Pinot Client Rust

---

A rust library to query Apache Pinot.

Installing Pinot

To install Pinot locally, please follow this Pinot Quickstart link to install and start Pinot batch quickstart locally.

bin/quick-start-batch.sh

Alternatively, the docker contained Pinot database ochestrated by this repository's docker-compose.yaml file may be used.

make prepare-pinot

Examples

Check out Client library Github Repo

git clone [email protected]:yougov/pinot-client-rust.git
cd pinot-client-rust

Start up the docker contained pinot database

make prepare-pinot

Build and run an example application to query from Pinot

cargo run --example pql-query
cargo run --example sql-query-deserialize-to-data-row
cargo run --example sql-query-deserialize-to-struct

Usage

Create a Pinot Connection

Pinot client could be initialized through:

1. Zookeeper Path.

let client = pinot_client_rust::connection::client_from_zookeeper(
    &pinot_client_rust::zookeeper::ZookeeperConfig::new(
        vec!["localhost:2181".to_string()],
        "/PinotCluster".to_string(),
    ),
    None
);

2. A list of broker addresses.

let client = pinot_client_rust::connection::client_from_broker_list(
    vec!["localhost:8099".to_string()], None);

Asynchronous Queries

An asynchronous connection can be established with pinot_client_rust::async_connection::AsyncConnection for which exist equivalents to the above described synchronous instantiation methods.

Query Pinot

Please see this example for your reference.

Code snippet:

fn main() {
    let client = pinot_client_rust::connection::client_from_broker_list(
        vec!["localhost:8099".to_string()], None).unwrap();
    let broker_response = client.execute_sql::<pinot_client_rust::response::data::DataRow>(
        "baseballStats",
        "select count(*) as cnt, sum(homeRuns) as sum_homeRuns from baseballStats group by teamID limit 10"
    ).unwrap();
    if let Some(stats) = broker_response.stats {
        log::info!(
            "Query Stats: response time - {} ms, scanned docs - {}, total docs - {}",
            stats.time_used_ms,
            stats.num_docs_scanned,
            stats.total_docs,
        );
    }
}

Response Format

Query Responses are defined by one of two broker response structures. SQL queries return SqlResponse, whose generic parameter is supported by all structs implementing the FromRow trait, whereas PQL queries return PqlResponse. SqlResponse contains a Table, the holder for SQL query data, whereas PqlResponse contains AggregationResults and SelectionResults, the holders for PQL query data. Exceptions for a given request for both SqlResponse and PqlResponse are stored in the Exception array. Stats for a given request for both SqlResponse and PqlResponse are stored in ResponseStats.

Common

Exception is defined as:

/// Pinot exception.
#[derive(Clone, Debug, Deserialize, Eq, PartialEq)]
pub struct PinotException {
    #[serde(rename(deserialize = "errorCode"))]
    pub error_code: i32,
    pub message: String,
}

ResponseStats is defined as:

/// ResponseStats carries all stats returned by a query.
#[derive(Clone, Debug, PartialEq)]
pub struct ResponseStats {
    pub trace_info: HashMap<String, String>,
    pub num_servers_queried: i32,
    pub num_servers_responded: i32,
    pub num_segments_queried: i32,
    pub num_segments_processed: i32,
    pub num_segments_matched: i32,
    pub num_consuming_segments_queried: i32,
    pub num_docs_scanned: i64,
    pub num_entries_scanned_in_filter: i64,
    pub num_entries_scanned_post_filter: i64,
    pub num_groups_limit_reached: bool,
    pub total_docs: i64,
    pub time_used_ms: i32,
    pub min_consuming_freshness_time_ms: i64,
}

PQL

PqlResponse is defined as:

/// PqlResponse is the data structure for broker response to a PQL query.
#[derive(Clone, Debug, PartialEq)]
pub struct PqlResponse {
    pub aggregation_results: Vec<AggregationResult>,
    pub selection_results: Option<SelectionResults>,
    pub stats: Option<ResponseStats>,
}

SQL

SqlResponse is defined as:

/// SqlResponse is the data structure for a broker response to an SQL query.
#[derive(Clone, Debug, PartialEq)]
pub struct SqlResponse<T: FromRow> {
    pub table: Option<Table<T>>,
    pub stats: Option<ResponseStats>,
}

Table is defined as:

/// Table is the holder for SQL queries.
#[derive(Clone, Debug, PartialEq)]
pub struct Table<T: FromRow> {
    schema: Schema,
    rows: Vec<T>,
}

