# Errata for Graph Databases

The errata list is a list of errors and their corrections that were found after the product was released.

The following errata were submitted by our customers and have not yet been approved or disproved by the author or editor. They solely represent the opinion of the customer.

Color Key: Serious Technical Mistake Minor Technical Mistake Language or formatting error Typo Question Note Update

Version Location Description Submitted By Date Submitted
PDF Page 8
Line 4

The previous section provided a course-grained overview of the entire graph space. course-grained >> coarse-grained

Anonymous  Oct 25, 2013
Printed Page 8
Text box near top of page

"Course-grained overview" should be changed to "coarse-grained overview."

Jeff Tyzzer  Nov 29, 2013
PDF Page 13
Bottom

The code listing in Example 2-2 at the bottom of p. 13 in the PDF is identical to the code listing in Example 2-1 above it.

Anonymous  Sep 09, 2013
PDF Page 13
4th paragraph

"Asking "who are Bob's friends?" ..." But... "Friendship isn’t always a reflexive relationship", [so we asked] the reciprocal query, which is, “who is friends with Bob?” Doesn't it mean a "symmetric relationship"?

theredpea  Oct 05, 2013
PDF Page 19
Figure 2-5

The BOSS_OF relationship is bidirectional, James is the boss of Zach and Zach is the boss of James. Surely this should be unidirectional? While the text suggests unrequited love, it does not contain any examples. The diagram states Zach is in love with both Harriet and Ingrid however the implication is that he is in love with just one.

Anonymous  Oct 05, 2013
PDF Page 19
Figure 2-5, last paragraph

The text describing figure 2-5 makes it seems the figure should have asymmetric relationships. For example, James and Zach cannot be bosses of each other (via the BOSS_OF relationship), but the relationship is symmetric. Also the mention of "love being requited" in the text does not apply since both "LOVES" relationship are symmetric. The text would make more sense if figure 2-5 was updated to reflect what the text is describing.

Byron Ruth  Nov 27, 2013
PDF Page 29
End of Cypher code block

The trailing ';' is missing from the code block. The same is true for most (but not all) subsequent blocks. Also, this being an introduction to Cypher, it should be mentioned somewhere that statements must be terminated with a semicolon.

bhmevik  Jul 21, 2013
PDF Page 35
Figure 3-4

The Database slave/master relationship from the ER diagram (Figure 3-3) is missing in Figure 3-4.

bhmevik  Jul 21, 2013
PDF Page 39
First paragraph

The first (complete) sentence on the page reads: 'For our data center example, we can read off sen&#8208; tences like “Load balancer 1 fronts the App, which consists of App Instance 1, 2, and 3, and the Database, which resides on Database Machine 1 and Database Machine 2,” and “Blade 3 runs VM 3, which hosts App Instance 3.”' These sentences do not match what the graph (and previous text) shows. For instance, there is on "App Instance" entites, only "App". And there are no "Blade" entities, and no node "VM 3".

bhmevik  Jul 21, 2013
PDF Page 46
Portugal

In the diagram, it would be preferable to indicate that both slave database are dependent from the master and not chain the dependency... The same happens p. 52

Michaël Memeteau  Oct 12, 2013
PDF Page 46
Top of the page (diagram)

In the diagram, it would be preferable to indicate that both slave database are dependent from the master and not chain the dependency... The same happens p. 52

Michaël Memeteau  Oct 12, 2013
PDF Page 50
First paragraph

The sentence 'Using WITH, we then pipe the results to the collect function, which produces a comma-delimited list of play titles:' in the first paragraph is a bit unclear to me. Is the WITH clause really piping the results to the collect() function? To me, it seems the WITH clause is needed for the ORDER BY clause, not the collect() function. For instance, if one removes the WITH and ORDER BY clauses, one gets the same result, but with a different order. (And removing only the WITH clause gives an error.)

bhmevik  Jul 21, 2013
PDF Page 52
Figure 3-8

The ALIAS_OF arrow should point from Alice to Bob, not from Bob to Alice.

bhmevik  Jul 21, 2013
PDF Page 55
Figure 3-10

There are several errors in Figure 3-10: - There are three nodes labelled 'Bob'. The right one should have been 'Davina', and the left one 'Edward'. (The top one is correct.) - The edge from the top left Email node (representing email 1) to the Davina-node is labelled TO. That should have been CC. - The CC edge from the bottom right Email node (email 3) to the Edward-node is missing its arrow, and it is partly covered by the edge from the Davina-node to the email 3-node. Also, it would have been helpful to label the Email nodes with Email_1, Email_2, etc.

bhmevik  Jul 21, 2013
PDF Page 142
lines 11-13

"To traverse a network of m steps, the cost of the indexed approach, at O(m log n), dwarfs the cost of O(m) for an implementation that uses index-free adjacency" Referring to the O(...) is a practically irrelevant point here. The problem with index-lookup is NOT that it grows as O(log N) vs O(1), which for practical purposes can be considered the same. It does NOT get significantly worse as m increases (which is indicated by the paragraph above). The important difference with index vs index-free lookup is a matter of constant ratios. In practice, for example, index lookup might cost A, while index-free lookup costs B, and the problem is that A >> B.

Anonymous  Oct 31, 2013