Run DEALLOCATE ALL; after pg_dump (#563)

* run DEALLOCATE ALL after pgdump


---------

Co-authored-by: tudor <tudor@swisstch.com>

Author: copiltembel

.changeset/moody-knives-allow.md

@@ -0,0 +1,5 @@
+---
+'@electric-sql/pglite-tools': patch
+---
+
+Run a DEALLOCATE ALL after each pg_dump to cleanup the prepared statements.

packages/pglite-tools/README.md

@@ -12,6 +12,8 @@ npm install @electric-sql/pglite-tools
 
 pg_dump is a tool for dumping a PGlite database to a SQL file, this is a WASM build of pg_dump that can be used in a browser or other JavaScript environments. You can read more about pg_dump [in the Postgres docs](https://www.postgresql.org/docs/current/app-pgdump.html).
 
+Note: pg_dump will execute `DEALLOCATE ALL;` after each dump. Since this is running on the same (single) connection, any prepared statements that you have made before running pg_dump will be affected.
+
 ### Options
 
 - `pg`: A PGlite instance.

packages/pglite-tools/src/pg_dump.ts

@@ -182,6 +182,8 @@ export async function pgDump({
     args: [...(args ?? []), ...baseArgs],
   })
 
+  pg.query(`DEALLOCATE ALL;`)
+
   if (exitCode !== 0) {
     throw new Error(
       `pg_dump failed with exit code ${exitCode}. \nError message: ${errorMessage}`,

packages/pglite-tools/tests/pg_dump.test.ts

@@ -14,6 +14,21 @@ describe('pgDump', () => {
     expect(content).toContain('PostgreSQL database dump')
   })
 
+  it('should dump an empty database multiple times', async () => {
+    const pg = await PGlite.create()
+
+    for (let i = 0; i < 5; i++) {
+      const fileName = `dump_${i}.sql`
+      const dump = await pgDump({ pg, fileName })
+
+      expect(dump).toBeInstanceOf(File)
+      expect(dump.name).toBe(fileName)
+
+      const content = await dump.text()
+      expect(content).toContain('PostgreSQL database dump')
+    }
+  })
+
   it('should dump a database with tables and data', async () => {
     const pg = await PGlite.create()