[−][src]Crate emseries
An Embedded Time Series Database
This library provides a low-intensity time series database meant to be embedded inside of an application.
From the signature of the series
pub struct Series<T: Clone + Recordable + DeserializeOwned + Serialize> {
you can know that you must parameterize the series over the data type that you want to store, which must also have several traits implemented.
#[derive(Clone, Debug, PartialEq, Deserialize, Serialize)]
struct BikeTrip {
datetime: DateTime<Utc>,
distance: Distance,
duration: Duration,
comments: String,
}
impl Recordable for BikeTrip {
fn timestamp(&self) -> DateTime<Utc> {
self.datetime
}
fn tags(&self) -> Vec<String> {
Vec::new()
}
}
Recordable requires implementations for timestamp
and tags
, both of which can be used for
searching for records, and both of which may be used for indexing in the future.
The series can only store a single data type, but you can always store multiple data types by wrapping them into a single enum.
Open the series:
let mut ts: Series<BikeTrip> = Series::open("var/bike_trips.json")
.expect("expect the time series to open correctly");
The series file will be created if it does not already exist. If it does already exist, the existing data will be read into memory and made available.
Note: all of the data is read into memory at once. For human-scale things, this probably takes up very little memory, but this software is not optimized for IoT scale deployments. Additionally, this library assumes only one process is writing to the file. Behavior from more than one process writing to the file is currently undefined.
Structs
And | Specify two criteria that must both be matched. |
DateTimeTz | This is a wrapper around date time objects, using timezones from the chroon-tz database and
providing string representation and parsing of the form " |
EndTime | Specify the ending time for a search. This consists of a UTC timestamp and a specifier as to whether the exact time is included in the search criteria. |
Or | Specify two criteria, either of which may be matched. |
Series | An open time series database. |
StartTime | Specify the starting time for a search. This consists of a UTC timestamp and a specifier as to whether the exact time is included in the search criteria. |
Tags | Specify a list of tags that must exist on the record. |
UniqueId | Uniquely identifies a record. |
Enums
Error | Errors for the database |
Traits
Criteria | This trait is used for constructing queries for searching the database. |
Recordable | Any element to be put into the database needs to be Recordable. This is the common API that will aid in searching and later in indexing records. |
Functions
exact_time | Specify a criteria that searches for records matching an exact time. |
time_range | Specify a criteria that searches for all records within a time range. |