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backend/alembic/versions/3bd4c84fe72f_improved_index.py

@@ -6,7 +6,8 @@ Create Date: 2025-02-26 13:07:56.217791
 
 """
 from alembic import op
-
+import time
+from sqlalchemy import text
 
 # revision identifiers, used by Alembic.
 revision = "3bd4c84fe72f"
@@ -27,46 +28,358 @@ depends_on = None
 # 4. Adds indexes to both chat_message and chat_session tables for comprehensive search
 
 
-def upgrade() -> None:
+def upgrade():
-    # Create a GIN index for full-text search on chat_message.message
+    # --- PART 1: chat_message table ---
+    # Step 1: Add nullable column (quick, minimal locking)
+    # op.execute("ALTER TABLE chat_message DROP COLUMN IF EXISTS message_tsv")
+    # op.execute("DROP TRIGGER IF EXISTS chat_message_tsv_trigger ON chat_message")
+    # op.execute("DROP FUNCTION IF EXISTS update_chat_message_tsv()")
+    # op.execute("ALTER TABLE chat_message DROP COLUMN IF EXISTS message_tsv")
+    # # Drop chat_session tsv trigger if it exists
+    # op.execute("DROP TRIGGER IF EXISTS chat_session_tsv_trigger ON chat_session")
+    # op.execute("DROP FUNCTION IF EXISTS update_chat_session_tsv()")
+    # op.execute("ALTER TABLE chat_session DROP COLUMN IF EXISTS title_tsv")
+    # raise Exception("Stop here")
+    time.time()
+    op.execute("ALTER TABLE chat_message ADD COLUMN IF NOT EXISTS message_tsv tsvector")
+
+    # Step 2: Create function and trigger for new/updated rows
     op.execute(
         """
+    CREATE OR REPLACE FUNCTION update_chat_message_tsv()
+    RETURNS TRIGGER AS $$
+    BEGIN
+      NEW.message_tsv = to_tsvector('english', NEW.message);
+      RETURN NEW;
+    END;
+    $$ LANGUAGE plpgsql
+    """
+    )
+
+    # Create trigger in a separate execute call
+    op.execute(
+        """
+    CREATE TRIGGER chat_message_tsv_trigger
+    BEFORE INSERT OR UPDATE ON chat_message
+    FOR EACH ROW EXECUTE FUNCTION update_chat_message_tsv()
+    """
+    )
+
+    # Step 3: Update existing rows in batches using Python
+    time.time()
+
+    # Get connection and count total rows
+    connection = op.get_bind()
+    total_count_result = connection.execute(
+        text("SELECT COUNT(*) FROM chat_message")
+    ).scalar()
+    total_count = total_count_result if total_count_result is not None else 0
+    batch_size = 5000
+    batches = 0
+
+    # Calculate total batches needed
+    total_batches = (
+        (total_count + batch_size - 1) // batch_size if total_count > 0 else 0
+    )
+
+    # Process in batches - properly handling UUIDs by using OFFSET/LIMIT approach
+    for batch_num in range(total_batches):
+        offset = batch_num * batch_size
+
+        # Execute update for this batch using OFFSET/LIMIT which works with UUIDs
+        connection.execute(
+            text(
+                """
+            UPDATE chat_message
+            SET message_tsv = to_tsvector('english', message)
+            WHERE id IN (
+                SELECT id FROM chat_message
+                WHERE message_tsv IS NULL
+                ORDER BY id
+                LIMIT :batch_size OFFSET :offset
+            )
+            """
+            ).bindparams(batch_size=batch_size, offset=offset)
+        )
+
+        # Commit each batch
+        connection.execute(text("COMMIT"))
+        # Start a new transaction
+        connection.execute(text("BEGIN"))
+
+        batches += 1
+
+    # Final check for any remaining NULL values
+    connection.execute(
+        text(
+            """
+    UPDATE chat_message SET message_tsv = to_tsvector('english', message)
+    WHERE message_tsv IS NULL
+    """
+        )
+    )
+
+    # Create GIN index concurrently
+    connection.execute(text("COMMIT"))
+
+    time.time()
+
+    connection.execute(
+        text(
+            """
+    CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_chat_message_tsv
+    ON chat_message USING GIN (message_tsv)
+    """
+        )
+    )
+
+    # First drop the trigger as it won't be needed anymore
+    connection.execute(
+        text(
+            """
+    DROP TRIGGER IF EXISTS chat_message_tsv_trigger ON chat_message;
+    """
+        )
+    )
+
+    connection.execute(
+        text(
+            """
+    DROP FUNCTION IF EXISTS update_chat_message_tsv();
+    """
+        )
+    )
+
+    # Add new generated column
+    time.time()
+    connection.execute(
+        text(
+            """
     ALTER TABLE chat_message
-        ADD COLUMN message_tsv tsvector
+    ADD COLUMN message_tsv_gen tsvector
     GENERATED ALWAYS AS (to_tsvector('english', message)) STORED;
     """
         )
-
-    # Commit the current transaction before creating concurrent indexes
-    op.execute("COMMIT")
-
-    op.execute(
-        """
-        CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_chat_message_tsv
-        ON chat_message
-        USING GIN (message_tsv)
-        """
     )
 
