数据结构 YAML 支持的数据结构有三种:对象:键值对的集合,又称为映射(mapping)、散列(...: postgres host: localhost & 用来建立锚点(defaults),换为空格,但保留最后一行的换行符。...>-(缺省行为)当内容换行时,替换为空格,不保留最后一行的换行符。...第一步,将 YAML 配置文件的内容在 Con
postgres 字符串 截取 本节描述了用于检查和操作字符串数值的函数和操作符。在这个环境中的字符串包括所有 character, character varying, text 类型的值。除非另外说明,所有下面列出的函数都可以处理这些类型,不过要小心的是,在使用 character SQL 定义了一些字符串函数,它们有指定的语法(用特定的关键字而不是逗号来...
函数:convert_from(string bytea, src_encoding name) 说明:Convert string to the database encoding. The original encoding is specified by src_encoding. The string must be valid in this encoding. 转换字符串编码,自己要指定源编码,目标编码默认为数据库指定编码, 例子:convert_from('text_in_utf8', '...
Temporal primary, unique and foreign keys (revert: 8aee330a) Planner: remove redundant self-joins (revert: d1d286d8) pg_constraint: NOT NULL constraints (revert: 16f8bb7c1) Now, letʼs get to the new stuff. SQL commands New features of the MERGE command COPY ... FROM: messages ...
Speeded up the serial portion of parallel aggregates and better scales the following in parallel queries: sum(numeric)avg(numeric)var_pop(numeric)variance(numeric)stddev_pop(numericstddev_samp(numeric)stddev(numeric)array_agg(anyarray) string_agg(text)string_agg(bytea) Introduced built-in collation...
例如下面截图 展示的就是我们常用的PG native表达式函数convert_from/bytea/... 的调用代码段。 可以看到734行 调用函数指针 fn_addr(fcinfo), 并返回结果给Datum d,并最终把结果赋值给op->resvalue,完成函数计算由于表达式是一颗树,因此在计算完成后需要进入树的上一层结构中继续计算。 PG 应该没有按照...
pg_convert— 将关联的数组值转换为适合 SQL 语句的格式。 pg_copy_from— 根据数组将记录插入表中 pg_copy_to— 将一个表拷贝到数组中 pg_dbname— 获得数据库名 pg_delete— 删除记录 pg_end_copy— 与 PostgreSQL 后端同步 pg_escape_bytea— 转义 bytea 类型的二进制数据 ...
1.- Convert it to a bytea, in a controlled encoding: convert_to(string text, dest_encoding name) => bytea 2.- Then encode the bytes in hex: encode(data bytea, format text) => text then, to revert it you: 3.- Decode the hex string to bytes: decode(string text, format text)...
Oracle converts names of schema, tables, columns, and functions to uppercase unless the name is given in quotes, while Postgres converts them to lowercase unless given in quotes. You should be safe as long as the application consistently quotes or does not quote the identi...
Once this is complete, you will be able to select Postgres as a source for replicating data.Step 1: Create a dedicated read-only Postgres user These steps create a dedicated read-only user for replicating data. Alternatively, you can use an existing Postgres user in your database. The ...