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fix(export): stream chunks incrementally for database dumps to prevent OOM (#59) #316

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fix(export): stream chunks incrementally for database dumps to prevent OOM (#59) #316

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95 changes: 59 additions & 36 deletions src/export/dump.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -16,54 +16,77 @@ export async function dumpDatabaseRoute(
)

const tables = tablesResult.map((row: any) => row.name)
let dumpContent = 'SQLite format 3\0' // SQLite file header

// Iterate through all tables
for (const table of tables) {
// Get table schema
const schemaResult = await executeOperation(
[
{
sql: `SELECT sql FROM sqlite_master WHERE type='table' AND name='${table}';`,
},
],
dataSource,
config
)
const encoder = new TextEncoder()
const stream = new ReadableStream({
async start(controller) {
try {
controller.enqueue(encoder.encode('SQLite format 3\0'))

if (schemaResult.length) {
const schema = schemaResult[0].sql
dumpContent += `\n-- Table: ${table}\n${schema};\n\n`
}
for (const table of tables) {
const schemaResult = await executeOperation(
[
{
sql: `SELECT sql FROM sqlite_master WHERE type='table' AND name='${table}';`,
},
],
dataSource,
config
)

// Get table data
const dataResult = await executeOperation(
[{ sql: `SELECT * FROM ${table};` }],
dataSource,
config
)
if (schemaResult.length) {
const schema = schemaResult[0].sql
controller.enqueue(
encoder.encode(`\n-- Table: ${table}\n${schema};\n\n`)
)
}

for (const row of dataResult) {
const values = Object.values(row).map((value) =>
typeof value === 'string'
? `'${value.replace(/'/g, "''")}'`
: value
)
dumpContent += `INSERT INTO ${table} VALUES (${values.join(', ')});\n`
}
// Stream table rows with cursor pagination to avoid worker OOM
let offset = 0
const chunkSize = 1000
while (true) {
const dataResult = await executeOperation(
[{ sql: `SELECT * FROM ${table} LIMIT ${chunkSize} OFFSET ${offset};` }],
dataSource,
config
)

dumpContent += '\n'
}
if (!dataResult || dataResult.length === 0) break

// Create a Blob from the dump content
const blob = new Blob([dumpContent], { type: 'application/x-sqlite3' })
let chunkSql = ''
for (const row of dataResult) {
const values = Object.values(row).map((value) =>
typeof value === 'string'
? `'${value.replace(/'/g, "''")}'`
: value
)
chunkSql += `INSERT INTO ${table} VALUES (${values.join(', ')});\n`
}
controller.enqueue(encoder.encode(chunkSql))

offset += dataResult.length
if (dataResult.length < chunkSize) break

// Cooperative event-loop yielding
await new Promise((r) => setTimeout(r, 0))
}

controller.enqueue(encoder.encode('\n'))
}

controller.close()
} catch (err) {
controller.error(err)
}
},
})

const headers = new Headers({
'Content-Type': 'application/x-sqlite3',
'Content-Disposition': 'attachment; filename="database_dump.sql"',
})

return new Response(blob, { headers })
return new Response(stream, { headers })
} catch (error: any) {
console.error('Database Dump Error:', error)
return createResponse(undefined, 'Failed to create database dump', 500)
Expand Down