MariaDB provider

Use nextorm.mariadb for MariaDB 10.4+; it reuses the MySQL rendering and adds the INTERSECT ALL/EXCEPT ALL set-operation variants.

Prerequisites: Provider overview · MySQL

Overview

MariaDbDataContext (src/nextorm.mariadb/MariaDbDataContext.cs) derives from MySqlDataContext, so it uses the same MySqlConnector driver and the same connection and parameter handling. It returns Instance from its Dialect property.

MariaDbDialect (src/nextorm.mariadb/MariaDbDialect.cs) derives from MySqlDialect and changes the capability set: INTERSECT ALL and EXCEPT ALL are supported by MariaDB 10.4 and later, so SupportsIntersectExceptAll is true; MariaDB 10.3+ renders the window percentiles percentile_cont/percentile_disc (... within group (order by ...) over (...)), so SupportsPercentileWindow is true; the same analytic shape backs SqlFunctions.MySql.median(value).Over(...) (rendered percentile_cont(0.5) within group (order by value) over (...), one row per input row, partition-only window), while the generic SqlFunctions.MySql.percentile has no MariaDB spelling and throws NotSupportedException; and UPDATE ... RETURNING is enabled only when an explicit server version 13.0+ is configured (SupportsUpdateReturning). It also keeps the arbitrary-value aggregate any_agg gated off, because MariaDB has no ANY_VALUE in 10.4–12.x (the SQL-2023 T626 feature is still pending, targeted for 13.2). Everything else (parameters, quoting, concat, coalesce, paging, aggregate names, the if(...) spelling of the portable iif) is inherited unchanged.

Registering the provider

Two overloads are available on DataContextBuilder (src/nextorm.mariadb/DI/MariaDbDataContextOptionsBuilderExtensions.cs):

using NextORM.Core;
using NextORM.MariaDb;

var builder = new DataContextBuilder()
    .UseMariaDb("Server=localhost;Port=3306;Database=app;User ID=app;Password=secret");

using var ctx = builder.CreateDataContext();   // IDataContext

You can also construct the context directly:

using NextORM.Core;
using NextORM.MariaDb;

using IDataContext ctx = new MariaDbDataContext(
    "Server=localhost;Database=app;User ID=app;Password=secret", new DataContextBuilder());

Server version

The dialect can be pinned to the server version, which gates UPDATE ... RETURNING and the bulk Returning* terminals. Configuration is explicit — nextorm never probes the live server. Pass the version with the context constructor's Version parameter. Unlike PostgreSQL, an unset version does not enable the feature: without an explicit 13.0+ the Returning() terminal of an UPDATE and a bulk Returning* call reject with NotSupportedException. Single-row insert and delete RETURNING are unchanged (MariaDB rejects them as before), and the ANY_VALUE gate (any_agg, targeted for 13.2) is also unchanged. Bulk Returning* is supported on 13.0+ and refused below; the live certification runs on mariadb:11.4, so it covers the refusal arm.

// Explicit 13.0+: `UPDATE ... RETURNING` is enabled.
using var ctx = new MariaDbDataContext(
    "Server=localhost;Database=app;...", new DataContextBuilder(), new Version(13, 0));

The same explicit version also gates the native functions MariaDB added after 11.4. Each is emitted only at or above its own minimum; an unversioned context (the two-argument constructor) refuses it with NotSupportedException at translation/preparation rather than emitting SQL the server rejects:

Member	Native form	Minimum
`SqlFunctions.MySql.months_between(a, b)`	`months_between(...)`	12.2.1
`SqlFunctions.MySql.to_date(value, format)`	`to_date(...)`	12.3
`SqlFunctions.MySql.to_number(value, format)`	`to_number(...)`	12.2 family, enforced 12.2.1
`SqlFunctions.Sql.gen_random_uuid()`	`uuid_v4()`	11.7
`SqlFunctions.Sql.uuidv7()`	`uuid_v7()`	11.7

These are function minima, not a raised provider floor: the package still supports MariaDB 10.4+ and add_months/to_char/the rest of the catalogue keep their own availability. The MariaDB-11.4 baseline names (add_months, to_char, nvl, the JSON family, sequences) are not version-gated.

