fix: use py_<YYMMDD_HHMMSS>_<branch>_<hash> schema naming to prevent CI collisions (#2126)

* fix: use py_<yymmdd>_<branch>_<hash> schema naming to prevent CI collisions

Replace the old truncation-based schema naming with a hash-based approach
that prevents cross-branch collisions when concurrent CI jobs share the
same warehouse. Uses py_ prefix to identify the Python package CI
(matching dbt_ prefix in dbt-data-reliability).

Format: py_<YYMMDD>_<branch≤29>_<8-char-hash>
The hash is derived from the concurrency group key.

Co-Authored-By: Itamar Hartstein <haritamar@gmail.com>

* style: collapse consecutive underscores in SAFE_BRANCH (CodeRabbit nitpick)

Co-Authored-By: Itamar Hartstein <haritamar@gmail.com>

* feat: add HHMM to schema timestamp for per-run uniqueness

Co-Authored-By: Itamar Hartstein <haritamar@gmail.com>

* style: use explicit UTC for timestamp (date -u)

Co-Authored-By: Itamar Hartstein <haritamar@gmail.com>

* style: add seconds to timestamp (YYMMDD_HHMMSS) per maintainer request

Co-Authored-By: Itamar Hartstein <haritamar@gmail.com>

---------

Co-authored-by: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>
Co-authored-by: Itamar Hartstein <haritamar@gmail.com>

Author: devin-ai-integration[bot]

.github/workflows/test-warehouse.yml

@@ -65,7 +65,8 @@ jobs:
       run:
         working-directory: elementary
     concurrency:
-      # This is what eventually defines the schema name in the data platform.
+      # Serialises runs for the same warehouse × dbt-version × branch.
+      # The schema name is derived from a hash of this group (see "Write dbt profiles").
       group: tests_${{ inputs.warehouse-type }}_dbt_${{ inputs.dbt-version }}_${{ github.head_ref || github.ref_name }}
       cancel-in-progress: true
     steps:
@@ -116,13 +117,26 @@ jobs:
         env:
           CI_WAREHOUSE_SECRETS: ${{ secrets.CI_WAREHOUSE_SECRETS || '' }}
         run: |
-          DBT_VERSION=$(pip show dbt-core | grep -i version | awk '{print $2}' | sed 's/\.//g')
-          UNDERSCORED_REF_NAME=$(echo "${{ inputs.warehouse-type }}_dbt_${DBT_VERSION}_${BRANCH_NAME}" | awk '{print tolower($0)}' | head -c 40 | sed "s/[-\/]/_/g")
+          # Schema name = py_<YYMMDD_HHMMSS>_<branch≤19>_<8-char hash>
+          # The hash prevents collisions across concurrent jobs; the branch
+          # keeps it human-readable; the timestamp helps with stale schema
+          # cleanup and ensures each CI run gets a unique schema.
+          #
+          # Budget (PostgreSQL 63-char limit):
+          #   py_(3) + timestamp(13) + _(1) + branch(≤19) + _(1) + hash(8) = 45
+          #   + _elementary(11) + _gw7(4) = 60
+          CONCURRENCY_GROUP="tests_${{ inputs.warehouse-type }}_dbt_${{ inputs.dbt-version }}_${BRANCH_NAME}"
+          SHORT_HASH=$(echo -n "$CONCURRENCY_GROUP" | sha256sum | head -c 8)
+          SAFE_BRANCH=$(echo "${BRANCH_NAME}" | awk '{print tolower($0)}' | sed "s/[^a-z0-9]/_/g; s/__*/_/g" | head -c 19)
+          DATE_STAMP=$(date -u +%y%m%d_%H%M%S)
+          SCHEMA_NAME="py_${DATE_STAMP}_${SAFE_BRANCH}_${SHORT_HASH}"
+
+          echo "Schema name: $SCHEMA_NAME (branch='${BRANCH_NAME}', timestamp=${DATE_STAMP}, hash of concurrency group)"
 
           python "${{ github.workspace }}/elementary/tests/profiles/generate_profiles.py" \
             --template "${{ github.workspace }}/elementary/tests/profiles/profiles.yml.j2" \
             --output ~/.dbt/profiles.yml \
-            --schema-name "py_$UNDERSCORED_REF_NAME"
+            --schema-name "$SCHEMA_NAME"
 
       - name: Run Python package unit tests
         run: pytest -vv tests/unit --warehouse-type ${{ inputs.warehouse-type }}