Struct tpch_bench::query_6::tables::LineItem

pub struct LineItem {
    pub shipdate: DerefMem<i32>,
    pub discount: DerefMem<i32>,
    pub quantity: DerefMem<i32>,
    pub extendedprice: DerefMem<i32>,
}

A columnar LineItem table for Query 6.

The table contains only those attributes used in Query 6.

The number of rows in LineItem is specified based on the Orders table. For each row in orders, there are between [1, 7] rows in LineItem. To avoid generating a Orders table, the length of LineItem is calculated based on the Central Limit Theorem. The CLM says that the sum of N variables has a normal distribution with mean = 4 * N and variance = 3, because a uniform distribution between [1, 7] has mean = 4 and variance = 3. N is specified as scale_factor * 1’500’000.

Fields

shipdate: DerefMem<i32>

l_shipdate

The date is encoded as the number of days starting from 1992-01-01.

The shipdate is based on o_orderdate. o_orderdate is sampled from dates between 1992-01-01 and 1998-12-31, minus 151 days. This range includes 2557-151 = 2406 days, whereby 1992 and 1996 are leap years. The shipdate then includes a random number of days between [0, 121] added onto the orderdate.

Overall, to sample a shipdate, the orderdate is uniformly sampled from [0, 2406] and the a uniformly sampled value between [0, 121] is added on top.

discount: DerefMem<i32>

l_discount

The discount is specified as a fixed-point decimal value between [0.00, 0.10]. It is encoded as percent, i.e., times 100.

quantity: DerefMem<i32>

l_quantity

The quantity is specified as a random integer value between [1, 50].

extendedprice: DerefMem<i32>

l_extendedprice

The exact value of extendedprice has no impact on measuring Query 6. Thus, it is sampled as a random integer between [1, MAX_INT].

Implementations

impl LineItem

pub fn new(scale_factor: u32, mem_type: DerefMemType) -> Result<LineItem>

pub fn len(&self) -> usize