CamusDB.EntityFrameworkCore 0.6.5

CamusDB Connector for .NET

.NET idiomatic client libraries for CamusDB

This repository contains two packages:

Package	Description
CamusDB.Client	ADO.NET provider — recommended for direct database access from .NET
CamusDB.EntityFrameworkCore	Entity Framework Core provider built on top of CamusDB.Client

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CamusDB.Client (ADO.NET)

Installation

dotnet add package CamusDB.Client

Or via the Package Manager Console:

Install-Package CamusDB.Client

Configuration

Create a CamusConnectionStringBuilder with a connection string:

using CamusDB.Client;

CamusConnectionStringBuilder builder = new("Endpoint=http://localhost:8082;Database=test");
await using CamusConnection connection = new(builder);

await connection.OpenAsync();

Supported connection string keys:

Key	Required	Description
Endpoint	Yes	Base URL for the CamusDB HTTP endpoint.
Database	Yes	Database name sent with requests.
Timeout	No	HTTP request timeout in seconds (default: 10).

Endpoint also supports a comma-separated pool. The client selects endpoints with round-robin routing:

CamusConnectionStringBuilder builder = new(
    "Endpoint=http://localhost:8082,http://localhost:8084,http://localhost:8086;Database=test");

When a request fails because an endpoint is unreachable, that endpoint is marked unavailable and skipped by later requests made through the same CamusConnectionStringBuilder.

Usage

Database Management

CamusDB requires databases to be explicitly created before use. Call CreateDatabaseAsync once during application startup or provisioning:

// Create the database (no-op if it already exists)
await connection.CreateDatabaseAsync(ifNotExists: true);

To drop a database:

await connection.DropDatabaseAsync();

Both methods operate on the database named in the connection string. An explicit name can also be passed:

await connection.CreateDatabaseAsync("otherdb", ifNotExists: true);
await connection.DropDatabaseAsync("otherdb");

Ping

await using CamusCommand ping = connection.CreatePingCommand();

int result = await ping.ExecuteNonQueryAsync();

Execute DDL

await using CamusCommand command = connection.CreateCamusCommand("""
    CREATE TABLE robots (
        id OID PRIMARY KEY NOT NULL,
        name STRING NOT NULL,
        type STRING,
        year INT64,
        price FLOAT64,
        enabled BOOL
    )
    """);

bool created = await command.ExecuteDDLAsync();

CamusDB supports CHECK and named NOT NULL constraints, addable and droppable via ALTER TABLE. A CHECK is a deterministic single-row predicate evaluated on every insert and update; a row is rejected only when the predicate is FALSE (a NULL operand yields UNKNOWN, which passes). A violation throws a CamusException with code CADB0303; a named NOT NULL violation throws CADB0301. Both kinds are dropped by name with DROP CONSTRAINT:

await connection.CreateCamusCommand("""
    CREATE TABLE products (
        id       OID PRIMARY KEY NOT NULL,
        name     STRING CONSTRAINT products_name_required NOT NULL,
        price    INT64 CHECK (price > 0),
        discount INT64,
        CONSTRAINT valid_discount CHECK (price >= discount)
    )
    """).ExecuteDDLAsync();

// Add / drop after the fact (ADD CHECK scans existing rows and rejects if any violate it)
await connection.CreateCamusCommand(
    "ALTER TABLE products ADD CONSTRAINT positive_price CHECK (price > 0)").ExecuteDDLAsync();
await connection.CreateCamusCommand(
    "ALTER TABLE products DROP CONSTRAINT positive_price").ExecuteDDLAsync();

Data Types

CamusDB columns are declared with these SQL types; each maps to a ColumnType on the wire and a CLR type the reader/parameters understand:

SQL DDL type	ColumnType	CLR type(s)	Notes
OID (alias OBJECT_ID)	Id	string, Guid, CamusObjectIdValue	Native identifier; shares string key encoding.
UUID (alias GUID)	Uuid	Guid	Native 128-bit UUID; indexable, ordered by big-endian byte order. gen_uuid_v4() / gen_uuid_v7() generate values server-side.
INT64 (aliases INT, INTEGER)	Integer64	long, int, short, byte	64-bit signed.
FLOAT64	Float64	double	IEEE-754 double.
FLOAT32 (alias REAL)	Float32	float	Stored at single precision.
BOOL (alias BOOLEAN)	Bool	bool
STRING / STRING(N)	String	string	N bounds the length (UTF-16 code units); over-length is rejected.
DATE	Date	DateOnly, DateTime	Calendar date; stored as UTC ticks at midnight.
DATETIME (alias TIMESTAMP)	DateTime	DateTime, DateTimeOffset	Instant; normalized to UTC and read back as DateTimeKind.Utc.
BYTES (alias BLOB)	Bytes	byte[]	base64 over JSON, 0x-hex in SQL literals. Default max 10 MB.
ARRAY(T)	Array	any IEnumerable of T	Homogeneous scalar list; not indexable, no inline SQL literal.

