A retried `upsert` inserts a key that a concurrent writer already inserted

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
54/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Active
Tech stack
python, sqlite
Domain
backend, database, databases

Research direction

Start by tracing the upsert commit retry and _FastAppendFiles._validate_concurrency; the issue says that path currently fails to detect a concurrent insert. Reproduce the two-writer example with the supplied SQLite catalog and PyArrow table, then compare the behavior with version 0.11.1. Done means a retry does not leave duplicate keys, and concurrent add_files does not register the same file twice.

Written by the indexing model from the issue text.

Description

kind:bug
Apache Iceberg version

0.12.0 (latest release)

Please describe the bug 🐞

Currently, a commit retry replays the upsert's append, and _FastAppendFiles._validate_concurrency checks nothing, so a key another writer inserted after the read is inserted a second time. 0.11.1 raises CommitFailedException here.

import tempfile
import pyarrow as pa
from pyiceberg.catalog.sql import SqlCatalog
from pyiceberg.schema import Schema
from pyiceberg.types import LongType, NestedField, StringType

cat = SqlCatalog("c", uri="sqlite:///:memory:", warehouse=f"file://{tempfile.mkdtemp()}")
cat.create_namespace("ns")
schema = Schema(NestedField(1, "k", LongType(), required=True), NestedField(2, "v", StringType()), identifier_field_ids=[1])
t = cat.create_table("ns.t", schema=schema)
row = lambda k, v: pa.Table.from_pylist([{"k": k, "v": v}], schema=schema.as_arrow())
t.append(row(1, "a"))

a = cat.load_table("ns.t")
b = cat.load_table("ns.t")
b.upsert(row(2, "b"))
a.upsert(row(2, "a"))
# Commit failed due to a concurrent update, retrying (1/4) in 106 ms
print(sorted(cat.load_table("ns.t").scan().to_arrow().to_pylist(), key=str))
# [{'k': 1, 'v': 'a'}, {'k': 2, 'v': 'a'}, {'k': 2, 'v': 'b'}], should hold k 2 once

Two writers calling add_files on the same file register it twice the same way, and every row in it reads back twice.

tested on pyiceberg 0.12.0 and main

Willingness to contribute
  • I can contribute a fix for this bug independently
  • I would be willing to contribute a fix for this bug with guidance from the Iceberg community
  • I cannot contribute a fix for this bug at this time
Dominant language
Python
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