dbsetup.sql

利用广度优先遍历搜索一定范围内的所有网页,可用于建立搜索引擎和查找网络错误.

--
--	Script of commands to create crawler database.
--	
--
--
--	Usage: psql -U postgres template1 -f ./dbsetup.sql
--		where postgres is user name, 
--		template1 is dbname, 
--		./dbsetup.sql is file name of the list of commands to be executed.
--
--
--	Note: The following problems were found in PostgreSQL 8.0 for Windows.
--		1. If any statement fails with relation/column names,
--			try to surround them by double quotes or
--			check uppercase/lowercase.
--		2. Do not use upper-case letters in a table name.
--

/* clean up old tables;
   must drop tables with foreign keys first
   due to referential integrity constraints

   "delete from" and "drop table" are for a demonstration purpose only.
   "drop database" will drop them all anyway.
 */
/*
\connect crawler postgres

delete from link;
drop table link;
*/

\connect template1 postgres;


--
--	Drop the database and start from scratch
--	Alternatively, do
--		dropdb crawler
--	at command line:
Drop Database "crawler";



--
-- Selected TOC Entries:
--
--
-- Name: cralwer Type: DATABASE Owner: postgres
--

Create Database "crawler";

\connect crawler postgres

--
--
-- Name: DATABASE "crawler" Type: COMMENT Owner: 
--

COMMENT ON DATABASE "crawler" IS 'link database for a Web crawler.';


create table link
   (source 	text not null,
    target 	text not null,
    visited	timestamp with time zone,
    primary key	(source, target)
	);

--insert into link values('http://www.cs.usu.edu/~lim/index.html','http://www.cs.usu.edu/~lim/publication.html',current_timestamp);
insert into link values('http://www.cs.usu.edu/~lim/index.html','http://www.cs.usu.edu/~lim/publication.html',to_timestamp('00010101','YYYYMMDD'));