如何使用 generate_series 和 random 为 Postgresql 生成大数据样本？
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How can I generate big data sample for Postgresql using generate_series and random?
提问by abelard2008
I want to generate big data sample (almost 1 million records) for studying tuplesort.c's polyphase merge in postgresql, and I hope the schema as follows:
我想生成大数据样本（近100万条记录）用于研究tuplesort.c在postgresql中的多相合并，希望schema如下：
CREATE TABLE Departments (code VARCHAR(4), UNIQUE (code));
CREATE TABLE Towns (
id SERIAL UNIQUE NOT NULL,
code VARCHAR(10) NOT NULL, -- not unique
article TEXT,
name TEXT NOT NULL, -- not unique
department VARCHAR(4) NOT NULL REFERENCES Departments (code),
UNIQUE (code, department)
);
how to use generate_series and random for do it? thanks a lot!
如何使用 generate_series 和 random 来做呢？多谢！
回答by Clodoaldo Neto
To insert one million rows into Towns
将一百万行插入到 Towns
insert into towns (
code, article, name, department
)
select
left(md5(i::text), 10),
md5(random()::text),
md5(random()::text),
left(md5(random()::text), 4)
from generate_series(1, 1000000) s(i)
Since idis a serialit is not necessary to include it.
由于id是 a serial，因此没有必要包含它。
