---
type: concept
x-llmwiki:
  schemaVersion: "0.1"
  contentHash: dab99452f679d5f7df660c9b1eb3ba911a456c70f955df69f8feac0c9e519628
  pageDirectory: concepts
  sources:
    - delta_concurrent_delete_read-error-condition-databricks-on-aws.md
  confidence: 0.9
  provenanceState: extracted
  freshnessStatus: unverified
  aliases:
    - partition-level-conflict-hints-in-delta-lake
    - PCHIDL
  citations:
    - file: delta_concurrent_delete_read-error-condition-databricks-on-aws.md
title: Partition-Level Conflict Hints in Delta Lake
description: A mechanism where partition hints can narrow the scope of concurrent delete/read conflicts to specific partitions, but can still fail when those partitions are affected by concurrent deletions.
tags:
  - delta-lake
  - partitioning
  - concurrency
timestamp: "2026-06-18T11:52:59.810Z"
---

# Partition-Level Conflict Hints in Delta Lake

**Partition-Level Conflict Hints** are read-time filters or partition predicates that Delta Lake uses to narrow the scope of a transaction’s reads to specific partitions. When a concurrent delete operation removes data from those partitions, Delta Lake can detect the conflict more precisely and report it as a `DELTA_CONCURRENT_DELETE_READ` error with a subcondition that identifies whether a partition hint was present. ^[delta_concurrent_delete_read-error-condition-databricks-on-aws.md]

## The DELTA_CONCURRENT_DELETE_READ Error

The error `DELTA_CONCURRENT_DELETE_READ` (SQLSTATE: 2D521) occurs when a transaction reads data from a table, and a concurrent operation deletes data from that same table (committed at a later version) that the transaction had read. The error includes a subcondition that provides details about the nature of the conflict and suggested remediation. ^[delta_concurrent_delete_read-error-condition-databricks-on-aws.md]

## Subconditions Related to Partition Hints

Several subconditions of `DELTA_CONCURRENT_DELETE_READ` are directly related to whether a partition-level hint was used by the reading transaction.

### WITH_PARTITION_HINT

> The concurrent operation deleted data in the partition `<partitionValues>` that was read by this operation. Please retry the operation. ^[delta_concurrent_delete_read-error-condition-databricks-on-aws.md]

This subcondition indicates that the read transaction specified a partition hint (for example, a `WHERE` clause on a partition column) and the concurrent deletion affected one or more of those exact partitions. The partition values are included in the error message.

### WITHOUT_HINT

> The concurrent operation deleted data that was read by this operation. Please retry the operation. ^[delta_concurrent_delete_read-error-condition-databricks-on-aws.md]

This subcondition indicates that the read transaction did **not** specify a partition hint. Delta Lake could not narrow the conflict detection to a specific partition, so the entire read scope was considered.

### PARTITIONED_TABLE_WITHOUT_MERGE_SOURCE

> Row-level conflict detection could not be performed on this partitioned table. Please retry the operation. ^[delta_concurrent_delete_read-error-condition-databricks-on-aws.md]

This subcondition occurs when a partitioned table is involved but the merge operation’s source or predicate does not allow row-level conflict detection. It is not a partition hint per se, but it underscores the importance of providing sufficient predicates for Delta Lake to resolve conflicts efficiently.

## Related Subconditions on Read Scope

While not exclusively about partition hints, the following subconditions highlight the value of narrowing reads (which partition hints accomplish) to avoid whole-table conflicts:

- **EMPTY_READ_PREDICATES**: The transaction did not include any filters and read the entire table, conflicting with the concurrent deletion. The guidance is to add filters to narrow the data scope. ^[delta_concurrent_delete_read-error-condition-databricks-on-aws.md]
- **WHOLE_TABLE_READ**: The transaction attempted to read the entire table. Again, adding filters is recommended. ^[delta_concurrent_delete_read-error-condition-databricks-on-aws.md]

Both can be mitigated by using partition-level hints (i.e., partition predicates) so that Delta Lake only reads the relevant partitions and can detect conflicts at a finer granularity.

## Best Practice

To reduce the likelihood of `DELTA_CONCURRENT_DELETE_READ` errors and to benefit from partition-level conflict hints, always include partition filters in your read queries (e.g., `WHERE partition_col = value`). This allows Delta Lake to confine its read set and detect conflicts on a per-partition basis rather than against the whole table. ^[delta_concurrent_delete_read-error-condition-databricks-on-aws.md]

## Sources

- delta_concurrent_delete_read-error-condition-databricks-on-aws.md

# Citations

1. [delta_concurrent_delete_read-error-condition-databricks-on-aws.md](/references/delta_concurrent_delete_read-error-condition-databricks-on-aws-d0015916.md)