await using CamusCommand command = connection.CreateCamusCommand("""
    CREATE TABLE events (
        id        OID PRIMARY KEY NOT NULL,
        ref       UUID DEFAULT gen_uuid_v7(),
        name      STRING(64),
        payload   BYTES,
        score     FLOAT32,
        happened  DATETIME,
        day       DATE,
        tags      ARRAY(INT64)
    )
    """);

await command.ExecuteDDLAsync();

Dates/datetimes are normalized to UTC before being sent. Arrays carry a scalar element type, inferred from the values or set explicitly (required for an empty array):

await using CamusCommand insert = connection.CreateInsertCommand("events");

insert.Parameters.Add("id", ColumnType.Id, CamusObjectIdGenerator.Generate());
insert.Parameters.Add("ref", ColumnType.Uuid, Guid.NewGuid());
insert.Parameters.Add("name", ColumnType.String, "launch");
insert.Parameters.Add("payload", ColumnType.Bytes, new byte[] { 0xDE, 0xAD });
insert.Parameters.Add("score", ColumnType.Float32, 9.5f);
insert.Parameters.Add("happened", ColumnType.DateTime, DateTime.UtcNow);
insert.Parameters.Add("day", ColumnType.Date, new DateOnly(2026, 5, 1));
insert.Parameters.Add("tags", ColumnType.Integer64, new long[] { 1, 2, 3 }, isArray: true);

await insert.ExecuteNonQueryAsync();

Reading them back uses the typed CamusDataReader accessors:

Guid      reference = reader.GetGuid(reader.GetOrdinal("ref"));
byte[]    payload  = reader.GetFieldValue<byte[]>(reader.GetOrdinal("payload"));
float     score    = reader.GetFloat(reader.GetOrdinal("score"));
DateTime  happened = reader.GetDateTime(reader.GetOrdinal("happened"));
DateOnly  day      = reader.GetFieldValue<DateOnly>(reader.GetOrdinal("day"));
object?[] tags     = (object?[])reader.GetValue(reader.GetOrdinal("tags"));

Insert Rows

using CamusDB.Core.Util.ObjectIds;

await using CamusCommand insert = connection.CreateInsertCommand("robots");

insert.Parameters.Add("id", ColumnType.Id, CamusObjectIdGenerator.Generate());
insert.Parameters.Add("name", ColumnType.String, "T-800");
insert.Parameters.Add("type", ColumnType.String, "cyborg");
insert.Parameters.Add("year", ColumnType.Integer64, 1984);
insert.Parameters.Add("price", ColumnType.Float64, 10.0);
insert.Parameters.Add("enabled", ColumnType.Bool, true);

int insertedRows = await insert.ExecuteNonQueryAsync();

You can also execute parameterized SQL:

const string sql = """
    INSERT INTO robots (id, name, year, type, price, enabled)
    VALUES (GEN_ID(), @name, @year, @type, @price, @enabled)
    """;

await using CamusCommand insert = connection.CreateCamusCommand(sql);

insert.Parameters.Add("@name", ColumnType.String, "R2-D2");
insert.Parameters.Add("@year", ColumnType.Integer64, 1977);
insert.Parameters.Add("@type", ColumnType.String, "mechanical");
insert.Parameters.Add("@price", ColumnType.Float64, 25.5);
insert.Parameters.Add("@enabled", ColumnType.Bool, true);

int insertedRows = await insert.ExecuteNonQueryAsync();

See Data Types above for inserting bytes, float32, date, datetime and array(T) values.

Select Rows

await using CamusCommand select = connection.CreateSelectCommand(
    "SELECT * FROM robots WHERE year = @year");

select.Parameters.Add("@year", ColumnType.Integer64, 1977);

CamusDataReader reader = await select.ExecuteReaderAsync();

while (await reader.ReadAsync())
{
    string id   = reader.GetString(0);
    string name = reader.GetString(1);
    string type = reader.GetString(2);
    long   year = reader.GetInt64(3);
}

Query Result Cache

CamusDB has an opt-in, per-node, in-memory cache of fully materialized SELECT results. A query joins it with an inline {cache=name} hint placed right after a table reference; an identical later query (same shape, same bound values, same schema) can then be served from memory. The cache only serves single-table, autocommit reads — hints on joins or inside explicit transactions are inert.