Schema is defined as:

/// Schema is response schema with a bimap to allow easy name <-> index retrieval
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct Schema {
    column_data_types: Vec<DataType>,
    column_name_to_index: bimap::BiMap::<String, usize>,
}

There are multiple functions defined for Schema, like:

fn get_column_count(&self) -> usize;
fn get_column_name(&self, column_index: usize) -> Result<&str>;
fn get_column_index(&self, column_name: &str) -> Result<usize>;
fn get_column_data_type(&self, column_index: usize) -> Result<DataType>;
fn get_column_data_type_by_name(&self, column_name: &str) -> Result<DataType>;

DataType is defined as:

/// Pinot native types
#[derive(Clone, Debug, Eq, PartialEq)]
pub enum DataType {
    Int,
    Long,
    Float,
    Double,
    Boolean,
    Timestamp,
    String,
    Json,
    Bytes,
    IntArray,
    LongArray,
    FloatArray,
    DoubleArray,
    BooleanArray,
    TimestampArray,
    StringArray,
    BytesArray,
}

FromRow is defined as:

/// FromRow represents any structure which can deserialize
/// the Table.rows json field provided a `Schema`
pub trait FromRow: Sized {
    fn from_row(
        data_schema: &Schema,
        row: Vec<Value>,
    ) -> std::result::Result<Self, serde_json::Error>;
}

In addition to being implemented by DataRow, FromRow is also implemented by all implementors of serde::de::Deserialize, which is achieved by first deserializing the response to json and then before each row is deserialized into final form, a json map of column name to value is substituted. Additionally, there are a number of serde deserializer functions provided to deserialize complex pinot types:

/// Converts Pinot timestamps into `Vec<DateTime<Utc>>` using `deserialize_timestamps_from_json()`.
fn deserialize_timestamps<'de, D>(deserializer: D) -> std::result::Result<Vec<DateTime<Utc>>, D::Error>...

/// Converts Pinot timestamps into `DateTime<Utc>` using `deserialize_timestamp_from_json()`.
pub fn deserialize_timestamp<'de, D>(deserializer: D) -> std::result::Result<DateTime<Utc>, D::Error>...

/// Converts Pinot hex strings into `Vec<Vec<u8>>` using `deserialize_bytes_array_from_json()`.
pub fn deserialize_bytes_array<'de, D>(deserializer: D) -> std::result::Result<Vec<Vec<u8>>, D::Error>...

/// Converts Pinot hex string into `Vec<u8>` using `deserialize_bytes_from_json()`.
pub fn deserialize_bytes<'de, D>(deserializer: D) -> std::result::Result<Vec<u8>, D::Error>...

/// Deserializes json potentially packaged into a string by calling `deserialize_json_from_json()`.
pub fn deserialize_json<'de, D>(deserializer: D) -> std::result::Result<Value, D::Error>

For example usage, please refer to this example

DataRow is defined as:

/// A row of `Data`
#[derive(Clone, Debug, PartialEq)]
pub struct DataRow {
    row: Vec<Data>,
}

Data is defined as:

/// Typed Pinot data
#[derive(Clone, Debug, PartialEq)]
pub enum Data {
    Int(i32),
    Long(i64),
    Float(f32),
    Double(f64),
    Boolean(bool),
    Timestamp(DateTime<Utc>),
    String(String),
    Json(Value),
    Bytes(Vec<u8>),
    IntArray(Vec<i32>),
    LongArray(Vec<i64>),
    FloatArray(Vec<f32>),
    DoubleArray(Vec<f64>),
    BooleanArray(Vec<bool>),
    TimestampArray(Vec<DateTime<Utc>>),
    StringArray(Vec<String>),
    BytesArray(Vec<Vec<u8>>),
    Null(DataType),
}

There are multiple functions defined for Data, like:

fn data_type(&self) -> DataType;
fn get_int(&self) -> Result<i32>;
fn get_long(&self) -> Result<i64>;
fn get_float(&self) -> Result<f32>;
fn get_double(&self) -> Result<f64>;
fn get_boolean(&self) -> Result<bool>;
fn get_timestamp(&self) -> Result<DateTime<Utc>>;
fn get_string(&self) -> Result<&str>;
fn get_json(&self) -> Result<&Value>;
fn get_bytes(&self) -> Result<&Vec<u8>>;
fn is_null(&self) -> bool;

In addition to row count, DataRow also contains convenience counterparts to those above given a column index.