Hash Multi-Join

Hash Multi-Join resides in L1/benchmarks/hash_multi_join directory. This benchmark tests the performance of hashMultiJoin primitive with the following query.

SELECT
       SUM(l_extendedprice * (1 - l_discount)) as revenue
FROM
       Orders,
       Lineitem
WHERE
       l_orderkey = o_orderkey
;

Here Orders is a self-made table filled with random data,which contains a column named o_orderkey;

Lineitem is also a table, which contains 3 columns named l_orderkey, l_extendedprice and l_discount.

Dataset

This project uses 32-bit data for numeric fields. To benchmark 64-bit performance, edit host/table_dt.h and make TPCH_INT an int64_t.

Executable Usage

• Work Directory(Step 1)

The steps for library download and environment setup can be found in Vitis Database Library. For getting the design,

cd L1/benchmarks/hash_multi_join

• Build kernel(Step 2)

Run the following make command to build your XCLBIN and host binary targeting a specific device. Please be noticed that this process will take a long time, maybe couple of hours.

make run TARGET=hw DEVICE=xilinx_u280_xdma_201920_3 HOST_ARCH=x86

• Run kernel(Step 3)

To get the benchmark results, please run the following command.

./build_dir.hw.xilinx_u280_xdma_201920_3/test_join.exe -xclbin build_dir.hw.xilinx_u280_xdma_201920_3/hash_multi_join.xclbin

Hash Multi-Join Input Arguments:

Usage: test_join.exe -xclbin
       -xclbin:      the kernel name

Note: Default arguments are set in Makefile, you can use other platforms to build and run.

• Example output(Step 4)

------------- Hash-Join Test ----------------
Data integer width is 32.
Host map buffer has been allocated.
Lineitem 6001215 rows
Orders 227597rows
Lineitem table has been read from disk
Orders table has been read from disk
INFO: CPU ref matched 5389889 rows, sum = 2543814013792128
Found Platform
Platform Name: Xilinx
Selected Device xilinx_u280_xdma_201920_3
INFO: Importing build_dir.hw.xilinx_u280_xdma_201920_3/hash_multi_join.xclbin
Loading: 'build_dir.hw.xilinx_u280_xdma_201920_3/hash_multi_join.xclbin'
Kernel has been created
DDR buffers have been mapped/copy-and-mapped
FPGA result 0: 254381401379.2128
Golden result: 254381401379.2128
FPGA execution time of 1 runs: 84605 usec
Average execution per run: 84605 usec
INFO: kernel 0: execution time 76899 usec
Test Pass
---------------------------------------------

Profiling

The hash multi-join design is validated on Alveo U280 board at 200 MHz frequency. The hardware resource utilizations are listed in the following table.

Table 1 Hardware resources for hash multi-join

Name	LUT	BRAM	URAM	DSP
Platform	130582	204	0	4
join_kernel	133390	271	192	99
User Budget	1172138	1812	960	9020
Percentage	11.38%	14.96%	20.00%	1.10%

The performance is shown below.

In above test, table Lineitem has 3 columns and 6001215 rows and Orders does 1 column and 227597 rows. This means that the design takes 76.899ms to process 69.55MB data, so it achieves 0.88GB/s throughput.