Add the hint directly in your SQL, optionally with a per-entry TTL or strict (validate every hit against live storage). CamusCacheHint.Build(...) assembles the fragment for you:

string hint = CamusCacheHint.Build("recent_orders", ttl: TimeSpan.FromSeconds(30));

await using CamusCommand select = connection.CreateSelectCommand(
    $"SELECT id, total FROM orders {hint} WHERE status = @status ORDER BY total DESC LIMIT 20");

select.Parameters.Add("@status", ColumnType.Integer64, 1);

CamusDataReader reader = await select.ExecuteReaderAsync();

// Inspect how the server resolved the cache for this query.
CamusCacheMetadata? cache = reader.CacheMetadata;   // also on select.LastCacheMetadata
if (cache is not null)
    Console.WriteLine($"{cache.Status} ({cache.Name}), age={cache.AgeMs}ms");

CamusCacheMetadata exposes Status (Hit, Miss, Bypass, StaleRevalidated, EvictedBeforePublish), BypassReason, Name, CachedAtHlc, and AgeMs. It is null for any query that carried no hint, so ordinary queries are unaffected.

Evict entries manually — both are scoped to the current database:

await connection.EvictCacheAsync("recent_orders");   // one family
await connection.EvictAllCacheAsync();               // every entry for this database

Transactions

CamusTransaction transaction = await connection.BeginTransactionAsync();

await using CamusCommand insert = connection.CreateInsertCommand("robots");
insert.Transaction = transaction;

insert.Parameters.Add("id", ColumnType.Id, CamusObjectIdGenerator.Generate());
insert.Parameters.Add("name", ColumnType.String, "HAL 9000");
insert.Parameters.Add("type", ColumnType.String, "electronic");
insert.Parameters.Add("year", ColumnType.Integer64, 1968);
insert.Parameters.Add("price", ColumnType.Float64, 42.0);
insert.Parameters.Add("enabled", ColumnType.Bool, true);

await insert.ExecuteNonQueryAsync();
await transaction.CommitAsync();

Use await transaction.RollbackAsync() to roll back instead.

Isolation level, mode, and optimistic locking

A transaction has three independent concurrency knobs, passed as CamusTransactionOptions:

Knob	Values	Default
IsolationLevel	Serializable, ReadCommitted	server default (Serializable)
Mode	ReadWrite, ReadOnly	ReadWrite
Locking	Pessimistic, Optimistic	server default (Pessimistic)

Optimistic locking skips the explicit write lock: writes are staged and the rows read are version-recorded, and write–write / read–write conflicts are validated at commit, where the loser throws a CamusException you replay (see Serializable Isolation & Retries). It trades write-time blocking for commit-time validation — good for low-contention, read-mostly workloads.

Optimistic is orthogonal to the isolation level, and it does not mean "lock-free" at both levels:

• Read Committed + Optimistic is fully lock-free, but phantom-vulnerable — its validation covers only the specific rows it read, not predicates.
• Serializable + Optimistic is a hybrid: it still takes the shared range/point (predicate) locks, so it stays phantom-free, while validating its write/read set at commit.

Phantom protection is gated on the isolation level (Serializable), not on the locking mode — so use Serializable (pessimistic or optimistic) when you need it; either locking mode under ReadCommitted is phantom-vulnerable.

// Optimistic transaction
CamusTransaction tx = await connection.BeginTransactionAsync(CamusTransactionOptions.Optimistic);

// Or select knobs explicitly
CamusTransaction rc = await connection.BeginTransactionAsync(new CamusTransactionOptions
{
    IsolationLevel = CamusIsolationLevel.ReadCommitted,
    Locking = CamusLocking.Optimistic,
});

// A lock-free consistent snapshot (Serializable read-only), resumable across requests
CamusTransaction snap = await connection.BeginTransactionAsync(CamusTransactionOptions.Snapshot);

Any knob left unset defers to the connection-string defaults, then the server default. Set connection-wide defaults (which also apply to autocommit statements) via the IsolationLevel=, TransactionMode=, and Locking= connection-string keys (values are case-insensitive):

Endpoint=http://localhost:5095;Database=test;Locking=Optimistic;IsolationLevel=ReadCommitted;TransactionMode=ReadWrite

Precedence: per-transaction options › connection-string defaults › server default. The equivalent SQL passthrough — SET TRANSACTION LOCKING { PESSIMISTIC | OPTIMISTIC } and SET TRANSACTION ISOLATION LEVEL …, issued as the first statement of an explicit transaction — also works.

