Query Execution

Vectorized Model

AresDB works with vector batches that are efficiently processed in parallel using the Thrust library.

Parallel Execution

Intra-Operator (Horizontal)

Executes queries with the one operation per kernel (OOPK) model.

Storage Model

Decomposition Storage Model (Columnar)

Storage Organization

Sorted Files

Archived data is sorted in a user specified column order, and files are organized by UTC day and Unix time cutoffs.

Compression

Run-Length Encoding

Only compresses data with user defined sort orders that are low cardinality.

Joins

Hash Join

Supports hash joins from fact tables (finite set data such as cities) to dimension tables (infinite streaming data such as rides). Also supports geospatial joins (i.e. geographically bounded area overlap) and normal foreign key joins. Note that AresDB uses late materialization for its joins, meaning the join may not be executed until a foreign key is accessed.

Indexes

Hash Table

Used mainly for primary key deduplication.

System Architecture

Shared-Disk

The CPU is only used to load information from storage into CPU memory and to distribute this data to GPU memory. The database system delegates each operator in a query to some GPU, so it's able to handle multiple GPUs by delegating different operations to different GPUs, each of which have completely separate memory. There are plans to implement proper distributed designs, but currently we're limited to a single system with multiple GPUs.

Logging

Logical Logging

Log files contain description of database upserts which must be replayed to rebuild the database after a crash.

Data Model

Relational

Query Interface

Custom API

Uses a proprietary execution language called Ares Query Language (AQL) which is based in the JSON format, making it compatible with any language that can handle files and/or JSON.

Query Compilation

Not Supported

Checkpoints

Fuzzy

Snapshots are triggered by either a certain number of mutations or a certain time frame specific to each table.

Stored Procedures

Not Supported

Hardware Acceleration

GPU

Uses GPUs for query execution

Storage Architecture

Hybrid

Data within the archival delay of a table is kept uncompressed in live batches, while everything else is stored in compressed archival batches. If new data is ingested that is outside the archival array, it's added to an archival backfill queue which will be inserted into the archived batches asynchronously.

Views

Materialized Views

AresDB uses late materialization for its joins, meaning that it may only physically execute the join once a foreign key is accessed.

Foreign Keys

Supported

AresDB supports foreign key joins.