Radius search in PostgreSQL may come in employing a light and/or a much more sophisticated version. This article discusses the light one, namely the cube and the earth distance extensions, most probably sufficient for the web user’s getting here and there requirements. earth distance, depending on cube, assumes the earth to be perfectly spherical, anyone demanding a higher accuracy level, especially for the mountainous parts, may take a look at the PostGIS project.
Although radius search, the light variety, will be up fast and performing well, there may be some mantrap around, for the ones who prefer to read documentation the easy way too. First of all, PostgreSQL: Documentation: 9.1: earthdistance indicates that the point-based earth distance calculation is hard-wired to statute miles in units. You may use this circumstance to your advantage, like datachomp did in Radius Queries in Postgres, as long as you know what you’re doing. Second to that, taking on the alternate cube-based earth distance calculation, the earth_box function, accepting a lat/long and a radius on input, may return locations farther than the actual radius given (documented alike). This is because earth_box, as the name implies, still handles a box geometry on the idealized sphere (and not some higher order circle surface). But more on that below.
Getting this far, the app itself comes up and is operable as expected. Pity is but, that the folder pane does not show up when clicking the generated launcher item (though it worked in the preview mode). The launcher item itself is nothing more than some .desktop file in (~/.local/share/applications/Browser.desktop). On inspection, we have this exec entry:
Programmatically or intercepted by forced cursor sharing, sql where clause actual values shall always be bound to variable placeholders and never / no longer be literally coded. You know Tom Kyte talking that story on each and every occasion, pointing out that so many sql areas got stuck in size and performance because of literal values and the resulting multitude of variants of sql statements. On the other hand, people complain about the sporadic issue that the optimizer takes wrong decisions due to one-time probing of actual values in a given session, a nightmare in 10g, much improved by adaptive cursor sharing throughout 12c meanwhile. Well, I do not want to dive into this again, what follows is just a commented recipe sql statement to inspect what actual bind values have had been in action for a (potentially) sub-optimal sql execution. Please note, that the STATISTICS_LEVEL initialization parameter takes to be greater than BASIC to have the statement deliver any data.
The statement is neither complex nor long-running, just using two perfomance views v$sql_bind_capture and v$sqlarea, resp. While v$sql_bind_capture provides for the bind names, values, capture state and time, v$sqlarea offers different ways to approach the subject, by schema or sql-id or module etc, and not at least, the raw text of the statement in question.
I’m not shure, though, whether tmp.mount.hm4: After swap.target is releated, really, because the implemented change is already present on my systems (systemd‘s). I’m much more tending to suspect widespread storage fragmentation on the swap area to cause the relatively long term swap off run-times. In addition, I almost only experienced the issue for systems that have been up for a longer number of days, say from 90 days onwards.
As being spotted on Bjoern Rost’s blog, commented by Trap, today, Oracle obviously has been backing down on the deprecation announcement of oracle restart along 12c. On metalink, see:
Withdrawn: Deprecation Announcement of Oracle Restart with Oracle Database 12c (Doc ID 1584742.1)
This is good news, accepted with delight, since we do no longer need to turn back the hands of time into the nifty-oracle-bounce-handycraft-scripts-era. In fact, I wonder how many dba’s are already comfortable with systemd service registration. I suppose, a lot of dba’s would have been resorting back to the dusty sysv configurations, using the systemd-sysv-compatibility engine, which is sort of retrofitting a car-key-starter with a car that already comes with wireless keying and just some starter button. Look around, the major share of on-premise oracle database installations is still single instance compared to rac and even 12c-containers.