Serilog.Sinks.SQLite 7.0.0-dev

Serilog.Sinks.SQLite

A lightweight, high-performance Serilog sink that writes to a SQLite database.

Getting started

Install Serilog.Sinks.SQLite from NuGet:

Install-Package Serilog.Sinks.SQLite

Configure the logger with WriteTo.SQLite():

var logger = new LoggerConfiguration()
    .WriteTo.SQLite(@"Logs\log.db")
    .CreateLogger();

logger.Information("This informational message will be written to SQLite database");

Configuration

.WriteTo.SQLite(
    sqliteDbPath:       "Logs/log.db",
    tableName:          "Logs",
    storeTimestampInUtc: false,
    retentionPeriod:    TimeSpan.FromDays(7),     // default null (no expiry)
    batchSize:          100,                       // 1..1000
    maxDatabaseSize:    10,                        // MB, capped at ~20 GB
    rollOver:           true,                      // create sibling DB when full
    journalMode:        SqliteJournalMode.Wal)     // see notes below

Journal mode

Default is WAL (write-ahead log) — crash-safe with concurrent readers. WAL is persisted in the database file, so the first run against an older database converts it. To opt out of WAL, set journalMode: SqliteJournalMode.Memory (fast, but corrupts on crash) or Delete (legacy default).

Buffer overflow

The sink holds events in a 100 000-entry in-memory queue while batches are being flushed. When the queue fills (slow disk, stuck writer), additional events are dropped and the running drop count is reported through Serilog's SelfLog at 1, 1000, 2000, … events.

Roll-over

When the database reaches maxDatabaseSize, the sink uses VACUUM INTO to produce an atomic sibling backup named <name>-yyyyMMdd_HHmmss.ff-<guid>.db, then truncates and reuses the original file. Sidecar WAL contents are captured. Disable with rollOver: false to instead drop overflowing batches.

XML <appSettings> configuration

To use the SQLite sink with the Serilog.Settings.AppSettings package:

Install-Package Serilog.Settings.AppSettings

In your code:

var logger = new LoggerConfiguration()
    .ReadFrom.AppSettings()
    .CreateLogger();

In App.config / Web.config:

<appSettings>
    <add key="serilog:using:SQLite" value="Serilog.Sinks.SQLite"/>
    <add key="serilog:write-to:SQLite.sqliteDbPath" value="Logs\log.db"/>
    <add key="serilog:write-to:SQLite.tableName" value="Logs"/>
    <add key="serilog:write-to:SQLite.storeTimestampInUtc" value="true"/>
</appSettings>

Performance

The sink buffers events internally and flushes to SQLite in batches on a dedicated thread. Properties are serialised once outside the database transaction, so commit latency is bounded by I/O rather than JSON work. When a retentionPeriod is configured, the sink also creates IX_<table>_Timestamp so the periodic delete is O(log n) instead of a full scan.

Breaking changes in 7.0

• Targets netstandard2.0 + net8.0; net7.0 dropped.
• Serilog 4.x required.
• Storage layer switched to Microsoft.Data.Sqlite (was System.Data.SQLite). True cross-platform — no native interop quirks on Linux/macOS.
• Properties JSON now produced by System.Text.Json (was Newtonsoft.Json). Output uses the relaxed encoder so payloads stay human-readable, but <, >, &, ' will not be escaped to \u00xx anymore.
• Exception and Properties columns store NULL when the event has none (previously empty strings).