Postgres日期重叠约束

Question

我有这样一张桌子:

date_start    date_end     account_id    product_id
2001-01-01    2001-01-31   1             1
2001-02-01    2001-02-20   1             1
2001-04-01    2001-05-20   1             1

我想禁止给定的重叠间隔 (account_id, product_id)

编辑:我找到了一些东西:

CREATE TABLE test (                                                                                                
    from_ts TIMESTAMPTZ,
    to_ts TIMESTAMPTZ,
    account_id INTEGER,
    product_id INTEGER,
    CHECK ( from_ts < to_ts ),
    CONSTRAINT overlapping_times EXCLUDE USING GIST (
        account_id WITH =,
        product_id WITH =,
        box(
            point( extract(epoch FROM from_ts at time zone 'UTC'), extract(epoch FROM from_ts at time zone 'UTC') ),
            point( extract(epoch FROM to_ts at time zone 'UTC') , extract(epoch FROM to_ts at time zone 'UTC') )
        ) WITH &&
    )
);

如果您想了解更多有关此内容的信息,请访问http://www.depesz.com/2010/01/03/waiting-for-8-5-exclusion-constraints/

我唯一的问题是它不能使用空值作为结束时间戳,我想用无限值替换它但不起作用.

Answer 1

好的,我最终做到了这一点:

CREATE TABLE test (
    from_ts TIMESTAMPTZ,
    to_ts TIMESTAMPTZ,
    account_id INTEGER DEFAULT 1,
    product_id INTEGER DEFAULT 1,
    CHECK ( from_ts < to_ts ),
    CONSTRAINT overlapping_times EXCLUDE USING GIST (
        account_id WITH =,
        product_id WITH =,
        period(from_ts, CASE WHEN to_ts IS NULL THEN 'infinity' ELSE to_ts END) WITH &&
    )
);

与无限,交易证明完美配合.

我只需安装时间扩展,这将在postgres 9.2中生成,btree_gist可作为9.1中的扩展. CREATE EXTENSION btree_gist;

nb:如果你没有空时间戳,就不需要使用时间扩展,你可以使用我的问题中指定的box方法.

Answer 2

在最新的 postgres 版本中（我在 9.6 中对其进行了测试，但我认为它可以在 >=9.2 中工作）您可以使用tstzrange()其他一些评论中提到的内置函数。默认情况下，空值将被视为正无穷大或负无穷大，然后不再明确需要 CHECK 约束（如果您认为检查只是<=一个范围可以以相同日期开始和结束）。只btree_gist需要扩展名：

CREATE EXTENSION btree_gist;

CREATE TABLE test (
    from_ts TIMESTAMPTZ,
    to_ts TIMESTAMPTZ,
    account_id INTEGER DEFAULT 1,
    product_id INTEGER DEFAULT 1,
    CONSTRAINT overlapping_times EXCLUDE USING GIST (
        account_id WITH =,
        product_id WITH =,
        TSTZRANGE(from_ts, to_ts) WITH &&
    )
);