-    # Also add a stored tsvector column for chat_session.description
+    connection.execute(text("COMMIT"))
-    op.execute(
+
+    time.time()
+
+    connection.execute(
+        text(
             """
-        ALTER TABLE chat_session
+    CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_chat_message_tsv_gen
-        ADD COLUMN description_tsv tsvector
+    ON chat_message USING GIN (message_tsv_gen)
-        GENERATED ALWAYS AS (to_tsvector('english', coalesce(description, ''))) STORED;
     """
         )
+    )
 
-    # Commit again before creating the second concurrent index
+    # Drop old index and column
-    op.execute("COMMIT")
+    connection.execute(text("COMMIT"))
 
-    op.execute(
+    connection.execute(
+        text(
+            """
+    DROP INDEX CONCURRENTLY IF EXISTS idx_chat_message_tsv;
+    """
+        )
+    )
+    connection.execute(text("COMMIT"))
+    connection.execute(
+        text(
+            """
+    ALTER TABLE chat_message DROP COLUMN message_tsv;
+    """
+        )
+    )
+
+    # Rename new column to old name
+    connection.execute(
+        text(
+            """
+    ALTER TABLE chat_message RENAME COLUMN message_tsv_gen TO message_tsv;
+    """
+        )
+    )
+
+    # --- PART 2: chat_session table ---
+
+    # Step 1: Add nullable column (quick, minimal locking)
+    time.time()
+    connection.execute(
+        text(
+            "ALTER TABLE chat_session ADD COLUMN IF NOT EXISTS description_tsv tsvector"
+        )
+    )
+
+    # Step 2: Create function and trigger for new/updated rows - SPLIT INTO SEPARATE CALLS
+    connection.execute(
+        text(
+            """
+    CREATE OR REPLACE FUNCTION update_chat_session_tsv()
+    RETURNS TRIGGER AS $$
+    BEGIN
+      NEW.description_tsv = to_tsvector('english', COALESCE(NEW.description, ''));
+      RETURN NEW;
+    END;
+    $$ LANGUAGE plpgsql
+    """
+        )
+    )
+
+    # Create trigger in a separate execute call
+    connection.execute(
+        text(
+            """
+    CREATE TRIGGER chat_session_tsv_trigger
+    BEFORE INSERT OR UPDATE ON chat_session
+    FOR EACH ROW EXECUTE FUNCTION update_chat_session_tsv()
+    """
+        )
+    )
+
+    # Step 3: Update existing rows in batches using Python
+    time.time()
+
+    # Get the maximum ID to determine batch count
+    # Cast id to text for MAX function since it's a UUID
+    max_id_result = connection.execute(
+        text("SELECT COALESCE(MAX(id::text), '0') FROM chat_session")
+    ).scalar()
+    max_id_result if max_id_result is not None else "0"
+    batch_size = 5000
+    batches = 0
+
+    # Get all IDs ordered to process in batches
+    rows = connection.execute(
+        text("SELECT id FROM chat_session ORDER BY id")
+    ).fetchall()
+    total_rows = len(rows)
+
+    # Process in batches
+    for batch_num, batch_start in enumerate(range(0, total_rows, batch_size)):
+        batch_end = min(batch_start + batch_size, total_rows)
+        batch_ids = [row[0] for row in rows[batch_start:batch_end]]
+
+        if not batch_ids:
