simdb is a small Go library for saving structs in ordinary JSON files and performing basic CRUD operations and conditional reads. It is aimed at low-volume local apps—such as Raspberry Pi projects—not server-database workloads. To use it, create a driver, give each persisted struct an ID() method, then call methods such as Insert, Open, Where, Get, Update and Delete.
What simdb does
simdb stores Go structs in JSON files and exposes a small API for inserting, reading, updating and deleting records. It is file-backed rather than a database server: the data remains human-readable JSON, and the library is intended for less data-intensive applications. The original author describes using JSON storage for Raspberry Pi projects that keep execution rules and sensor details. Project documentation
That simplicity comes with trade-offs. The author has said the query syntax needs a better approach, and the available project information does not establish benchmark performance, transaction support, durability guarantees, replication, or formal concurrency guarantees. Treat simdb as a lightweight local-storage option, not as a substitute for a database whose workload depends on those properties.
How to use simdb
The package’s documented pattern is to create a driver for a directory, define an entity with an identifier method, insert it, then open the entity’s store to query or change records. The examples below describe that API pattern; check the package documentation for the exact import path and signatures of the version you choose.
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1. Create a driver and an entity type
Create a driver with db.New("dbs"), where dbs is the storage directory in the example. A persistable type must implement the Entity interface by providing an ID() method that returns the identifier field and value used to locate a record. See the project examples for the precise method shape.
Conceptually, the entity is a regular Go struct plus the required identifier behavior. The ID is important beyond insertion: the documented update and delete examples use it to identify which record to change or remove.
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2. Insert a record
Pass an entity to Insert(entity) to create or append a record in the JSON-backed store. The package documentation describes the storage as JSON files selected according to the entity type and database setup. Package documentation
3. Read all records or filter them
Call Open(Entity{}) to select the store for the entity type. Add one or more Where(key, operator, value) conditions and then call Get() to retrieve matching records. Call First() when you want the first match instead. Convert the result into a struct or slice with AsEntity(&value) or AsEntity(&slice).
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The documented query mechanism is intentionally basic; the author explicitly noted that simdb’s query syntax was not very good and needed improvement. Avoid assuming it offers the expressive query language, indexing, or optimization features of a full database.
4. Update or delete by entity identity
Pass an entity to Update(entity) to change a stored record, or to Delete(entity) to remove it. The examples rely on the entity ID for locating the target, so implement a stable identifier before using these operations.
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The driver surface also documents Upsert, along with Raw, RawArray, Path, Close, Errors and Clone. Exported errors include ErrRecordNotFound and ErrUpdateFailed. Consult the documentation for the version in use to understand the return values and error-handling details of each method.
Is simdb a good fit?
Consider it for small local data
- Your application has modest amounts of data and runs locally.
- You want to inspect or edit the stored JSON directly.
- Your records map naturally to Go structs and simple identifier-based changes.
- A small utility or Raspberry Pi application needs straightforward persistence rather than a database service.
Choose a different store when guarantees matter
- Your workload needs well-developed query syntax or complex filtering.
- Multiple writers, concurrent access, transactions, durability guarantees or replication are requirements.
- You need measured performance or evidence that the store handles a particular volume.
The available simdb documentation does not establish those latter capabilities. Evaluate alternatives against your own needs for JSON readability, schema flexibility, query expressiveness, write concurrency, durability, dependency footprint, operational effort and expected data volume; do not infer guarantees from the fact that the data is stored in a file.
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Project version and maintenance context
The original project is associated with the sonyarouje/simdb repository. A separate adampresley/simdb fork describes Go Modules support and other tweaks; pkg.go.dev lists its v1.0.5 publication date as July 1, 2020. That historical release listing does not establish whether the fork or original project is currently maintained. Check the repository and package information for the version you intend to use before adopting it.
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