Unlike PostgreSQL, MariaDB imposes no one-version-per-concrete-context-type guard: each context carries its own dialect instance and capability predicate, so the same concrete context type may be built with different versions. A strongly typed subclass is still a convenient way to pin one version:

public sealed class MariaDb130DataContext : MariaDbDataContext
{
    public MariaDb130DataContext(string connectionString, DataContextBuilder builder)
        : base(connectionString, builder, new Version(13, 0)) { }
}

Set operations

ctx.From<ISimpleEntity>().Select(x => x.Id).IntersectAll(ctx.From<ISimpleEntity>().Select(x => x.Id));
ctx.From<ISimpleEntity>().Select(x => x.Id).ExceptAll(ctx.From<ISimpleEntity>().Select(x => x.Id));

select id
 from simple_entity
 intersect all
select id
 from simple_entity

Bulk insert

MariaDB shares the MySQL implementation, so the native path is MySqlBulkCopy (a LOAD DATA LOCAL INFILE load) and it needs AllowLoadLocalInfile=true on the connection string plus the server variable @@GLOBAL.local_infile=1, read with a read-only preflight. nextorm never enables either one; without them Auto falls back only when the portable path honours the whole request and Native refuses by name.

Identity and duplicates follow MySQL: KeepIdentity writes the explicit identity column under a scoped NO_AUTO_VALUE_ON_ZERO guard, and IgnoreDuplicates is ConflictOption.Ignore on the native load or INSERT IGNORE on the portable statement.
CheckConstraints=false is honoured through scoped session controls, snapshotted and restored on the same session even when the load fails; TableLock and FireTriggers stay refused.
KeepNulls=false needs a default-equivalent shape.
Returning* on the bulk path is version-gated. MariaDB honours it at an explicitly configured 13.0+ and refuses it below (unset or older) with a named NotSupportedException; single-row insert and delete RETURNING stay refused at every version, so read keys with CreateInsertBuilder there. The live certification runs on mariadb:11.4, so it exercises the refusal arm; the 13.0+ arm is certified offline for the rendered INSERT ... RETURNING SQL only.
DatabaseName renders db.table; ServerName is refused (no rerouting). Timeout is one whole-invocation budget; an expired budget is a TimeoutException and cancellation wins.

See Bulk insert.

Provider differences

MariaDB differs from MySQL in the set-operation capability, the window percentiles, the version-gated UPDATE ... RETURNING and the arbitrary-value aggregate:

Aspect	MariaDB
Parameter placeholder	`@name`
Concat	`concat(a, b)`
Coalesce	`coalesce`
Identifier quoting	backticks (as `t1`)
Derived table alias	required
`*ALL`	supported (MariaDB 10.4+)
`UPDATE ... RETURNING`	enabled only with an explicit server version 13.0+ (`SupportsUpdateReturning`); otherwise `NotSupportedException`
Server version	configured explicitly via the context `Version`
Text JSON	inherited from MySQL (`JSON_EXTRACT`/`JSON_SET`)
Session/info functions	inherited from MySQL (`current_user()`, `session_user()`, `schema()`, `database()`, `version()`)
Arbitrary-value aggregate	not supported (no `ANY_VALUE` in 10.4–12.x; pending MDEV-10426, targeted for 13.2)
Conditional function	inherited from MySQL (`iif(cond, a, b)` → `if(cond, a, b)`)
Window percentiles	`percentile_cont`/`percentile_disc` as `... within group (order by x) over (...)` (MariaDB 10.3+); analytic: one row per input row
Median (analytic)	`SqlFunctions.MySql.median(v).Over(...)` → `percentile_cont(0.5) within group (order by v) over (...)`: one row per input row; partition-only `OVER` (window `ORDER BY`/frame refused)
Generic percentile	not supported: `SqlFunctions.MySql.percentile(fraction, v)` throws `NotSupportedException("The percentile function is not supported by MariaDB.")`
Percentile fraction	`double` in `[0, 1]` (not a percentage), validated before rendering; an out-of-range or non-finite value throws `ArgumentOutOfRangeException`
Native functions	the `SqlFunctions.MySql` surface inherited from MySQL minus `uuid_to_bin`/`bin_to_uuid`, plus the MariaDB-only names (extended regexp, `nvl`/`nvl2`, `add_months`/`months_between`, `to_char`/`to_date`/`to_number`, `kdf`, `xxh3`/`xxh32`, `json_detailed`/`json_compact`, sequence access). `months_between`/`to_date`/`to_number` (12.2.1 / 12.3 / 12.2.1) and `xxh3`/`xxh32` (13.1) are version-gated: an unversioned context, or a server below the minimum, refuses them with `NotSupportedException` before any SQL is emitted
LOB streaming (`ToStream`/`ToTextReader`)	`NotSupportedException`

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