fix: enforce 255-character identifier length limit for Databricks relations by psaikaushik · Pull Request #1391 · databricks/dbt-databricks

psaikaushik · 2026-04-12T22:59:18Z

Summary

Enforces the 255-character identifier length limit for Databricks relations at relation creation time, preventing a cryptic runtime DatabricksExecutionError when store_failures generates overly-long table names.

Closes #1309

Problem

When store_failures: true is enabled, dbt generates table names by concatenating the test name, model name, and arguments. For deep schema tests with verbose names, this can exceed Databricks' 255-character limit for table names, causing:

[RequestId=...] Invalid input: RPC CreateStagingTable Field
managedcatalog.StagingTableInfo.name: name "accepted_map_keys_stg_product_search_create_sizes__relax__..." too long.
Maximum length is 255 characters.

This error is unhelpful — it doesn't explain what the 255-character limit is, which test/model caused it, or how to fix it.

Fix

Added relation_max_name_length() and __post_init__ validation to DatabricksRelation, following the exact same pattern used by the Postgres adapter:

MAX_CHARACTERS_IN_IDENTIFIER = 255

def relation_max_name_length(self):
    return MAX_CHARACTERS_IN_IDENTIFIER

def __post_init__(self):
    if (
        self.identifier is not None
        and self.type is not None
        and len(self.identifier) > self.relation_max_name_length()
    ):
        raise DbtRuntimeError(
            f"Relation name '{self.identifier}' "
            f"is longer than {self.relation_max_name_length()} characters. ..."
        )

Before:

[RequestId=...] Invalid input: RPC CreateStagingTable ... name "accepted_map_keys_stg_..." too long.

After:

Relation name 'accepted_map_keys_stg_product_search_create_sizes__...'
is longer than 255 characters. Databricks has a maximum identifier
length of 255 characters. If this is a store_failures table, consider
using a shorter test name or setting a custom alias.

Checklist

Follows the same pattern as the Postgres adapter
Catches the error at relation creation time, not at SQL execution
Error message includes actionable guidance

sd-db · 2026-04-21T08:17:48Z

HI @psaikaushik can you select Allow edits from maintainers or do a rebase from main. The tests are failing because the branch is in an inconsistent state w.r.t CI and can 't review without it.

sd-db

In addition to the issues raised, let us also add an entry in CHANGELOG.md on the fix. Thanks again for the PR.

psaikaushik · 2026-04-21T21:55:52Z

HI @psaikaushik can you select Allow edits from maintainers or do a rebase from main. The tests are failing because the branch is in an inconsistent state w.r.t CI and can 't review without it.

Just allowed edit for maintainers and also rebased on the main. Thanks @sd-db

…ations Add relation_max_name_length() returning 255 and a __post_init__ validation to DatabricksRelation, following the same pattern used by the Postgres adapter. This catches overly-long table names (commonly generated by store_failures for tests with verbose names) at relation creation time with a clear error message instead of a cryptic runtime DatabricksExecutionError from the SQL engine. Closes databricks#1309

psaikaushik · 2026-04-21T21:57:53Z

@sd-db : Please take a look at the PR now. Addressed all the comments. Thanks!

…ength validation (databricks#1309) Address review feedback: - Remove verbose comment block from MAX_CHARACTERS_IN_IDENTIFIER constant - Remove redundant inline comments from __post_init__ (implied by the code) - Simplify the error message (no repetition of the limit value) - Add TestIdentifierLengthValidation unit tests covering valid length, too-long raises DbtRuntimeError, no-type skips check, None identifier - Add CHANGELOG entry under 1.11.7 https://claude.ai/code/session_017ZAXMwLSnqz4FqvTt5H7D1

sd-db · 2026-04-21T08:24:23Z

+                f"is longer than {self.relation_max_name_length()} characters. "
+                f"Databricks has a maximum identifier length of "
+                f"{self.relation_max_name_length()} characters. "
+                f"If this is a store_failures table, consider using a shorter "


We have hardcoded store_failures here but the validator fires on any oversized identifier (models/seeds/snapshots)

sd-db · 2026-04-22T05:13:00Z



+class TestIdentifierLengthValidation:
+    def test_relation_max_name_length(self):