Serializable Isolation & Retries

Serializable is the default isolation level in CamusDB. When two serializable transactions conflict, one is aborted immediately and must be replayed from BEGIN — retrying a single statement is not safe.

Three error codes indicate a transient conflict that a full retry can resolve:

Code	Name	When raised
CADB0502	TransactionConflict	Lock conflict; server aborted at lock-acquire time
CADB0504	TransactionMustRetry	Routing retry budget exhausted; no data written
CADB0505	TransactionLifetimeExceeded	Transaction held open past the server lifetime limit

A fourth code, CADB0509 (TransactionFinalizeUnresolved), is a different kind of retry and is not replay-retryable: it means a COMMIT/ROLLBACK outcome is not yet resolved, and the fix is to re-issue the same finalize on the same transaction — never to replay the operation (the commit may already have durably applied). CamusTransaction.CommitAsync/RollbackAsync handle this transparently (bounded re-issue with back-off), and SerializableRetryHelper.IsRetryable returns false for it so it never enters a replay-from-BEGIN loop.

Use SerializableRetryHelper.IsRetryable(ex) to test any exception, and SerializableRetryHelper.ExecuteAutocommitAsync for bounded automatic retry of single-statement (autocommit) operations:

await SerializableRetryHelper.ExecuteAutocommitAsync(async ct =>
{
    CamusTransaction tx = await connection.BeginTransactionAsync(ct);
    try
    {
        await using CamusCommand cmd = connection.CreateCamusCommand(
            "UPDATE robots SET price = @price WHERE name = @name");
        cmd.Transaction = tx;
        cmd.Parameters.Add("@price", ColumnType.Float64, 99.0);
        cmd.Parameters.Add("@name",  ColumnType.String,  "T-800");
        await cmd.ExecuteNonQueryAsync(ct);
        await tx.CommitAsync(ct);
    }
    catch
    {
        await tx.RollbackAsync(ct);
        throw;
    }
}, maxAttempts: 5, cancellationToken);

Back-off schedule: min(20 ms × 2^attempt, 400 ms) ± 25 % jitter. Any non-retryable exception propagates immediately.

For explicit multi-statement transactions, own the retry loop yourself so you can replay every read and write from scratch:

const int MaxAttempts = 5;
int attempt = 0;

while (true)
{
    CamusTransaction tx = await connection.BeginTransactionAsync();
    try
    {
        // re-execute ALL reads and writes on every attempt
        long balance = await ReadBalance(tx, accountId);
        if (balance < amount)
            throw new InvalidOperationException("Insufficient funds");
        await Debit(tx, accountId, balance - amount);
        await tx.CommitAsync();
        break;
    }
    catch (CamusException ex) when (SerializableRetryHelper.IsRetryable(ex))
    {
        await tx.RollbackAsync();
        if (++attempt >= MaxAttempts)
            throw;
        await Task.Delay(20 * (1 << attempt));
    }
    catch
    {
        await tx.RollbackAsync();
        throw;
    }
}

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CamusDB.EntityFrameworkCore (EF Core)

Installation

dotnet add package CamusDB.EntityFrameworkCore

Or via the Package Manager Console:

Install-Package CamusDB.EntityFrameworkCore

Configuration

Register the provider via UseCamusDB in your DbContext options:

using CamusDB.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore;

var options = new DbContextOptionsBuilder<AppDbContext>()
    .UseCamusDB("Endpoint=http://localhost:8082;Database=mydb;Timeout=30")
    .Options;

Or configure it inside OnConfiguring:

public class AppDbContext : DbContext
{
    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        => optionsBuilder.UseCamusDB("Endpoint=http://localhost:8082;Database=mydb");
}

The same connection string keys are supported as in CamusDB.Client — see the connection string reference above.

