Implementing Tarantool aggregation queries using Java
To implement aggregate queries for Tarantool using Java, you first need to add dependencies for the Tarantool Java client in the Maven project. You can add the following Maven coordinates in the 'pom. xml' file:
<dependency>
<groupId>org.tarantool</groupId>
<artifactId>tarantool-java</artifactId>
<version>3.0.11</version>
</dependency>
Once the dependencies of the Tarantool client are added, various aggregation queries can be executed using Java code. Here are some common examples of aggregation queries.
##Count
To calculate the number of records that match specific criteria, the following code can be used:
TarantoolClient client = new TarantoolClientImpl("localhost", 3301);
TarantoolSpaceOperations operations = new DefaultTarantoolSpaceOperations(client);
List<?> result = operations.select("space_name", Collections.emptyList(), 0, 100, 0, Iterator.EQ);
int count = result.size();
System.out.println("Count: " + count);
##Summation
To sum a field, you can use the following code:
TarantoolClient client = new TarantoolClientImpl("localhost", 3301);
TarantoolSpaceOperations operations = new DefaultTarantoolSpaceOperations(client);
List<?> result = operations.select("space_name", Arrays.asList("field_name"), 0, 100, 0, Iterator.ALL);
int sum = 0;
for (Object item : result) {
sum += (Integer) item;
}
System.out.println("Sum: " + sum);
##Average
To calculate the average value of a field, you can use the following code:
TarantoolClient client = new TarantoolClientImpl("localhost", 3301);
TarantoolSpaceOperations operations = new DefaultTarantoolSpaceOperations(client);
List<?> result = operations.select("space_name", Arrays.asList("field_name"), 0, 100, 0, Iterator.ALL);
int sum = 0;
for (Object item : result) {
sum += (Integer) item;
}
double average = sum / (double) result.size();
System.out.println("Average: " + average);
##Maximum and minimum values
To find the maximum and minimum values of a field, the following code can be used:
TarantoolClient client = new TarantoolClientImpl("localhost", 3301);
TarantoolSpaceOperations operations = new DefaultTarantoolSpaceOperations(client);
List<?> result = operations.select("space_name", Arrays.asList("field_name"), 0, 100, 0, Iterator.ALL);
int max = Integer.MIN_VALUE;
int min = Integer.MAX_VALUE;
for (Object item : result) {
int value = (Integer) item;
if (value > max) {
max = value;
}
if (value < min) {
min = value;
}
}
System.out.println("Max: " + max);
System.out.println("Min: " + min);
These sample codes demonstrate how to implement aggregate queries in Tarantool using Java. Please note that the 'spacename' and 'fieldname' in the above example need to be replaced with the actual space and field names used.
