page size in Ignite Sql query

Question

I am trying create a sql query on ignite to fetch records in batches. I found in ignite docs that there is a way to set page size. I would like to know if this parameter is query result payload size or number of records returned at a time.

https://ignite.apache.org/releases/latest/javadoc/org/apache/ignite/cache/query/SqlFieldsQuery.html#setPageSize-int-

Also, is page size applicable only when we obtain query cursor? Is it used when we do query.getAll() ?

private static final String EMP_CACHE = "emp_cache";

  public static void main(String[] args) {

    try (Ignite ignite = Ignition.start(new IgniteConfiguration())) {
      IgniteCache<Long, Employee> empCache = ignite.getOrCreateCache(empCacheConfig());
      String[] dept = {"Math", "Science", "CS", "ECE", "Physics", "Chemistry", "English", "Hindi"};
      long count = 10;
      while (count-- > 0) {
        String name = RandomStringUtils.randomAlphanumeric(20);
        int deptNo = (int) (Math.random() * 7);
        empCache.put(count, new Employee(count, name, dept[deptNo]));
      }
      FieldsQueryCursor<List<?>> cursor =
          empCache.query(new SqlFieldsQuery("select * from empCache.EMPLOYEE").setPageSize(2));
      for (List<?> objects : cursor) {
        System.out.println("Record =" + objects);
        // would this mean cursor will fetch two records and go back to ignite to fetch next batch
        // OR cursor will fetch records 2KB at a time
      }
    }
  }

  public static CacheConfiguration<Long, Employee> empCacheConfig() {
    CacheConfiguration<Long, Employee> empCacheConfig = new CacheConfiguration<>(EMP_CACHE);
    empCacheConfig.setCacheMode(CacheMode.PARTITIONED);
    empCacheConfig.setBackups(1);
    empCacheConfig.setIndexedTypes(Long.class, Employee.class);
    return empCacheConfig;
  }

Thanks.

Answer 1

1. pageSize sets the number of rows per batch (not bytes). Rows are transferred in batches from remote nodes.

2. getAll is not affected by this property