Retry on failure

Call EnableRetryOnFailure on the CamusDBDbContextOptionsBuilder to let EF Core automatically retry SaveChangesAsync (and query execution) when a transient serialization conflict is detected. A retry fires on the three retryable CamusDB error codes (CADB0502, CADB0504, CADB0505) as well as the transient contention markers the server reports in the message (MustRetry, AlreadyLocked, commit returned Aborted) — all other exceptions propagate immediately.

var options = new DbContextOptionsBuilder<AppDbContext>()
    .UseCamusDB("Endpoint=http://localhost:8082;Database=mydb", o =>
    {
        o.EnableRetryOnFailure();
    })
    .Options;

Default parameters:

Parameter	Default	Description
maxRetryCount	15	Maximum number of retry attempts
maxRetryDelay	1 s	Upper bound on the delay between retries
retryDeadline	5 s	Wall-clock deadline from first failure; no further retries after this
medianFirstRetryDelay	30 ms	Median delay before the first retry

Override any parameter explicitly:

o.EnableRetryOnFailure(
    maxRetryCount: 5,
    maxRetryDelay: TimeSpan.FromMilliseconds(500),
    retryDeadline: TimeSpan.FromSeconds(3),
    medianFirstRetryDelay: TimeSpan.FromMilliseconds(20));

Optimistic locking & isolation defaults

Make every transaction and autocommit statement on a context use optimistic locking (no locks; conflicts detected at commit). Pair it with EnableRetryOnFailure() so EF replays a losing unit of work:

var options = new DbContextOptionsBuilder<AppDbContext>()
    .UseCamusDB("Endpoint=http://localhost:8082;Database=mydb", o =>
    {
        o.UseOptimisticLocking();   // or o.UsePessimisticLocking()
        o.EnableRetryOnFailure();
    })
    .Options;

For finer control, UseTransactionDefaults(new CamusTransactionOptions { … }) sets the default isolation level, mode, and locking together. Any knob left unset defers to the connection-string / server default, and a per-transaction selection (e.g. Database.BeginTransaction(IsolationLevel.ReadCommitted)) overrides these. IsolationLevel.ReadCommitted, Serializable, and Snapshot all map through to CamusDB.

EF Core's execution strategy retries the entire unit of work — never only the failing statement. If you manage transactions manually with BeginTransactionAsync / CommitTransactionAsync, use SerializableRetryHelper in CamusDB.Client instead.

Sharing an existing connection

Pass an open CamusConnection when you want to share a connection or attach to an externally managed transaction:

CamusConnection connection = await GetOpenConnectionAsync();

var options = new DbContextOptionsBuilder<AppDbContext>()
    .UseCamusDB(connection)
    .Options;

await using var ctx = new AppDbContext(options);
await ctx.Database.BeginTransactionAsync();
// ... SaveChangesAsync, then CommitTransactionAsync

The DbContext does not take ownership of the supplied connection and will not close or dispose it.

Defining a Model

Use standard EF Core data annotations or the fluent API. Map ID columns to the "id" store type and call ValueGeneratedOnAdd() so the provider generates a client-side ObjectId automatically:

public class Robot
{
    public string Id   { get; set; } = "";
    public string Name { get; set; } = "";
    public string Type { get; set; } = "";
    public int    Year { get; set; }
    public double Price   { get; set; }
    public bool   Enabled { get; set; }
}

public class AppDbContext : DbContext
{
    public DbSet<Robot> Robots => Set<Robot>();

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Robot>(b =>
        {
            b.ToTable("robots");
            b.HasKey(e => e.Id);
            b.Property(e => e.Id)
             .HasColumnType("id")
             .ValueGeneratedOnAdd();   // client-side ObjectId generation
            b.Property(e => e.Name).HasColumnType("string");
            b.Property(e => e.Type).HasColumnType("string");
            b.Property(e => e.Year).HasColumnType("int64");
            b.Property(e => e.Price).HasColumnType("float64");
            b.Property(e => e.Enabled).HasColumnType("bool");
        });
    }
}

Add a CHECK constraint with ToTable(t => t.HasCheckConstraint(...)). It is enforced server-side on every insert and update, and rejected rows surface as a DbUpdateException whose inner CamusException carries code CADB0303:

b.ToTable("robots", t => t.HasCheckConstraint("ck_robots_price", "price >= 0"));

CamusDB Type Mapping

CLR type	CamusDB store type	DDL type
string (ID / PK)	id or oid	OID
Guid (ID / PK)	id or oid	OID
Guid + HasColumnType("uuid")	uuid (alias guid)	UUID
string	string	STRING
string + HasMaxLength(n)	string	STRING(n)
bool	bool	BOOL
short, int, long	int64	INT64
float	float32	FLOAT32
double	float64	FLOAT64
byte[]	bytes (alias blob)	BYTES
DateOnly	date	DATE
DateTime, DateTimeOffset	datetime (alias timestamp)	DATETIME
long[], string[], double[], bool[]	array(int64/string/float64/bool)	ARRAY(T)

Use HasColumnType("id") (or the alias "oid") for primary key columns backed by CamusDB ObjectIds. The provider sends the value as an OID on the wire regardless of whether the CLR property is string or Guid.

