added votes index and documented future migration tasks

migrations/002_add_votes_index.sql

@@ -0,0 +1,48 @@
+-- =====================================================================
+-- WebGIS Citizen Participation Portal
+-- Migration: 002_add_votes_index.sql
+-- Description: Adds missing Index on votes.contribution_id for fast
+--              Vote Lookups per Contribution.
+-- =====================================================================
+
+
+-- ---------------------------------------------------------------------
+-- Block 1: Index for fast Queries
+-- The UNIQUE Constraint on contribution_id and voter_name creates a
+-- composite Index, but Queries filtering only by contribution_id
+-- cannot use it efficiently. This single-column Index covers that Case.
+-- ---------------------------------------------------------------------
+CREATE INDEX votes_contribution_idx ON votes (contribution_id);
+
+
+-- =====================================================================
+-- ToDo's for future Migrations
+-- =====================================================================
+--
+-- 1. Categories Table
+--    Create a "categories" Table with municipality_id, slug, label,
+--    icon (FontAwesome), color, and sort_order. Replace the free-text
+--    "category" Column in Contributions with a Foreign Key Reference.
+--    This prevents Typos and inconsistent Category Names, and allows
+--    each Municipality to define its own Set of Categories.
+--
+-- 2. Soft Delete
+--    Add "deleted_at TIMESTAMPTZ DEFAULT NULL" to Contributions.
+--    Instead of DELETE, set deleted_at = NOW(). Filter all Queries
+--    with "WHERE deleted_at IS NULL". Allows Moderation Audit Trail
+--    and accidental Deletion Recovery.
+--
+-- 3. Audit Log
+--    Create an "audit_log" Table recording who changed what and when.
+--    Columns: audit_id, table_name, record_id, action (insert/update/
+--    delete), changed_by, old_values (JSONB), new_values (JSONB),
+--    created_at. Populate via Triggers on Contributions and Votes.
+--
+-- 4. Geometry Validation
+--    Add CHECK Constraint "ST_IsValid(geom)" on Contributions, or
+--    validate in the API Layer before Insert. Prevents self-crossing
+--    Polygons and other invalid Geometries.
+--
+-- =====================================================================
+-- End of migration 002_add_votes_index.sql
+-- =====================================================================