The first time I created my site map for Google, I did so in a txt file. It uploaded fine, and began to show Google through my site per the stats available in the account details. I then began to lose previously indexed pages in Google. I read in this forum, that some believed that adding a Google sitemap caused indexing problems with their site; and they were losing pages in the hundreds, if not thousands, from the Google index. I toyed with taking down my site map, and saw almost instant results - my pages began to show in the index within minutes afterwards. Then, after a few days, I began to see the same inconsistencies, and fluctuations in the index as before, so I added the sitmap again to my account. However, this time, I used an XML format. It seemed to give better results - quicker indexing, and more pages indexed. My question is, does anyone feel that it is better (or worse) to use one file format over the other? Is Google more inclined (algorithmically) to read and index an XML sitemap, rather than a txt site map - or are all of these occurrences typical Google anomalies? Any thoughts are greatly appreciated!
I would bet my house on the fact that google is not de-indexing you as a result of adding a sitemap. What they may be doing is using the sitemap to spider pages and then realising that some existing pages are dead or that they don't want them to be in the index so are removing them.
I decided a few weeks ago, that the site map was NOT causing the problem with the indexing and deindexing of my site. I thought I would try removing it, as a few other DP members were testing the theory for their own sites. I didn't have any html errors, or files not found in the sitemap control panel. Google has just been going through some crazy changes, I think. That is probably all that was happening; it was just cooincidence that it happened around the same time some of us began to use Google Sitemaps.
I'm with Mad4 100%... I monitor hundreds of sitemaps with Google and there haven't been any issues with de-indexing any of the sites. The XML format gives G a little more info about your site and the best parts of that is that it saves you some bandwidth (versus checking pages that never update...changefreq) and it helps them to focus on the pages you feel are most important (priority). It also lets them know which pages they need to come visit (lastmod) because their index is out of date for that page. If you're running static PHP pages (real files for each page with some PHP thrown in), I have a script that will even allow you to support the If-Modified-Since and Last-Modified HTTP headers that Google likes so much. This script won't work if you have a smarty template, because all 'pages' come through 1 file, but it's worked wonders for me on a few sites.
"If-Modified-Since" and "Last-Modified" HTTP headers are great for reducing your total bandwidth costs too, especially if you get a lot of repeat visits. The "Expires" header is another good one if you know when the page will be updated next, or conversely if you know when your page won't be updated (e.g. not for at least 24 hours). Can be really tricky to debug though - "wget -S --spider" is really useful for that. Cryo.
Having used both types, I recommend both of them. The XML version for a complete, deep index (i.e. Python generated). The TXT version to obtained a "focused" index of a small amount. But if both have the same number of pages in it, then the XML gives better results.
I usually have both. I have one XML sitemap for google to read and i have one text sitemap for my visitors to read. This is the best imo.
I also think that a XML sitemap is better for search engine because in the XML sitemap we can indicate the page's priority, the page's change frequency and we can indicate when was the page last time modified. Another thing why I think XML is better than TXT sitemaps would be that currently, there are almost 476.000 websites with xml sitemaps and only 10.100 witv txt sitemaps ( done a search on google, inurl:sitemap.txt and inurl:sitemap.xml).
XML Sitemap is best comparision to TXT format.using XML sitemap search engine spinder/crawler search the web pages priority,frequency and also show last modified date.a XML sitemap helps as far as getting indexed faster by google.
If you are using a Wordpress blog, I would recommend automating the sitemap creation through a plugin. An XML would be best.
You use you some of the extra information XML sitemaps gives, then XML sitemaps. Otherwise text sitemaps will do fine. You may want to read this sitemaps comparison article.
Both can be used for indexing purposes. But the XML site map works better and give you good results than the txt sitemap.