---
type: concept
x-llmwiki:
  schemaVersion: "0.1"
  contentHash: df120a4b030b0421109def0ebeb70be5903302969c34db767b8bd5e81b2cad07
  pageDirectory: concepts
  sources:
    - delta_concurrent_delete_read-error-condition-databricks-on-aws.md
  confidence: 0.95
  provenanceState: extracted
  freshnessStatus: unverified
  aliases:
    - delta_concurrent_delete_read-error
    - DELTA_CONCURRENT_DELETE_READ
    - DELTA_CONCURRENT_DELETE_READ Error
    - DELTA_CONCURRENT_DELETE_READ error
    - DELTA_CONCURRENT_DELETE_READ error condition
    - Delta Concurrent Delete Read Error
    - delta_concurrent_delete_read-error-class
    - DEC
    - Concurrent delete read error class
    - DELTA_CONCURRENT_DELETE_READ error class
    - DELTA_CONCURRENT_DELETE_READ - WHOLE_TABLE_REPLACE
  citations:
    - file: delta_concurrent_delete_read-error-condition-databricks-on-aws.md
title: DELTA_CONCURRENT_DELETE_READ Error
description: A transaction conflict error in Delta Lake on Databricks triggered when a concurrent operation deletes data that another transaction is reading.
tags:
  - databricks
  - delta-lake
  - error-handling
timestamp: "2026-06-19T18:24:05.161Z"
---

# DELTA_CONCURRENT_DELETE_READ Error

The **DELTA_CONCURRENT_DELETE_READ** error (SQLSTATE `2D521`) occurs when a concurrent write operation deletes or changes data that a parallel read transaction had already read from the same Delta table. Delta Lake detects this conflict during the commit phase and raises the error when automatic resolution fails. ^[delta_concurrent_delete_read-error-condition-databricks-on-aws.md]

## Error Message

When this error occurs, Delta Lake returns a message of the form:

```
Transaction conflict detected, a concurrent <operation> deleted data from table <tableName> (committed at version <version>) that this transaction read.
```

The error message also includes a more specific sub‑error subclass, which provides additional detail about the nature of the conflict and recommended remediation steps. ^[delta_concurrent_delete_read-error-condition-databricks-on-aws.md]

## Sub‑Error Subclasses

The `DELTA_CONCURRENT_DELETE_READ` error class contains multiple subclasses. Each subclass describes a distinct cause and action:

| Subclass | Description | Recommended Action |
|----------|-------------|-------------------|
| `ALLOTTED_TIME_EXCEEDED` | Row-level conflict resolution exceeded the allowed time. | Retry the operation. |
| `CHANGE_TYPE_COLUMN` | The table contains a column named `_change_type`, which conflicts with Change Data Feed (CDC) metadata columns. Row-level conflict detection is blocked. | Rename the column or disable CDC. |
| `EMPTY_READ_PREDICATES` | The transaction read the entire table without any filters, conflicting with concurrent deletion. | Add filters to narrow the data scope and retry. |
| `PARTITIONED_TABLE_WITHOUT_MERGE_SOURCE` | Row-level conflict detection could not be performed on this partitioned table. | Retry the operation. |
| `PREDICATES_NEED_REWRITE` | Filter predicates used by the transaction could not be applied for row-level conflict detection. | Retry the operation. |
| `PROTOCOL_CHANGE` | The concurrent operation upgraded the table protocol (e.g., Delta table reader/writer version). | Retry the operation. |
| `ROW_LEVEL_CHANGES` | The concurrent operation deleted rows that the transaction attempted to read. | Retry the operation. |
| `WHOLE_TABLE_READ` | The transaction attempted to read the entire table, conflicting with concurrent deletion. | Add filters to narrow the data scope and retry. |
| `WHOLE_TABLE_REPLACE` | The concurrent operation replaced all data in the table. | Retry the operation. |
| `WITHOUT_HINT` | The concurrent operation deleted data that was read by this operation (no hint provided). | Retry the operation. |
| `WITH_PARTITION_HINT` | The concurrent operation deleted data in a specific partition that was read. | Retry the operation. |

^[delta_concurrent_delete_read-error-condition-databricks-on-aws.md]

## How to Troubleshoot

1. **Retry the operation.** Most sub‑errors are transient and can be resolved by simply retrying the transaction. Row‑level conflict detection attempts automatic resolution; if that fails, the sub‑error indicates that a retry is appropriate. ^[delta_concurrent_delete_read-error-condition-databricks-on-aws.md]

2. **Add query filters.** For sub‑errors `EMPTY_READ_PREDICATES` and `WHOLE_TABLE_READ`, modify the read query to include specific filters so that only a subset of data is read, reducing the chance of conflict with concurrent deletions. ^[delta_concurrent_delete_read-error-condition-databricks-on-aws.md]

3. **Resolve naming conflicts.** If you see `CHANGE_TYPE_COLUMN`, rename the `_change_type` column in the table, or disable [Change Data Feed](/concepts/delta-change-data-feed-cdf.md) (CDC) on that table to free the reserved metadata column name. ^[delta_concurrent_delete_read-error-condition-databricks-on-aws.md]

4. **Review partitioning and protocol.** For `PROTOCOL_CHANGE` or `PARTITIONED_TABLE_WITHOUT_MERGE_SOURCE`, ensure that the table is using a compatible Delta protocol and that partitioning is correctly configured for row‑level conflict detection. ^[delta_concurrent_delete_read-error-condition-databricks-on-aws.md]

## Related Concepts

- [Delta Lake](/concepts/delta-lake.md) – The storage layer that enforces transaction isolation.
- [Optimistic Concurrency Control](/concepts/delta-lake-optimistic-concurrency-control.md) – The mechanism that detects and raises this conflict error.
- [Change Data Feed](/concepts/delta-change-data-feed-cdf.md) – A feature that can conflict when the table contains a column named `_change_type`.
- [Row‑Level Conflict Resolution](/concepts/row-level-conflict-resolution.md) – Delta Lake's ability to resolve concurrent writes at the row level; if this times out, `ALLOTTED_TIME_EXCEEDED` is returned.

## 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)
