When processing large sets of data, out-of-memory errors can occur when the size of an intermediate result exceeds the available memory allocated to the JVM. If you are encountering these errors, you can tune Fetch Size, Result Memory Size, and JVM Arguments connection options to fit your environment:
Reduce Fetch Size to reduce demands on the driver's internal memory. By lowering the maximum number of rows as specified by Fetch Size, you lower the number of rows the driver is required to process before returning data to the application. Thus, you reduce demands on the driver's internal memory, and, in turn, decrease the likelihood of out-of-memory errors.
To tune Result Memory Size, decrease the value specified until results are successfully returned. Intermediate results larger than the specified setting will be written to disk as opposed to held in memory. When configured correctly, this avoids memory limitations by not relying on memory to process larger intermediate results. Be aware that while writing to disk reduces the risk of out-of-memory errors, it also negatively impacts performance. For optimal performance, decrease this value only to a size necessary to avoid errors.
Note: By default, Result Memory Size is set to -1, which sets the maximum size of intermediate results held in memory to a percentage of the max Java heap size. If you received errors using the default configuration, use the max Java heap size divided by 4 as a starting point when tuning this option.
Increase the JVM heap size using the JVM Arguments connection option. By increasing the max Java heap size, you increase the amount of data the driver can accumulate in memory and avoid out-of-memory errors.
See "Fetch Size", "Result Memory Size", and "JVM Arguments" for additional information.
Reduce Fetch Size to reduce demands on the driver's internal memory. By lowering the maximum number of rows as specified by Fetch Size, you lower the number of rows the driver is required to process before returning data to the application. Thus, you reduce demands on the driver's internal memory, and, in turn, decrease the likelihood of out-of-memory errors.