SEO: Allowing crawler to index all pages when only few are visible at a time - seo

Question

I'm working on improving the site for the SEO purposes and hit an interesting issue. The site, among other things, includes a large directory of individual items (it doesn't really matter what these are). Each item has its own details page, which is accessed via
http://www.mysite.com/item.php?id=item_id
or
http://www.mysite.com/item.php/id/title
The directory is large - having about 100,000 items in it. Naturally, on any of the pages only a few items are listed. For example, on the main site homepage, there are links to about 5 or 6 items, from some other page there links to about a dozen different items, etc.
When real users visits the site, they can use search form to find item by keyword or location - so there would be a list produced matching their search criteria. However when, for example, a google crawler visits the site, it won't even attempt to put a text into the keyword search field and submit the form. Thus as far as the bot is concern, after indexing the entire site, it has covered only a few dozen items at best. Naturally, I want it to index each individual item separately. What are my options here?
One thing I considered is to check the user agent and IP ranges and if the requestor is a bot (as best I can say), then add a div to the end of the most relevant page with links to each individual item. Yes, this would be a huge page to load - and I'm not sure how google bot would react to this.
Any other things I can do? What are best practices here?
Thanks in advance.

Answer 1

One thing I considered is to check the user agent and IP ranges and if
the requestor is a bot (as best I can say), then add a div to the end
of the most relevant page with links to each individual item. Yes,
this would be a huge page to load - and I'm not sure how google bot
would react to this.
That would be a very bad thing to do. Serving up different content to the search engines specifically for their benefit is called cloaking and is a great way to get your site banned. Don't even consider it.
Whenever a webmaster is concerned about getting their pages indexed having an XML sitemap is an easy way to ensure the search engines are aware of your site's content. They're very easy to create and update, too, if your site is database driven. The XML file does not have to be static so you can dynamically produce it whenever the search engines request it (Google, Yahoo, and Bing all support XML sitemaps). You can find out mroe about XML sitemaps at sitemaps.org.
If you want to make your content available to search engines and want to benefit from semantic markup (i.e. HTML) you should also make sure your all of content can be reached through hyperlinks (in other words not through form submissions or JavaScript). The reason for this is twofold:
The anchor text in the links to your items will contain the keywords you want to rank well for. This is one of the more heavily weighted ranking factors.
Links count as "votes", especially to Google. Links from external websites, especially related websites, are what you'll hear people recommend the most and for good reason. They're valuable to have. But internal links carry weight, too, and can be a great way to prop up your internal item pages.
(Bonus) Google has PageRank which used to be a huge part of their ranking algorithm but plays only a small part now. But it still has value and links "pass" PageRank to each page they link to increasing the PageRank of that page. When you have as many pages as you do that's a lot of potential PageRank to pass around. If you built your site well you could probably get your home page to a PageRank of 6 just from internal linking alone.
Having an HTML sitemap that somehow links to all of your products is a great way to ensure that search engines, and users, can easily find all of your products. It is also recommended that you structure your site so more important pages are closer to the root of your website (home page) and then as you branch out gets to sub pages (categories) and then to specific items. This gives search engines an idea of what pages are important and helps them organize them (which helps them rank them). It also helps them follow those links from top to bottom and find all of your content.
Each item has its own details page, which is accessed via
http://www.mysite.com/item.php?id=item_id
or
http://www.mysite.com/item.php/id/title
This is also bad for SEO. When you can pull up the same page using two different URLs you have duplicate content on your website. Google is on a crusade to increase the quality of their index and they consider duplicate content to be low quality. Their infamous Panda Algorithm is partially out to find and penalize sites with low quality content. Considering how many products you have it is only a matter of time before you are penalized for this. Fortunately the solution is easy. You just need to specify a canonical URL for your product pages. I recommend the second format as it is more search engine friendly.
Read my answer to an SEO question at the Pro Webmaster's site for even more information on SEO.

Answer 2

I would suggest for starters having an xml sitemap. Generate a list of all your pages, and submit this to Google via webmaster tools. It wouldn't hurt having a "friendly" sitemap either - linked to from the front page, which lists all these pages, preferably by category, too.
If you're concerned with SEO, then having links to your pages is hugely important. Google could see your page and think "wow, awesome!" and give you lots of authority -- this authority (some like to call it link juice" is then passed down to pages that are linked from it. You ought to make a hierarchy of files, more important ones closer to the top and/or making it wide instead of deep.
Also, showing different stuff to the Google crawler than the "normal" visitor can be harmful in some cases, if Google thinks you're trying to con it.
Sorry -- A little bias on Google here - but the other engines are similar.