allowWrites is no longer inert: SqlDriver implements IWritable, default off.
- Gates (outermost first): node Writable + WriteOperate (server), driver
allowWrites, the tag's own TagConfig "writable": true (strict JSON boolean;
anything else refuses the tag, and the deploy gate says why), and a model that
names exactly one row — KeyValue, or WideRow by where-pair. topByTimestamp and
Query are BadNotWritable.
- SqlWritePlanner: the only statement a write can become is
UPDATE <table> SET <value col> = @v WHERE <key col> = @k, built from the
catalog-gate-canonical identifiers (dialect-quoted) with value and key bound;
value-before-key marker order so positional ODBC binds correctly. No authored
write SQL, INSERT, UPSERT or procedure.
- Executed in a transaction that commits only when exactly one row was touched:
0 rows -> BadNoData (never inserts), >1 -> rolled back, BadConfigurationError,
unknown count -> rolled back, BadNotSupported. Bounded by operationTimeout;
provider errors -> BadCommunicationError; health untouched.
- Discovery advertises Operate only where a write could succeed.
- AdminUI: driver form's Allow writes switch is live; tag editor gains a
per-tag write switch; model validates writable strictly (parity corpus).
- Factory no longer warns "allowWrites ignored"; it logs whether writes are on.
- Tests: SqlWriteTests (planner SQL/bind order/injection/coercion, every gate,
readback, absent key, two-row rollback, gate-rejected tag, discovery);
MySqlReadTests write legs against InnoDB (keyed row only, two-row rollback,
server-side grant refusal, default-off). Seed adds a setpoints table and the
one UPDATE grant.
(lmxopcua#753)
Claude-Session: https://claude.ai/code/session_01GT67AEHd2Acv1YPwGfXEoV
SqlProvider.MySql is now a constructed backend instead of a reserved name.
- MySqlDialect (Driver.Sql.Dialect): MySqlConnector 2.6.2 (MIT, fully managed,
no vulnerable packages), backtick quoting with MySQL's 64-char / no-trailing-
space rules, information_schema catalog SQL with the database as the schema
(system databases excluded, aliases pinned), trailing LIMIT, a type map that
also reads the reader-side spellings (INT UNSIGNED -> UInt32, BOOL -> Boolean).
- SqlDialects: the one provider -> dialect map. The factory, the Test Connect
probe and the browse picker each carried their own switch (and drifted once);
they now all read this, and their refusals list the supported/reserved sets
from it.
- AdminUI driver form offers MySql.
- Tests: MySqlDialectTests (golden quoting/catalog/type map/planner SQL); the
provider-gate tests in factory, probe, browser and form now treat MySql as
supported and Odbc as the reserved control. MySqlReadTests + Docker/mysql
(throwaway mysql:8.4, SELECT-only login): liveness, KV/wide-row/topByTimestamp,
INT keys vs authored text, case folding against case-sensitive table names,
catalog rejection, browse walk, factory+probe, named query with a bound
parameter, and a writing stored function whose effect the rolled-back
transaction discards.
(lmxopcua#753)
Claude-Session: https://claude.ai/code/session_01GT67AEHd2Acv1YPwGfXEoV
Joseph Doherty