add indexes for complex queries

Author: zcesur

priv/repo/migrations/20251009162323_add_talent_query_performance_indexes.exs

@@ -0,0 +1,37 @@
+defmodule Algora.Repo.Migrations.AddTalentQueryPerformanceIndexes do
+  use Ecto.Migration
+
+  @disable_ddl_transaction true
+  @disable_migration_lock true
+
+  def change do
+    # Index 1: Composite index for job_postings subquery (org-specific job exclusion)
+    # Improves: SELECT id FROM job_postings WHERE user_id IN (...)
+    create_if_not_exists index(:job_postings, [:user_id, :id], concurrently: true)
+
+    # Index 2: Composite index for job_interviews lookup (org-specific interview exclusion)
+    # Improves: WHERE ji.user_id = ? AND ji.status != 'initial' AND ji.job_posting_id IN (...)
+    create_if_not_exists index(:job_interviews, [:user_id, :status, :job_posting_id], concurrently: true)
+
+    # Index 3: Composite index for users handle lookup in subquery
+    # Improves: SELECT id FROM users WHERE handle = ?
+    create_if_not_exists index(:users, [:handle, :id],
+      where: "handle IS NOT NULL",
+      concurrently: true
+    )
+
+    # Index 4: Composite index for main pipeline filter combination
+    # Improves the base WHERE clause filters applied to all talent queries
+    create_if_not_exists index(
+      :users,
+      [:type, :open_to_new_role, :country, :provider_login],
+      where: "type = 'individual' AND open_to_new_role = true AND provider_login IS NOT NULL",
+      concurrently: true,
+      name: :users_pipeline_base_idx
+    )
+
+    # Index 5: Index for job_matches user_id lookup
+    # Improves: WHERE jm.user_id = ? AND jm.job_posting_id IN (...)
+    create_if_not_exists index(:job_matches, [:user_id, :job_posting_id], concurrently: true)
+  end
+end