dalgo2mysql

MySQL-specific DALgo driver. Wraps github.com/dal-go/dalgo2sql to provide the dal.DB surface, and adds MySQL-native implementations of:

• dbschema.SchemaReader — schema introspection via information_schema scoped to the connected database (DATABASE())
• ddl.Applier — MySQL-flavored CREATE TABLE / CREATE INDEX / DROP TABLE / ALTER TABLE
• dal.ConcurrencyAware — advertises SupportsConcurrentConnections() = true (MySQL supports concurrent connections from multiple goroutines and processes, unlike SQLite which serializes writers)

Constructor usage

import (
    "github.com/dal-go/dalgo/dal"
    "github.com/dal-go/dalgo2mysql"
    "github.com/dal-go/dalgo2sql"
)

// Minimal — no per-collection primary-key configuration.
db, err := dalgo2mysql.NewDatabase("user:pass@tcp(127.0.0.1:3306)/mydb?parseTime=true")

// With per-collection recordset options (required for Insert/Get/Delete with map[string]any data):
db, err := dalgo2mysql.NewDatabaseWithOptions(dsn, dal.NewSchema(nil, nil),
    dalgo2sql.DbOptions{
        Recordsets: map[string]*dalgo2sql.Recordset{
            "widgets": dalgo2sql.NewRecordset("widgets", dalgo2sql.Table,
                []dal.FieldRef{dal.Field("id")}),
        },
    })
if err != nil {
    return err
}
defer db.Close()

The DSN is in go-sql-driver/mysql format. Always include ?parseTime=true so DATETIME/TIMESTAMP columns scan into time.Time rather than []byte.

Type mapping

dbschema.Type	MySQL column type
String	VARCHAR(255) (or VARCHAR(n) when Length is set)
Int	BIGINT
Float	DOUBLE
Bool	BOOLEAN (stored as tinyint(1))
Time	DATETIME
Decimal	DECIMAL (or DECIMAL(total, scale) when Precision is set)
Bytes	BLOB

String always maps to VARCHAR, never TEXT: a VARCHAR(255) can serve as a PRIMARY KEY or index member under utf8mb4 on InnoDB, whereas TEXT/BLOB columns cannot be indexed without an explicit prefix length. This matters for the conventional id primary key, which is a String.

On introspection MySQL reports BOOLEAN columns as tinyint; dbschemaTypeFromMySQL maps tinyint back to dbschema.Bool.

Running the tests

The tests that touch a live database are gated on the DALGO2MYSQL_TEST_DSN environment variable. When it is not set, those tests are skipped so plain CI passes without a database.

Start a local MySQL 8.4 server (Docker). lower_case_table_names=0 keeps identifiers case-sensitive and case-preserving:

docker run -d \
  --name mysql84 \
  -e MYSQL_USER=ovdb \
  -e MYSQL_PASSWORD=ovdb \
  -e MYSQL_DATABASE=ovdb \
  -e MYSQL_ROOT_PASSWORD=ovdb \
  -p 13306:3306 \
  mysql:8.4 --lower_case_table_names=0

Then run the tests:

DALGO2MYSQL_TEST_DSN='ovdb:ovdb@tcp(127.0.0.1:13306)/ovdb?parseTime=true' \
    go test ./... -count=1 -v

MySQL driver: github.com/go-sql-driver/mysql (pure Go, CGO_ENABLED=0)

This package uses github.com/go-sql-driver/mysql — a pure-Go MySQL driver exposed through the standard database/sql interface (driver name "mysql"). No C toolchain is required; the package compiles with CGO_ENABLED=0.

Placeholder dialect

MySQL uses ? positional parameter markers, which is exactly dalgo2sql's default (PlaceholderQuestion). Unlike dalgo2postgres (which forces PlaceholderDollar for $1, $2, …), dalgo2mysql leaves dalgo2sql.DbOptions.Placeholder at its zero value.

Identifier case: preserved, not folded

Unlike PostgreSQL — which folds unquoted identifiers to lower case — MySQL with lower_case_table_names=0 preserves identifier case: table names are case-sensitive, and column names are case-insensitive but case-preserving. dalgo2mysql back-tick quotes identifiers in DDL (escaping embedded back-ticks by doubling) but does not lower-case them, so the bare identifiers that dalgo2sql's DML and dalgo's structured-query rendering emit already match the back-tick-quoted DDL. No case-folding workaround is needed.

DDL is non-transactional

MySQL implicitly commits the current transaction before and after every DDL statement (CREATE / DROP / ALTER), so schema changes cannot be rolled back atomically. SupportsTransactionalDDL() returns false (this differs from dalgo2postgres, which returns true). A multi-statement CreateCollection or AlterCollection that fails midway leaves earlier statements applied; callers that need clean recovery should drop the affected table.