This test is failing, also we should remove this test as this is not required.

sd-db · 2026-04-22T05:14:00Z

+                    "Use a shorter test name or configure a custom alias."
+                )
+
+    def relation_max_name_length(self):


imo best to make this a classmethod

Also add a return type annotation -> int

sd-db · 2026-04-22T05:14:21Z

 - Fix `workflow_job` Python model submission method failing with dictionary attribute error ([#1360](https://github.com/databricks/dbt-databricks/issues/1360))
 - Fix `TestWorkflowJob` functional test that was unreachable on all profiles due to incorrect skip list, wrong model fixture, and invalid `max_retries` parameter ([#1360](https://github.com/databricks/dbt-databricks/issues/1360))
 - Fix column order mismatch in microbatch and replace_where incremental strategies by using INSERT BY NAME syntax ([#1338](https://github.com/databricks/dbt-databricks/issues/1338))
+- Validate relation identifier length at creation time and raise a clear error when it exceeds Databricks' 255-character limit, preventing confusing runtime failures when `store_failures: true` generates long table names ([#1309](https://github.com/databricks/dbt-databricks/issues/1309))


Move this to 1.11.8

sd-db · 2026-04-22T05:15:59Z

+                raise DbtRuntimeError(
+                    f"Relation name '{self.identifier}' is longer than "
+                    f"{self.relation_max_name_length()} characters. "
+                    "Use a shorter test name or configure a custom alias."


post_init is valid for all relations and not just test. I think a better comment is probably something like - Databricks has a maximum identifier length of 255 characters. Use a shorter name or configure a custom alias.

- Add @classmethod decorator and -> int return type to relation_max_name_length() - Broaden error message to not mention store_failures specifically; the validator fires on any oversized identifier (models, seeds, snapshots, etc.) - Remove test_relation_max_name_length test (failing and not required per review) - Move CHANGELOG entry from 1.11.7 to new 1.11.8 section https://claude.ai/code/session_017ZAXMwLSnqz4FqvTt5H7D1

psaikaushik · 2026-04-22T17:00:06Z

@sd-db : Addressed all the comments. Please take a look. thanks!

Error message called relation_max_name_length() three times and stated the limit redundantly. Align with reviewer's exact suggested wording: "Databricks has a maximum identifier length of N characters. Use a shorter name or configure a custom alias." Update test match pattern accordingly. https://claude.ai/code/session_017ZAXMwLSnqz4FqvTt5H7D1

psaikaushik requested review from benc-db, jprakash-db, sd-db and tejassp-db as code owners April 12, 2026 22:59

sd-db requested changes Apr 21, 2026

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Comment thread dbt/adapters/databricks/relation.py Outdated

Comment thread dbt/adapters/databricks/relation.py Outdated

Comment thread dbt/adapters/databricks/relation.py Outdated

psaikaushik force-pushed the fix/1309-relation-max-name-length branch from 8494a15 to 6688bce Compare April 21, 2026 21:57

psaikaushik requested a review from sd-db April 21, 2026 21:58

psaikaushik force-pushed the fix/1309-relation-max-name-length branch from 0c3add9 to 2e759c2 Compare April 21, 2026 22:14

psaikaushik force-pushed the fix/1309-relation-max-name-length branch from 2e759c2 to a8b866b Compare April 21, 2026 22:17

sd-db self-assigned this Apr 22, 2026

sd-db reviewed Apr 22, 2026

View reviewed changes

psaikaushik force-pushed the fix/1309-relation-max-name-length branch from 87ebdcf to 75a59a3 Compare April 22, 2026 16:57

psaikaushik requested a review from sd-db April 22, 2026 17:06

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fix: enforce 255-character identifier length limit for Databricks relations#1391

fix: enforce 255-character identifier length limit for Databricks relations#1391
psaikaushik wants to merge 4 commits intodatabricks:mainfrom
psaikaushik:fix/1309-relation-max-name-length

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		class TestIdentifierLengthValidation:
		def test_relation_max_name_length(self):

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psaikaushik commented Apr 12, 2026

Summary

Problem

Fix

Checklist

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