README.md

educkdb

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DuckDB NIF for Erlang.

DuckDB (https://duckdb.org/) is an in-process SQL OLAP database management system. This library makes it possible to use DuckDB in Erlang, Elixir or other languages supported by the beam.

Example

Connect to a database

{ok, Db} = educkdb:open("database.db"),
{ok, Conn} = educkdb:connect(Db)
...

Create a table by reading a CSV or parquet files.

{ok, _} = educkdb:query(Conn, "CREATE TABLE ontime AS SELECT * FROM 'test.csv'"),
{ok, ParquetData} = educkdb:query(Conn, "SELECT * FROM 'test.parquet'"),
...

API

Note: This is a work in progress. At the moment it is possible to open, connect, query and return integer and varchar results. The nif function returning the query result will become a yielding nif. This is important for large query results.

Startup

open(filename, options) -> {ok, DB} | {error, msg}

Note: (dirty scheduler)

connect(db) -> {ok, Conn} | {error, msg}

Note, creates a nif thread with a command queue, all calls which uses the connection as parameter will be send to the thread via the queue.

disconnect(connection) -> ok | {error, msg}

Note: via command thread.

Explicitly disconnect the connection. This also explicitly finalizes the thread. It is not required to call this. The garbage collector will disconnection automatically.

close(db) -> ok | {error, msg}

Note: (dirty scheduler)

Explicitly close the db. It is not required to call this. The garbage collector will disconnection automatically.

Querying

query(Conn, Query) -> {ok, QueryResult} | {error, msg}

Note: dirty scheduler

Run a query, return the result.

Prepared Statements

prepare(Conn, Query) -> {ok, Stmt} | {error, _}

Note: dirty scheduler

bind(Stmt, Values) -> ok | {error, _}

Note: direct c

bind_null(Stmt, Index, Value) -> ok | error

Note: direct c

bind_boolean(Stmt, Index, Value) -> ok | error

Note: direct c

bind_int8(Stmt, Index, Value) -> ok | error

Note: direct c

bind_int16(Stmt, Index, Value) -> ok | error

Note: direct c

bind_int32(Stmt, Index, Value) -> ok | error

Note: direct c

bind_int64(Stmt, Index, Value) -> ok | error

Note: direct c

bind_hugeint(Stmt, Index, Value) -> ok | error

Note: direct c

bind_uint8(Stmt, Index, Value) -> ok | error

Note: direct c

bind_uint16(Stmt, Index, Value) -> ok | error

Note: direct c

bind_uint32(Stmt, Index, Value) -> ok | error

Note: direct c

bind_uint64(Stmt, Index, Value) -> ok | error

Note: direct c

bind_float(Stmt, Index, Value) -> ok | error

Note: direct c

bind_double(Stmt, Index, Value) -> ok | error

Note: direct c

bind_date(Stmt, Index, Value) -> ok | error

Note: direct c

bind_time(Stmt, Index, Value) -> ok | error

Note: direct c

bind_timestamp(Stmt, Index, Value) -> ok | error

Note: direct c

....more

execute_statement(Stmt) -> {ok, result()} | {error, _}

Note: dirty thread

appender

Implementation notes

• https://potatosalad.io/2017/08/05/latency-of-native-functions-for-erlang-and-elixir
• https://github.com/vinoski/bitwise