Resql Database System and Flounder Library (Prototypes)

Authors: Henning Funke <henning.funke@cs.tu-dortmund.de>
         Jan Mühlig <jan.muehlig@tu-dortmund.de>

Query compilation-based database system with low compilation times.

Research
  ReSQL and Flounder are used as prototype systems for database 
  research. This research includes the following publications:
   
  Funke, Henning, Jan Mühlig, and Jens Teubner. "Low-latency query 
  compilation." The VLDB Journal (2022).

  Funke, Henning, and Jens Teubner. "Low-latency compilation of SQL 
  queries to machine code." Proceedings of the VLDB Endowment (2021).

  Funke, Henning, Jan Mühlig, and Jens Teubner. "Efficient 
  generation of machine code for query compilers." DaMoN (2020).

Build
  First make sure that the libraries and tools are available.  
  Then use 'make' in this folder. Developed and tested under 
  Ubuntu 18.04. For debug builds use 'make DEBUG=1'. To run 
  tests use 'make run-tests'.

Libraries
  flex           needs to be installed, e.g. via apt
  libreadline    needs to be installed, e.g. via apt
  asmjit         source included, build with cmake in lib/asmjit
  lemon          source included, no build necessary
  cereal         source included, no build necessary
  cxxopts        source included, no build necessary

Other tools
  nasm           assembler
  clang          c++ compiler

Run
  ReSQL runs either in interactive or client/server mode. Use './resql -h'
  for instructions. If the file startup.sql exists in this folder, ReSQL 
  will execute it at the start of the server (or standalone). A startup 
  file with the following commands, for example, will load a sample 
  database (10 MB).

    showplan=true;
    exec tpch/create.sql;
    exec tpch/load_sf001.sql;

Commands
  showfln=true   show Flounder IR
  showasm=true   show machine assembly
  showperf=true  show performance measurements
  tables         show tables from current database
  emitmc=true    assemble via asmjit
  emitmc=false   assemble via nasm
  threads=4      use 4 threads for execution
  tofile=true    write query results to file
                 qres.tbl (server)
  exec file.sql  execute file with SQL statements 
                 separated by ';'
  select *       execute SQL
  q or exit      quit

 
ReSQL understands the following commands (for example)
  create table name ( name1 type1, name2 type2 )
  bulk insert name from "path/foo.tbl" with ( fieldterminator="|" )
  select c,avg(d*a) from foo,bar where a=d group by c order by c

Known Issues
  - Memory for Expr ist not freed.