAM for each query flight group, increasing the size of data with a scale factor of 10. In Figure 11, VoltDB, once again, manages to be the fastest database due to its in-memory storage, with an increase of 2.06 times compared to SF = 1. The query execution time is faster compared to the other databases, being below the 10 s mark throughout all queries. CockroachDB, by increasing the scale factor 10 times, displays an average increase of 7.47 times. The results in Figure 11 show a similar linear execution time in Figure 8 using SF = 1. Furthermore, CockroachDB manages to have a linear execution time despite the complexity of the queries and the increase in data size. MariaDB Xpand is the database which takes more time to execute the queries, with an increase of 7.97 times compared to SF = 1. In this case, MariaDB Xpand does not show the same performance in the first group of queries Q1 as VoltDB in Figure 8 with SF = 1. In addition, MariaDB Xpand is the database that shows the highest query execution time, with an increase of 1.52 times compared to CockroachDB and 8.1 times compared to VoltDB. Figure 12 shows the results of RAM percentage consumed in the query execution time with SF = 10. CockroachDB demonstrates better results with memory consumption, with an average of only 145 MB. Throughout all queries, CockroachDB displays good memory control through the execution of each query, with group Q4 being the highest group to consume memory, between 170 MB and 305 MB. The remaining queries remained below 225 MB. Figure 10: Results of percentage usage per core with SF = 1. By contrast, VoltDB is the second highest, with a total average memory use of 326 MB. The first query flight group Q1 displays adequate results between 5 MB and 35 MB. The other group of query flights had a higher consumption, between 300 MB and 600 MB, an approximate increase of 9 times the consumption of RAM. MariaDB Xpand is the database with the highest average consumption of memory, having an average consumption of 367 MB. In query groups Q2, Q3, and Q4, the higher the number of aggregations, the higher the consumption of memory, as this database requires greater memory usage when more aggregations are involved. Despite these queries, query group flight Q1 displays lower RAM consumption, since these queries search for data only in small tables, having simpler queries. Figure 13 shows the results of the CPU percentage used in the query execution with SF = 10. CockroachDB is the database with the lowest average CPU use, with 55.3%, while MariaDB Xpand and VoltDB have an additional increase of 1.4 times compared to SF = 1, with 80.5% and 82.6%, respectively. As mentioned before, CockroachDB has sufficient control over its resources, despite the complexity of each query, demonstrating an almost linear percentage of CPU use during the processing time of each query. On the other hand, MariaDB Xpand appears in second place, with an average use of CPU of 80.5%. During the processing time of each query, we noticed that in query flight group Q4, MariaDB Xpand exceeds the 100% scale. It is possible that one or more processes executed at the same time with the query lead to an increase in resources in the virtual machine. Lastly, VoltDB database has the highest CPU usage. We notice a peak of CPU in query Q3.4, having surpassed the scale of 100%, meaning that during this evaluation, the  
Figure 12: Results of memory usage with SF = 10. Figure 13: Results of CPU usage with SF = 10.  
benchmark used one full core of the processor. We suppose that during the execution of this query, VoltDB had more processes in the background, leading to an increase in CPU usage. The remaining queries have an average CPU usage between 60% and 100%, being the database with the most resources used during this experiment.