-- 多广场实例（channel）+ 分类筛选（category）。旧帖默认 channel=square、category 空。

ALTER TABLE t_square_posts
    ADD COLUMN channel VARCHAR(32) NOT NULL DEFAULT 'square' COMMENT '广场实例：square/squarenovel/squaresteps/squarehealth' AFTER user_id,
    ADD COLUMN category VARCHAR(32) NOT NULL DEFAULT '' COMMENT '内容标签：funny/beauty 等；空为未分类' AFTER channel;

ALTER TABLE t_square_posts
    ADD KEY idx_channel_public_feed (channel, audit_status, visibility, id),
    ADD KEY idx_channel_hot (channel, audit_status, visibility, like_count, id),
    ADD KEY idx_channel_category (channel, category, id),
    ADD KEY idx_channel_user (channel, user_id, id);

ALTER TABLE t_square_notices
    ADD COLUMN channel VARCHAR(32) NOT NULL DEFAULT 'square' COMMENT '广场实例，与帖一致' AFTER to_user_id;

ALTER TABLE t_square_notices
    ADD KEY idx_channel_to_user (channel, to_user_id, id);

ALTER TABLE t_square_notice_state
    ADD COLUMN channel VARCHAR(32) NOT NULL DEFAULT 'square' COMMENT '广场实例' AFTER user_id;

ALTER TABLE t_square_notice_state
    DROP PRIMARY KEY,
    ADD PRIMARY KEY (user_id, channel);