A plain Guid property defaults to the id/OID store type for backward compatibility. To store it as CamusDB's native UUID column instead — indexable and ordered by big-endian byte order — declare it explicitly with HasColumnType("uuid"):

b.Property(e => e.ExternalRef).HasColumnType("uuid");

Dates and datetimes are stored as UTC ticks; the provider normalizes DateTime values to UTC before sending and reconstructs them as DateTimeKind.Utc. byte[] is exchanged as base64 over the JSON wire (SQL literals use 0x-hex). A string property maps to float32/bytes/date/datetime etc. either by its CLR type or by an explicit HasColumnType(...).

long[], string[], double[], and bool[] properties map to CamusDB native ARRAY(T) columns (not EF's JSON "primitive collection" — the provider registers a direct mapping that stores a real array). No HasColumnType is required; declare the property as usual:

b.Property(e => e.Tags);   // long[]  → ARRAY(INT64)

Arrays are not indexable and have no inline SQL literal, so an array value can only travel as a bound parameter — it cannot appear in a Where(...) predicate, as a default value, or in migration seed data.

Database and Table Lifecycle

EnsureCreatedAsync() creates the database and all tables defined in the model. Both operations are idempotent — it is safe to call on a database or tables that already exist:

await using var ctx = new AppDbContext();
await ctx.Database.EnsureCreatedAsync();

EnsureDeletedAsync() drops the database entirely:

await ctx.Database.EnsureDeletedAsync();

Insert

await using var ctx = new AppDbContext();

ctx.Robots.Add(new Robot
{
    Name    = "T-800",
    Type    = "cyborg",
    Year    = 1984,
    Price   = 10.0,
    Enabled = true
});

await ctx.SaveChangesAsync(); // Id is generated automatically

Query

await using var ctx = new AppDbContext();

// Key lookup
Robot? robot = await ctx.Robots.FindAsync(id);

// LINQ predicate
List<Robot> active = await ctx.Robots
    .Where(r => r.Enabled && r.Year > 1980)
    .ToListAsync();

The provider translates a broad set of LINQ shapes to server-side SQL: Where, OrderBy/ThenBy, Skip/Take, Distinct, scalar aggregates (Count, Sum, Average, Min, Max, Any), GroupBy + aggregate, inner joins, and correlated subqueries (Where(x => x.Items.Any(...))).

The following string members translate to CamusDB's native scalar/predicate functions and run on the server (rather than forcing client-side evaluation):

LINQ	CamusDB function
s.StartsWith(x) / s.EndsWith(x) / s.Contains(x)	starts_with / ends_with / contains
s.StartsWith(x, StringComparison.OrdinalIgnoreCase) (and the …IgnoreCase variants)	wrapped in lower(...)
s.ToUpper() / s.ToLower()	upper / lower
s.Trim() / s.TrimStart() / s.TrimEnd()	trim / ltrim / rtrim
s.Replace(a, b)	replace
s.Length	length

The starts_with / ends_with / contains predicates take the search term as a plain argument, so they work with a column or parameter (not just a literal) and need no LIKE wildcard escaping.

Regular expressions

System.Text.RegularExpressions.Regex static calls and the EF.Functions.Regexp* helpers map onto CamusDB's native regex operators and regexp_* scalar functions (PostgreSQL semantics):

LINQ	CamusDB
Regex.IsMatch(s, pattern)	regexp_like(s, pattern) (the ~ operator)
Regex.IsMatch(s, pattern, RegexOptions.IgnoreCase)	regexp_like(s, pattern, 'i') (the ~* operator)
Regex.Replace(s, pattern, repl)	regexp_replace(s, pattern, repl, 'g') (replaces every match, like .NET)
EF.Functions.RegexpLike(s, pattern[, flags])	regexp_like
EF.Functions.RegexpReplace(s, pattern, repl[, flags])	regexp_replace (first match; pass "g" to replace all)
EF.Functions.RegexpCount(s, pattern[, flags])	regexp_count
EF.Functions.RegexpSubstr(s, pattern[, flags])	regexp_substr
EF.Functions.RegexpInstr(s, pattern[, flags])	regexp_instr

using System.Text.RegularExpressions;

var valid = await ctx.People
    .Where(p => Regex.IsMatch(p.Name, "^[A-Z]"))                                   // name ~ '^[A-Z]'
    .Where(p => EF.Functions.RegexpLike(p.Email, "^[^@]+@[^@]+\\.[a-z]+$", "i"))   // email ~* '…'
    .ToListAsync();

