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electric-sql
Bug: [pglite-tools] pg dump throw error when fs is opfs-ahp
Summary
When using pgDump in web worker and fs is opfs-ahp,the function throw Error: pg_dump failed with exit code 1.
Detail
Error Message:
Error: pg_dump failed with exit code 1.
Error message: could not find a "pg_dump" to execute
pg_dump: error: query failed: unexpected response from server; first received character was "R"
pg_dump: detail: Query was: SELECT pg_catalog.set_config('search_path', '', false);
at Mt (pg_dump.ts:193:11)
at async init (opfs-worker-pg-dump.js:52:20)
Example
Here is the example repo: https://github.com/lastsunday/pglite/tree/opfs_pg_dump_test
import { PGlite } from "../dist/index.js";
import { worker } from "../dist/worker/index.js";
import { pgDump } from "./pglite-tools/pg_dump.js";
worker({
async init() {
const pg = new PGlite("opfs-ahp://my-test-db2");
// If you want run any specific setup code for the worker process, you can do it here.
try {
console.log("Starting...");
const start = performance.now();
console.log("Waiting for ready...");
await pg.waitReady;
console.log("Ready! Took", performance.now() - start, "ms");
console.log("Creating table...");
await pg.exec(`
CREATE TABLE IF NOT EXISTS test (
id SERIAL PRIMARY KEY,
name TEXT
);
`);
console.log("Inserting data...");
await pg.exec("INSERT INTO test (name) VALUES ('test');");
console.log("Selecting data...");
const res = await pg.exec(`
SELECT * FROM test;
`);
console.log(res);
// Transaction example:
console.log("Transaction example...");
await pg.transaction(async (tx) => {
await tx.exec("INSERT INTO test (name) VALUES ('test2');");
await tx.exec("INSERT INTO test (name) VALUES ('test3');");
});
console.log("Selecting data...");
const res2 = await pg.exec(`
SELECT * FROM test;
`);
console.log(res2);
console.log('Dumping database...')
const dump = await pgDump({ pg })
console.log(dump)
} catch (e) {
console.error(e);
}
return pg;
},
});
console.log("Worker process started");
<!doctype html>
<html>
<head>
<title>PGlite Worker Example</title>
<link rel="stylesheet" href="./styles.css" />
<script src="./utils.js"></script>
<script type="importmap">
{
"imports": {
"@electric-sql/pglite/worker": "../dist/worker/index.js"
}
}
</script>
</head>
<body>
<h1>PGlite OPFS PG Dump Example</h1>
<div class="script-plus-log">
<div class="scripts">
<h2>Worker Thread - <code>opfs-worker-pg-dump.js</code></h2>
<div class="script" rel="./opfs-worker-pg-dump.js"></div>
<h2>Main Thread</h2>
<script type="module">
import { PGliteWorker } from "@electric-sql/pglite/worker";
const pg = new PGliteWorker(
new Worker(new URL("./opfs-worker-pg-dump.js", import.meta.url), {
type: "module",
})
);
</script>
</div>
<div id="log"></div>
</div>
</body>
</html>
@lastsunday Thank you for this! We will address this issue as soon as time allows.
While we fix this, here is a workaround: clone your main pglite instance to another instance that doesn't use persistence, and dump that one instead:
it('specify datadir: should dump a database with tables and data', async () => {
const pg = await PGlite.create({
dataDir: '/tmp/pg_dump',
})
// Create test tables and insert data
await pg.exec(`
CREATE TABLE test1 (
id SERIAL PRIMARY KEY,
name TEXT
);
INSERT INTO test1 (name) VALUES ('test1-row1');
CREATE TABLE test2 (
id SERIAL PRIMARY KEY,
value INTEGER
);
INSERT INTO test2 (value) VALUES (42);
`)
const pgMem = await pg.clone()
const dump = await pgDump({ pg: pgMem })
const content = await dump.text()
// Check for table creation
expect(content).toContain('CREATE TABLE public.test1')
expect(content).toContain('CREATE TABLE public.test2')
// Check for data inserts
expect(content).toContain('INSERT INTO public.test1')
expect(content).toContain("'test1-row1'")
expect(content).toContain('INSERT INTO public.test2')
expect(content).toContain('42')
})
It sound not the perfect way and just a temporary solution for the small data record in pglite instance. Maybe occur out off memory error when the main pglite instance data is huge and execute the clone method.