Hi Adrian, Could you share your state backend configuration ? Regards, Maciek
pt., 9 lip 2021 o 19:09 Adrian Bednarz <adrianbedn...@gmail.com> napisał(a): > > Hello, > > We are experimenting with lookup joins in Flink 1.13.0. Unfortunately, we > unexpectedly hit significant performance degradation when changing the state > backend to RocksDB. > > We performed tests with two tables: fact table TXN and dimension table > CUSTOMER with the following schemas: > > TXN: > |-- PROD_ID: BIGINT > |-- CUST_ID: BIGINT > |-- TYPE: BIGINT > |-- AMOUNT: BIGINT > |-- ITEMS: BIGINT > |-- TS: TIMESTAMP(3) **rowtime** > |-- WATERMARK FOR TS: TIMESTAMP(3) AS `R` - INTERVAL '0' SECONDS > > CUSTOMER: > |-- ID: BIGINT > |-- STATE: BIGINT > |-- AGE: BIGINT > |-- SCORE: DOUBLE > |-- PRIMARY KEY: ID > > And the following query: > select state, sum(amount) from txn t JOIN customer FOR SYSTEM_TIME AS OF t.ts > ON t.cust_id = customer.id group by state, TUMBLE(t.ts, INTERVAL '1' SECOND) > > In our catalog, we reconfigured the customer table so that the watermark is > set to infinity on that side of the join. We generate data in a round robin > fashion (except for timestamp that grows with a step of 1 ms). > > We performed our experiments on a single c5.4xlarge machine with heap and > managed memory size set to 12gb with a blackhole sink. With 2 000 000 fact > records and 100 000 dimension records, a job with heap backend finishes in 5 > seconds whereas RocksDB executes in 1h 24m. For 400 000 dimension records it > doesn't grow significantly but goes up to 1h 36m (the job processes more > records after all). > > We also checked what would happen if we reduced the amount of customer ids to > 1. Our expectation was that RocksDB will not offload anything to disk anymore > so the performance should be comparable with heap backend. It was executed in > 10 minutes. > > Is this something anybody experienced or something to be expected? Of course, > we assumed RocksDB to perform slower but 300 eps is below our expectations. > > Thanks, > Adrian -- Maciek Bryński
