Dmitry Sytkov sytkov

Эта версия статьи устарела. Новая версия статьи перенесена по адресу: https://github.com/codedokode/pasta/blob/master/db/trees.md

Как хранить в БД древовидные структуры

Те, кто знают английский, могут сразу перейти сюда: http://stackoverflow.com/questions/4048151/what-are-the-options-for-storing-hierarchical-data-in-a-relational-database

Древовидные структуры - это такие структуры, где есть родители и дети, например, каталог товаров:

I've found the best way around needing sudo for global npm installs in Ubuntu is to use an .npmrc file and set a prefix for where npm installs things, then add that location to your PATH. This allows you to npm -g without sudo. With this setup I'm running ampersand's CLI without issue (and avoiding the need to sudo npm in general).

If you have any global modules installed, they should be uninstalled first so they are removed from the PATH. List all globally installed npm modules by running:

sudo npm -g ls -depth 0

When builing large strings with lots of concatenations in PL/SQL, custom approach like "use varchar2(32000) buffer to reduce the number of dbms_lob calls" makes sense even for Oracle 12.1.0.2.0.

The response time improvement is 4..300+ times :) depending on the DB version and API you use.

Note that simple v_clob || TO_CHAR (SYSTIMESTAMP) || ', ' ==> v_clob || TO_CLOB(TO_CHAR (SYSTIMESTAMP) || ', ') trick (note the extra to_clob) makes 24 times improvement for 11g. The trick is bad for 12c where results in 1.5x degradation.

The code was published 4 year ago as an answer to "How to Quickly Append VARCHAR2 to CLOB": http://www.talkapex.com/2009/06/how-to-quickly-append-varchar2-to-clob.html?showComment=1343235921606#c9077980873875311325

	#!/bin/bash

	# Recursive file convertion windows-1251 --> utf-8
	# Place this file in the root of your site, add execute permission and run
	# Converts .php, .html, .css, .js files.
	# To add file type by extension, e.g. .cgi, add '-o -name ".cgi"' to the find command

	find ./ -name ".php" -o -name ".html" -o -name ".css" -o -name ".js" -type f \|
	while read file
	do

	(use 'codegen)
	(use 'clojure.pprint)


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	TTree3Element
	ID integer
	;Position integer
	Sort string
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	<?php

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	* Ajax Connector
	*
	* @package mypackage
	*/
	$validActions = array(
	'web/data/delete',
	'web/data/edit'

	data:text/html, <style type="text/css">.e{position:absolute;top:0;right:0;bottom:0;left:0;}</style><div class="e" id="editor"></div><script src="http://d1n0x3qji82z53.cloudfront.net/src-min-noconflict/ace.js" type="text/javascript" charset="utf-8"></script><script>var e=ace.edit("editor");e.setTheme("ace/theme/monokai");e.getSession().setMode("ace/mode/ruby");</script>
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	For other language: Instead of `ace/mode/ruby`, Use

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	Python -> `ace/mode/python`
	C/C++ -> `ace/mode/c_cpp`
	Javscript -> `ace/mode/javascript`
	Java -> `ace/mode/java`
	Scala- -> `ace/mode/scala`

	import org.junit.Before;
	import org.junit.Test;

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	import static org.junit.Assert.*;

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	import org.junit.Before;
	import org.junit.Test;

	import java.util.*;

	import static org.hamcrest.Matchers.*;
	import static org.hamcrest.CoreMatchers.is;
	import static org.junit.Assert.*;