Kindle version of ebook contains repeated descriptions of sections, chapters, listings, etc.
For example the latest sentence in 1.4.1 is "... you set up in section 1.7.3" in PDF, but it is "... you set up in section _the section called "Installing PostGIS"_ ".
While having names of sections (here Installing PostGIS) is better than just numbers (1.7.3) it is slightly annoying to have "section the section" or "in chapter Chapter 14" and so on.

The last sentence in Section 3.3 misses link to the Appendix A - it is just the text, not the link to the chapter.

I also noticed some missing capitalisation in SQL in section 1.4.3, INSERT INTO ch01.restaurants (franchise, geom)
ST_Transform(ST_SetSRID(ST_Point(lon,lat),4326),2163) As geom
FROM ch01.restaurants_staging;

As - shouldn't it be AS?

Similarly Listing 1.6 - none of As is fully capitalised.

And some style fixes.
Section 4.1, PgAdmin III: Instead of "Via the pgAdmin interface, you can launch ..." I'd use "You can launch psql session via the pgAdmin interface ..."
4.4.1 contains "or you can download extracts of key areas such as those available at" - this sounds a bit strange, maybe "you can download extracts of key areas at various sites, for example at URL".

Listings at section 7.4.2, describing ST_histogram, miss descriptions, so the text is "Listing Listing 7.13 ``'' returned histogram for band 2 (...) As a result, the output in listing ??? returns 6 rows...".

And, the beginning of Chapter 13, about topologies: "I creat another polygon".

Hope that helps.
In many places there references such as "XREF chap_web_mapping"; I've seen them in PDF, epub, and mobi versions. Is this some error, or is this caused by lack of particular chapters, so software used to genereate ebooks puts such a string when it cannot find referenced chapter?

There is also problem with mobi (Kindle version). When I choose white text on black background, text is OK, but code examples are unreadable. White text on bright violet background is very hard to read. Is there something you could do with that?

"making it not only the most Advanced, but perhaps the most flexible and BEST relational database out there" - shouldn't it be "the most advanced .... and best...", without this strange capitalization?

Paget 9 (12 in PDF), FREE AS IN FREEDOM:
"you see the source code" -> "you can see the source code"

Page 19 (22 in PDF): 1.4.1 Digest the problem:
Here are several reasons that
might have motivated you to try to answer this question (feel free to cook up your
* A fast-food chain trying to locate a new store where supply falls short.
* A highway commissioner wanting to satisfy the needs of motorists, from whom you'll be
collecting tolls.
* A health-conscious parent who's trying to cut-down the availability of fast food in the
* A hungry traveller looking for your next meal.

There is the mixture of persons in those examples - e.g. hungry traveller looking for your next meal.