399534e7af
Adds SqlWriter: a pyodbc-backed writer that dedup-inserts into dbo.SyncQueue (IF NOT EXISTS guarded by UX_SyncQueue_Dedup), invokes dbo.usp_SyncApply, and reports applied SourceLogIDs. Connection is opened with autocommit=True per the controller revision: usp_SyncApply manages its own transaction internally (BEGIN/ROLLBACK), and an outer pyodbc transaction would conflict on ROLLBACK (SQL error 266). The dedup IF NOT EXISTS...INSERT is a single atomic statement. Integration test self-cleans via SourceFile='sqlw_test.accdb' marker; conn_str comes from the gitignored config.yaml (no hardcoded creds). Co-Authored-By: Claude <noreply@anthropic.com>
96 lines
3.5 KiB
Python
96 lines
3.5 KiB
Python
"""SQL-side writer for the Access -> SQL Server sync.
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SqlWriter owns the pyodbc connection used to (a) dedup-insert rows into
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``dbo.SyncQueue``, (b) invoke ``dbo.usp_SyncApply`` to drain the queue, and
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(c) report which SourceLogIDs have been applied.
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The connection is opened with ``autocommit=True`` on purpose. ``usp_SyncApply``
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manages its own transaction internally (BEGIN TRAN ... ROLLBACK on error); if
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the caller held an outer implicit transaction, the proc's ROLLBACK would
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cascade and raise SQL error 266. The dedup ``IF NOT EXISTS ... INSERT`` is a
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single statement that is atomic under autocommit, so no explicit transaction is
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needed on the write path either.
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"""
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from __future__ import annotations
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from dataclasses import dataclass
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import pyodbc
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@dataclass
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class QueueRow:
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"""A single staged change to enqueue into ``dbo.SyncQueue``."""
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source_file: str
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source_table: str
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record_id: str
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target_schema: str
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target_table: str
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source_log_id: int
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operate_type: str
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row_data: str | None
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class SqlWriter:
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"""Writes to SyncQueue and drives the apply proc over a pyodbc connection."""
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def __init__(self, conn_str: str, queue_table: str = "dbo.SyncQueue"):
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self.conn_str = conn_str
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self.queue_table = queue_table
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# autocommit=True: usp_SyncApply manages its own transaction internally.
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# An outer pyodbc transaction would conflict on ROLLBACK (SQL error 266).
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self._conn = pyodbc.connect(conn_str, autocommit=True)
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def insert_queue_row(self, row: QueueRow) -> None:
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"""Idempotently enqueue ``row`` (dedup on SourceFile/Table/LogID).
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``IF NOT EXISTS ... INSERT`` is a single statement, atomic under
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autocommit. The unique index UX_SyncQueue_Dedup is the DB backstop.
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"""
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# IF NOT EXISTS and the VALUES list each carry their own ? markers;
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# pyodbc binds them positionally, so the 3 dedup keys are supplied
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# twice (once for the EXISTS check, once for the INSERT).
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cur = self._conn.cursor()
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cur.execute(
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"IF NOT EXISTS (SELECT 1 FROM dbo.SyncQueue "
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"WHERE SourceFile=? AND SourceTable=? AND SourceLogID=?) "
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"INSERT dbo.SyncQueue(SourceFile,SourceTable,SourceLogID,"
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"TargetSchema,TargetTable,RecordID,OperateType,RowData,Status) "
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"VALUES (?,?,?,?,?,?,?,?, 'pending')",
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row.source_file,
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row.source_table,
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row.source_log_id,
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row.source_file,
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row.source_table,
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row.source_log_id,
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row.target_schema,
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row.target_table,
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row.record_id,
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row.operate_type,
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row.row_data,
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)
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# autocommit: statement already committed.
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def call_apply(self, max_retries: int) -> None:
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"""Drain the pending queue via the stored procedure.
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``usp_SyncApply`` flips rows to ``applied`` (or ``error`` after retries).
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"""
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cur = self._conn.cursor()
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cur.execute("EXEC dbo.usp_SyncApply ?", max_retries)
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def applied_log_ids(self, source_file: str) -> list[int]:
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"""Return applied SourceLogIDs for ``source_file`` in ascending order."""
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cur = self._conn.cursor()
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cur.execute(
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"SELECT SourceLogID FROM dbo.SyncQueue "
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"WHERE SourceFile=? AND Status='applied' ORDER BY SourceLogID",
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source_file,
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)
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return [r[0] for r in cur.fetchall()]
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def close(self) -> None:
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"""Close the underlying pyodbc connection."""
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self._conn.close()
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