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https://github.com/fedomn/sqlrs

sqlrs is an in-process sql query engine
https://github.com/fedomn/sqlrs

embedded-database olap query-engine rust sql

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sqlrs is an in-process sql query engine

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# sqlrs



sqlrs is an in-process sql query engine modeled off [duckdb](https://github.com/duckdb/duckdb) in Rust



- The goal of this project is to build a embedded in-process sql query engine for OLAP workloads.

- It leverages the power of Rust ecosystem and Apache Arrow.

- It achieved columnar-vectorized execution engine.

- It will support pipeline parallelism execution in the future.



🚧 The project is actively developing a new planner V2 that inspired by DuckDB, and will replace the planner v1 in the future.🚧 



# SQL demo



currently, the following SQL statements are supported, execute the commands into interactive mode to test them:



- `make run`: run sqlrs in planner_v1

- `make run_v2`: run sqlrs in planner_v2



```sql

-- supported in Roadmap 0.1 (planner_v1)

select first_name from employee where last_name = 'Hopkins';



-- supported in Roadmap 0.2 (planner_v1)

select sum(salary+1), count(salary), max(salary) from employee where id > 1;

select state, count(state), sum(salary) from employee group by state;

-- load csv table

\load csv department ./tests/csv/department.csv

\load csv employee ./tests/csv/employee.csv

-- show tables

\dt



-- supported in Roadmap 0.3 (planner_v1)

select id from employee order by id desc offset 2 limit 1;

select * from employee left join state on employee.state=state.state_code and state.state_name!='California State';



-- supported in Roadmap 0.4 (planner_v1)

-- explain plan tree

\explain select a from t1;

-- Heuristic Optimizer that includes rules such as: Column pruning, Predicates pushdown, Limit pushdown etc.



-- supported in Roadmap 0.5 (planner_v1)

-- distinct

select distinct state from employee;

select count(distinct(b)) from t2;

-- alias

select a as c1 from t1 order by c1 desc limit 1;

select t.a from t1 t where t.b > 1 order by t.a desc limit 1;

-- uncorrelated scalar subquery

select t.* from (select * from t1 where a > 1) t where t.b > 7;

select a, (select max(b) from t1) max_b from t1;



-- supported in Roadmap 0.6 (planner_v2)

-- create and insert table in memory

create table t1(v1 int, v2 int, v3 int);

create table t2 as select * from read_csv('t2.csv');

insert into t1 values (0, 4, 1), (1, 5, 2);

select * from t1;

-- select only expressions

select 1, 2.3, '😇', true, null;

-- pragma commands

show tables;

describe t1;

-- previous SQL statements

select v1+1 as a from t1 where a >= 2;

select v1 from t1 limit 2 offset 1;

-- table functions

select * from sqlrs_tables();

select * from sqlrs_columns();

select * from read_csv('t1.csv');

select * from read_csv('t1.csv', header=>true, delim=>',');

select * from 't1.csv';

-- copy

copy t1 from 't1.csv' ( DELIMITER '|', HEADER false);

-- date and interval

select date '1998-12-01' - interval '1' month;

select interval '1' year + date '1998-12-01';

```



# Roadmap



High level description:



- Roadmap 0.1: Build a basic SQL query on CSV storage

- Roadmap 0.2: Support aggregation operators, e2e testing framework and interactive mode

- Roadmap 0.3: Support limit, order, and join operators

- Roadmap 0.4: Introduce a Heuristic Optimizer and common optimization rules

- Roadmap 0.5: Support distinct, alias, and uncorrelated scalar subquery

- Roadmap 0.6: New planner_v2 highly inspired by DuckDB



Please see [Roadmap](https://github.com/Fedomn/sqlrs/issues?q=roadmap) for more information of implementation steps



# Deep Dive Series Blog (in Chinese)



- On my [blog](https://frankma.me/categories/sqlrs/)

- On [zhihu](https://www.zhihu.com/column/c_1554474699211628544)