Add BigQuery relation naming macros for concurrent execution

Implements BigQuery-specific relation naming macros to enable concurrent dbt execution without relation name collisions, matching functionality available in PostgreSQL adapter.

Added macros:
  - bigquery__make_relation_with_suffix: Core macro with truncation and datetime
  - bigquery__make_temp_relation: Temp relations with unique datetime suffixes
  - bigquery__make_intermediate_relation: Intermediate relations without datetime
  - bigquery__make_backup_relation: Backup relations with configurable types

Author: RRap0so

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

@@ -213,8 +213,8 @@ having count(*) > 1
 {% macro bigquery__make_relation_with_suffix(base_relation, suffix, dstring) %}
     {% if dstring %}
       {% set dt = modules.datetime.datetime.now() %}
-      {% set dtstring = dt.strftime("%j%H%M%S") %}
-      {% set suffix = suffix ~ "_" ~ dtstring %}
+      {% 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 #}

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