conductor

index.js (2128B)

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 // src/lib/db/index.js - database driver selection
 //
 // Every driver exposes the same surface:
 //   all(sql, params)   -> array of rows
 //   get(sql, params)   -> first row, or undefined
 //   run(sql, params)   -> { changes, lastInsertId }
 //   exec(sql)          -> no result, for DDL, bind markers are not parsed
 //   transaction(fn)    -> fn receives a scoped handle, nesting uses savepoints
 //   close()
 //
 // Params is an object, and queries use named {name} markers which each driver
 // compiles to its own placeholder syntax. See query.js.
 //
 //   db.get('SELECT * FROM tasks WHERE job_id = {job}', { job: jobId })
 //
 // Portability rules that apply to every query written against this layer:
 //   - named {name} markers only, never ? or $n directly
 //   - timestamps are epoch milliseconds, produced by Date.now()
 //   - booleans are stored as 0 and 1, never a native boolean type
 //   - no dialect specific functions; keep those behind a driver method
 //   - no reliance on lastInsertId; identifiers are generated by the caller
 //   - no upsert syntax; ON DUPLICATE KEY and ON CONFLICT are not portable,
 //     so do the read and the write explicitly inside a transaction
 //
 // One behavioural note on run().changes: mysql counts rows actually changed,
 // while sqlite and postgres count rows matched. An UPDATE that writes a value
 // identical to the current one therefore reports 0 on mysql and 1 elsewhere.
 // The conditional claim pattern used by the scheduler always writes a
 // different state, so it is unaffected; avoid depending on changes for an
 // update that may be a no-op.
 
 import { openSqlite } from './sqlite.js';
 import { openMysql } from './mysql.js';
 import { openPostgres } from './postgres.js';
 
 export { DIALECTS, dialectFromUrl } from './dialect.js';
 
 export async function openDatabase(cfg) {
   switch (cfg.database.dialect) {
     case 'mysql': return openMysql(cfg);
     case 'postgres': return openPostgres(cfg);
     case 'sqlite': return openSqlite(cfg);
     default: throw new Error(`unknown database dialect: ${cfg.database.dialect}`);
   }
 }
 
 export { runMigrations } from './migrate.js';