14.05.2014 17:48, Vlad Khorsun wrote: >> 10.05.2014 14:03, Vlad Khorsun wrote: >> If I'm not mistaken, these repeating index entries works as a reference >> counters and > > Nope. A-A...A-B will produce two index entries
Right. And it means that there are two _series_ of versions: one with A other with B. >> allow to stop using staying list for indexes even in current code for the >> same reason as >> for blobs: three versions are enough for decision making. > > Not really. While A-B-A is not possible for blobs (as we agreed > recently), but it is usual > case for index keys. Let's look at more interesting case: A-B-A-B. In this case there will be four index entries, two for A and two for B. Now, for example, we rollback last version B, leaving A-B-A. If we collect full staying list, removing of the B index node will be prevented, leaving us with two B index nodes. If we take into account only nearest version, B node will be removed and for resulting chain A-B-A we will have in index two A nodes and _one_ B node, which is a right result. The same way you can check that removing any version from the middle of the chain will leave right number of nodes if you use for staying list only two neighbor versions. -- WBR, SD. ------------------------------------------------------------------------------ "Accelerate Dev Cycles with Automated Cross-Browser Testing - For FREE Instantly run your Selenium tests across 300+ browser/OS combos. Get unparalleled scalability from the best Selenium testing platform available Simple to use. Nothing to install. Get started now for free." http://p.sf.net/sfu/SauceLabs Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
