-- 客户列表按当前页 external_userid 批量读取加客渠道流水。
-- 覆盖 change_type + external_userid + event_time，避免事件量增长后反复扫描全量 add 事件。
SET @idx_change_ext_time_exists := (
    SELECT COUNT(*)
    FROM information_schema.STATISTICS
    WHERE TABLE_SCHEMA = DATABASE()
      AND TABLE_NAME = 'zyt_qywx_external_contact_event'
      AND INDEX_NAME = 'idx_change_ext_time'
);

SET @add_idx_change_ext_time_sql := IF(
    @idx_change_ext_time_exists = 0,
    'ALTER TABLE `zyt_qywx_external_contact_event` ADD INDEX `idx_change_ext_time` (`change_type`, `external_userid`, `event_time`, `id`)',
    'SELECT 1'
);

PREPARE add_idx_change_ext_time_stmt FROM @add_idx_change_ext_time_sql;
EXECUTE add_idx_change_ext_time_stmt;
DEALLOCATE PREPARE add_idx_change_ext_time_stmt;