The flags string uses PostgreSQL option characters: i case-insensitive, c case-sensitive, m/n multiline, s single-line (dot matches newline), x extended, and g replace-all (for RegexpReplace). A RegexOptions argument to a Regex call is honored only when it is a compile-time constant made of flags CamusDB can express (IgnoreCase, Multiline, Singleline, IgnorePatternWhitespace); anything else leaves the call untranslated. Because these are equivalent to CHECK-constraint predicates, the same patterns work in HasCheckConstraint (e.g. t.HasCheckConstraint("ck_email", "email ~* '^[^@]+@[^@]+$'")). The set-returning functions regexp_matches / regexp_split_to_table are not supported by the server.

Not translatable (server limitations): Include/collection navigations and left/optional joins — CamusDB supports only INNER JOIN (no LEFT/OUTER JOIN) — and set operators (Union/Concat) — CamusDB has no UNION. These raise a translation or SQL error; project the shape with an explicit inner join or issue separate queries instead.

Query Result Cache

Opt a LINQ query into CamusDB's query result cache with WithCache(name). The provider injects the {cache=…} hint into the generated SQL, so an identical later query is served from the server's in-memory cache. As with the raw client, only single-table, autocommit reads are cacheable — a query with a join, or one inside an explicit transaction, reads live storage.

using CamusDB.EntityFrameworkCore;

// Cache with the server's default TTL
List<Order> recent = await ctx.Orders
    .Where(o => o.Status == 1)
    .OrderByDescending(o => o.Total)
    .Take(20)
    .WithCache("recent_orders")
    .ToListAsync();

// Per-entry TTL override and strict per-hit validation
List<Order> hot = await ctx.Orders
    .Where(o => o.Status == 1)
    .WithCache("hot_orders", ttl: TimeSpan.FromSeconds(30), strict: true)
    .ToListAsync();

Evict entries through the underlying CamusConnection (EvictCacheAsync / EvictAllCacheAsync).

Update

await using var ctx = new AppDbContext();

Robot robot = await ctx.Robots.FindAsync(id)
    ?? throw new InvalidOperationException("Not found");

robot.Price = 99.0;
await ctx.SaveChangesAsync();

Delete

await using var ctx = new AppDbContext();

Robot robot = await ctx.Robots.FindAsync(id)
    ?? throw new InvalidOperationException("Not found");

ctx.Robots.Remove(robot);
await ctx.SaveChangesAsync();

Migrations

The provider supports EF Core migrations for the following DDL operations:

Operation	Generated SQL
Create table	CREATE TABLE t (col TYPE [NOT NULL], ..., PRIMARY KEY (col1, ...))
Drop table	DROP TABLE t
Rename table	ALTER TABLE t RENAME TO new_name
Add column	ALTER TABLE t ADD COLUMN col TYPE [NOT NULL] [DEFAULT (value)]
Drop column	ALTER TABLE t DROP COLUMN col
Rename column	ALTER TABLE t RENAME COLUMN old TO new
Alter column nullability	ALTER TABLE t ALTER COLUMN col SET NOT NULL / DROP NOT NULL
Add check constraint	ALTER TABLE t ADD CONSTRAINT name CHECK (expr)
Drop check constraint	ALTER TABLE t DROP CONSTRAINT name
Create index	CREATE INDEX name ON t (col1, col2)
Create unique index	CREATE UNIQUE INDEX name ON t (col1, col2)
Drop index	ALTER TABLE t DROP INDEX name
Rename index	ALTER TABLE t RENAME INDEX old TO new
Raw SQL	passed through as-is

A CHECK constraint declared with ToTable(t => t.HasCheckConstraint(...)) is emitted as a table-level CONSTRAINT name CHECK (expr) inside CREATE TABLE (both via migrations and EnsureCreated), and can be added or dropped later with migrationBuilder.AddCheckConstraint / DropCheckConstraint. Changing a property's nullability (with the column type unchanged) maps to CamusDB's ALTER COLUMN … SET/DROP NOT NULL; DropCheckConstraint also drops a named NOT NULL constraint by name, since CamusDB resolves DROP CONSTRAINT against both.

