Update BigQuery temp relation naming to use microsecond precision

Changes the datetime format from %j%H%M%S (9 digits) to %H%M%S%f (12 digits)
to provide microsecond-level uniqueness for temp table names during concurrent
dbt execution, matching PostgreSQL adapter implementation.

- Update bigquery__make_relation_with_suffix to use %H%M%S%f format
- Add functional tests for BigQuery and PostgreSQL to verify 12-digit format

Author: RRap0so

dbt-bigquery/src/dbt/include/bigquery/macros/adapters.sql

@@ -209,3 +209,34 @@ having count(*) > 1
   {% do adapter.upload_file(local_file_path, database, table_schema, table_name, kwargs=kwargs) %}
 
 {% endmacro %}
+
+{% macro bigquery__make_relation_with_suffix(base_relation, suffix, dstring) %}
+    {% if dstring %}
+      {% set dt = modules.datetime.datetime.now() %}
+      {% set dtstring = dt.strftime("%H%M%S%f") %}
+      {% set suffix = suffix ~ dtstring %}
+    {% endif %}
+    {% set suffix_length = suffix|length %}
+    {% set relation_max_name_length = 1024 %}  {# BigQuery limit #}
+    {% if suffix_length > relation_max_name_length %}
+        {% do exceptions.raise_compiler_error('Relation suffix is too long (' ~ suffix_length ~ ' characters). Maximum length is ' ~ relation_max_name_length ~ ' characters.') %}
+    {% endif %}
+    {% set identifier = base_relation.identifier[:relation_max_name_length - suffix_length] ~ suffix %}
+
+    {{ return(base_relation.incorporate(path={"identifier": identifier })) }}
+
+{% endmacro %}
+
+{% macro bigquery__make_temp_relation(base_relation, suffix) %}
+    {% set temp_relation = bigquery__make_relation_with_suffix(base_relation, suffix, dstring=True) %}
+    {{ return(temp_relation) }}
+{% endmacro %}
+
+{% macro bigquery__make_intermediate_relation(base_relation, suffix) %}
+    {{ return(bigquery__make_relation_with_suffix(base_relation, suffix, dstring=False)) }}
+{% endmacro %}
+
+{% macro bigquery__make_backup_relation(base_relation, backup_relation_type, suffix) %}
+    {% set backup_relation = bigquery__make_relation_with_suffix(base_relation, suffix, dstring=False) %}
+    {{ return(backup_relation.incorporate(type=backup_relation_type)) }}
+{% endmacro %}

dbt-bigquery/tests/functional/adapter/test_temp_relation_naming.py

@@ -0,0 +1,54 @@
+import pytest
+import re
+from pathlib import Path
+from dbt.tests.util import run_dbt
+
+
+_MODEL_INCREMENTAL = """
+{{
+    config(
+        materialized='incremental',
+        unique_key='id',
+        on_schema_change='append_new_columns'
+    )
+}}
+
+select
+    1 as id,
+    'value' as name
+"""
+
+
+class TestTempRelationNaming:
+    @pytest.fixture(scope="class")
+    def models(self):
+        return {"my_incremental_model.sql": _MODEL_INCREMENTAL}
+
+    def test_incremental_with_schema_change_creates_temp_relation(self, project):
+        results = run_dbt(["run"])
+        assert len(results) == 1
+
+        results = run_dbt(["run", "--log-level", "debug", "--log-format", "text"])
+        assert len(results) == 1
+
+        log_dir = Path(project.project_root) / "logs"
+        if log_dir.exists():
+            log_files = sorted(
+                log_dir.glob("dbt.log*"), key=lambda p: p.stat().st_mtime, reverse=True
+            )
+            if log_files:
+                log_content = log_files[0].read_text()
+                temp_table_pattern = r"__dbt_tmp\d{12}\b"
+                matches = re.findall(temp_table_pattern, log_content)
+
+                assert len(matches) > 0, (
+                    f"Expected temp table with pattern '{temp_table_pattern}' "
+                    f"(12 digits from %H%M%S%f format, not old 9-digit %j%H%M%S format)"
+                )
+
+                for match in matches:
+                    suffix = match.replace("__dbt_tmp", "")
+                    assert len(suffix) == 12 and suffix.isdigit()
+
+        results = run_dbt(["run"])
+        assert len(results) == 1

dbt-postgres/tests/functional/adapter/test_temp_relation_naming.py

@@ -0,0 +1,54 @@
+import pytest
+import re
+from pathlib import Path
+from dbt.tests.util import run_dbt
+
+
+_MODEL_INCREMENTAL = """
+{{
+    config(
+        materialized='incremental',
+        unique_key='id',
+        on_schema_change='append_new_columns'
+    )
+}}
+
+select
+    1 as id,
+    'value' as name
+"""
+
+
+class TestTempRelationNaming:
+    @pytest.fixture(scope="class")
+    def models(self):
+        return {"my_incremental_model.sql": _MODEL_INCREMENTAL}
+
+    def test_incremental_with_schema_change_creates_temp_relation(self, project):
+        results = run_dbt(["run"])
+        assert len(results) == 1
+
+        results = run_dbt(["run", "--log-level", "debug", "--log-format", "text"])
+        assert len(results) == 1
+
+        log_dir = Path(project.project_root) / "logs"
+        if log_dir.exists():
+            log_files = sorted(
+                log_dir.glob("dbt.log*"), key=lambda p: p.stat().st_mtime, reverse=True
+            )
+            if log_files:
+                log_content = log_files[0].read_text()
+                temp_table_pattern = r"__dbt_tmp\d{12}\b"
+                matches = re.findall(temp_table_pattern, log_content)
+
+                assert len(matches) > 0, (
+                    f"Expected temp table with pattern '{temp_table_pattern}' "
+                    f"(12 digits from %H%M%S%f format)"
+                )
+
+                for match in matches:
+                    suffix = match.replace("__dbt_tmp", "")
+                    assert len(suffix) == 12 and suffix.isdigit()
+
+        results = run_dbt(["run"])
+        assert len(results) == 1