+            continue
+
+        # Use IN clause instead of BETWEEN for UUIDs
+        placeholders = ", ".join([f":id{i}" for i in range(len(batch_ids))])
+        params = {f"id{i}": id_val for i, id_val in enumerate(batch_ids)}
+
+        # Execute update for this batch
+        connection.execute(
+            text(
+                f"""
+            UPDATE chat_session
+            SET description_tsv = to_tsvector('english', COALESCE(description, ''))
+            WHERE id IN ({placeholders})
+            AND description_tsv IS NULL
+            """
+            ).bindparams(**params)
+        )
+
+        # Commit each batch
+        connection.execute(text("COMMIT"))
+        # Start a new transaction
+        connection.execute(text("BEGIN"))
+
+        batches += 1
+
+    # Final check for any remaining NULL values
+    connection.execute(
+        text(
+            """
+    UPDATE chat_session SET description_tsv = to_tsvector('english', COALESCE(description, ''))
+    WHERE description_tsv IS NULL
+    """
+        )
+    )
+
+    # Create GIN index concurrently
+    connection.execute(text("COMMIT"))
+
+    time.time()
+    connection.execute(
+        text(
             """
     CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_chat_session_desc_tsv
-        ON chat_session
+    ON chat_session USING GIN (description_tsv)
-        USING GIN (description_tsv)
     """
         )
+    )
+
+    # After Final check for chat_session
+    # First drop the trigger as it won't be needed anymore
+    connection.execute(
+        text(
+            """
+    DROP TRIGGER IF EXISTS chat_session_tsv_trigger ON chat_session;
+    """
+        )
+    )
+
+    connection.execute(
+        text(
+            """
+    DROP FUNCTION IF EXISTS update_chat_session_tsv();
+    """
+        )
+    )
+    # Add new generated column
+    time.time()
+    connection.execute(
+        text(
+            """
+    ALTER TABLE chat_session
+    ADD COLUMN description_tsv_gen tsvector
+    GENERATED ALWAYS AS (to_tsvector('english', COALESCE(description, ''))) STORED;
+    """
+        )
+    )
+
+    # Create new index on generated column
+    connection.execute(text("COMMIT"))
+
+    time.time()
+    connection.execute(
+        text(
+            """
+    CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_chat_session_desc_tsv_gen
+    ON chat_session USING GIN (description_tsv_gen)
+    """
+        )
+    )
+
+    # Drop old index and column
+    connection.execute(text("COMMIT"))
+
+    connection.execute(
+        text(
+            """
+    DROP INDEX CONCURRENTLY IF EXISTS idx_chat_session_desc_tsv;
+    """
+        )
+    )
+    connection.execute(text("COMMIT"))
+    connection.execute(
+        text(
+            """
+    ALTER TABLE chat_session DROP COLUMN description_tsv;
+    """
+        )
+    )
+
+    # Rename new column to old name
+    connection.execute(
+        text(
+            """
+    ALTER TABLE chat_session RENAME COLUMN description_tsv_gen TO description_tsv;
+    """
+        )
+    )
 
 
 def downgrade() -> None: