相关疑难解决方法(0)

查看Postgres 9.4数据类型JSONB的文档,对我来说如何对JSONB列进行更新并不是很明显.

JSONB类型和函数的文档:

http://www.postgresql.org/docs/9.4/static/functions-json.html http://www.postgresql.org/docs/9.4/static/datatype-json.html

作为示例,我有这个基本的表结构:

CREATE TABLE test(id serial, data jsonb);

插入很简单,如:

INSERT INTO test(data) values ('{"name": "my-name", "tags": ["tag1", "tag2"]}');

现在,我将如何更新"数据"列？这是无效的语法:

UPDATE test SET data->'name' = 'my-other-name' WHERE id = 1;

这个文件记录在哪里,我错过了吗？谢谢.

我正在将数据库从MySQL切换到Postgres SQL.在MySQL中工作的选择查询在Postgres中有效,但类似的删除查询却没有.

我有两个数据表,列出了某些备份文件所在的位置.现有数据(ed)和新数据(nd).此语法将挑选出现有数据,这些数据可能表明文件在现有数据表中的位置,将其与相等的文件名和路径进行匹配,但没有关于它在新数据中的位置的信息:

SELECT ed.id, ed.file_name, ed.cd_name, ed.path, nd.cd_name
FROM tv_episodes AS ed
LEFT OUTER JOIN data AS nd ON
ed.file_name = nd.file_name AND 
ed.path = nd.path
WHERE ed.cd_name = 'MediaLibraryDrive' AND nd.cd_name IS NULL;

我希望使用以下语法运行删除查询:

DELETE ed
FROM tv_episodes AS ed
LEFT OUTER JOIN data AS nd ON
ed.file_name = nd.file_name AND 
ed.path = nd.path
WHERE ed.cd_name = 'MediaLibraryDrive' AND nd.cd_name IS NULL;

我试过DELETE ed,DELETE ed.*两者都渲染syntax error at or near "ed".如果我尝试没有别名的类似错误ed.如果我尝试 …

使用PostgreSQL 8.4.9,我对查询的PostgreSQL性能有一个奇怪的问题.此查询正在选择3D卷中的一组点,使用a LEFT OUTER JOIN添加相关ID列,其中存在相关ID.x范围的微小变化可能导致PostgreSQL选择不同的查询计划,执行时间从0.01秒到50秒.这是有问题的查询:

SELECT treenode.id AS id,
       treenode.parent_id AS parentid,
       (treenode.location).x AS x,
       (treenode.location).y AS y,
       (treenode.location).z AS z,
       treenode.confidence AS confidence,
       treenode.user_id AS user_id,
       treenode.radius AS radius,
       ((treenode.location).z - 50) AS z_diff,
       treenode_class_instance.class_instance_id AS skeleton_id
  FROM treenode LEFT OUTER JOIN
         (treenode_class_instance INNER JOIN
          class_instance ON treenode_class_instance.class_instance_id
                                                  = class_instance.id
                            AND class_instance.class_id = 7828307)
       ON (treenode_class_instance.treenode_id = treenode.id
           AND treenode_class_instance.relation_id = 7828321)
  WHERE treenode.project_id = 4
    AND (treenode.location).x >= 8000
    AND (treenode.location).x <= (8000 + 4736) …

我得到了一个大的(> 100M行)Postgres表,其结构为{integer,integer,integer,timestamp without time zone}.我期望一行的大小为3*整数+ 1*时间戳= 3*4 + 1*8 = 20字节.

实际上,行大小pg_relation_size(tbl) / count(*)= 52字节.为什么？

(不对表进行删除:pg_relation_size(tbl, 'fsm')〜= 0)

问题实际上是关于 sql 查询的优化。假设我们有这样定义的表。

CREATE TYPE record_type AS ENUM (
  'TRANSFER',
  'TRADE',
  'VOUCHER'
);

CREATE TYPE record_status AS ENUM (
  'NEW',
  'VALIDATED',
  'EXPIRED'
);

CREATE TABLE good_records (
  id uuid PRIMARY KEY,
  user_id uuid NOT NULL,
  type record_type NOT NULL,
  status record_status NOT NULL,
  amount numeric(36,18) NOT NULL DEFAULT 0,
  expired_at timestamp WITH TIME ZONE NOT NULL,
  notification_sent boolean DEFAULT false,
);

我想每 10 分钟运行一次过期检查，即我会运行SELECT * FROM good_records where record_status = 'NEW' and notification_sent = false（和SELECT * FROM …