The provider ships design-time services so the EF tooling can discover the provider automatically. No extra flags are needed:

dotnet ef migrations add InitialCreate
dotnet ef database update

Example migration using the supported operations:

public partial class AddStockColumn : Migration
{
    protected override void Up(MigrationBuilder migrationBuilder)
    {
        migrationBuilder.AddColumn<int>(
            name: "Stock",
            table: "products",
            type: "int64",
            nullable: false,
            defaultValue: 0);

        migrationBuilder.CreateIndex(
            name: "idx_products_name",
            table: "products",
            column: "Name",
            unique: true);

        migrationBuilder.AddCheckConstraint(
            name: "ck_products_stock",
            table: "products",
            sql: "Stock >= 0");
    }

    protected override void Down(MigrationBuilder migrationBuilder)
    {
        migrationBuilder.DropCheckConstraint(name: "ck_products_stock", table: "products");
        migrationBuilder.DropIndex(name: "idx_products_name", table: "products");
        migrationBuilder.DropColumn(name: "Stock", table: "products");
    }
}

Concurrency Tokens

The provider supports EF Core optimistic concurrency. When a tracked entity has a concurrency token, its previously-loaded value is added to the UPDATE's WHERE clause; a stale write matches zero rows on the server and the provider raises DbUpdateConcurrencyException.

[Timestamp] / IsRowVersion() — a byte[] row version. CamusDB has no server-side auto-version, so the provider generates a fresh, strictly-increasing token on every insert and update and sends it (stored as a BYTES column). No manual bookkeeping is required:

public class Doc
{
    public string Id      { get; set; } = "";
    public string Body    { get; set; } = "";
    [Timestamp]
    public byte[] Version { get; set; } = [];   // provider-managed row version
}

doc.Body = "edited";
await ctx.SaveChangesAsync();                    // throws DbUpdateConcurrencyException if stale

[ConcurrencyCheck] on a numeric column (short, int, long) — the application increments the version before SaveChanges():

public class Order
{
    public string Id      { get; set; } = "";
    public string Status  { get; set; } = "";
    [ConcurrencyCheck]
    public long Version   { get; set; }
}

order.Status = "shipped";
order.Version++;                                 // manual bump
await ctx.SaveChangesAsync();                    // throws DbUpdateConcurrencyException if stale

Note on MVCC vs. optimistic concurrency: the WHERE-clause check above is evaluated at write time, so a stale SaveChangesAsync fails immediately with DbUpdateConcurrencyException. This is distinct from CamusDB's MVCC write-write conflict detection between two open explicit transactions, which surfaces at commit time (CommitTransactionAsync). Use a concurrency token for application-level stale-update detection.

Provider Limitations

• No computed columns.
• No foreign key constraints.
• No LEFT/OUTER JOIN — CamusDB supports only INNER JOIN. Include/collection navigations and optional-reference joins do not translate; use an explicit inner join projection.
• No UNION/UNION ALL — LINQ Union/Concat do not translate; issue separate queries.
• ALTER COLUMN only supports toggling nullability (SET/DROP NOT NULL); changing a column's stored type requires dropping and recreating the column.
• CHECK conditions must be deterministic single-row predicates — no subqueries, aggregates, or volatile functions (now(), gen_uuid_v4/v7(), …); a violated check surfaces as a CamusException with code CADB0303 (wrapped in DbUpdateException under EF Core), and a NULL operand makes the predicate pass (SQL three-valued logic).
• array(T) columns map for long[], string[], double[], and bool[]. They are not indexable and have no SQL literal, so an array can only be written/read as a whole value — it cannot appear in a Where predicate or as a default/seed value.
• No decimal/exact-numeric store type — use double (float64), accepting binary floating-point rounding.
• Key CLR types must be one of: string, int, long, short, or Guid.
• [ConcurrencyCheck] is supported on short/int/long; [Timestamp]/IsRowVersion() is supported on byte[] (provider-managed). A stale write raises DbUpdateConcurrencyException.
• WithCache(...) only takes effect on single-table, autocommit reads; the hint is inert on queries with a join or run inside an explicit transaction (they read live storage).

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Run Tests

To run the unit tests, a CamusDB instance must be running locally. After starting it, run:

dotnet test -l "console;verbosity=normal" --filter "FullyQualifiedName~CamusDB.Client.Tests"

Contribution

CamusDB.Client is an open-source project, and contributions are heartily welcomed! Whether you are looking to fix bugs, add new features, or improve documentation, your efforts and contributions will be appreciated. Check out the CONTRIBUTING.md file for guidelines on how to get started with contributing to CamusDB.Client.

License

CamusDB.Client is released under the MIT License.