Enhanced Bibcode Access In Xamin

The recently released version 2.1.6 of Xamin has some enhanced capabilities for handling bibcode queries. For some time the web interface has allowed users to ask whether any tables have rows that index observations which are referenced in a particular article using the syntax


where xxxx is the 19 character bibcode. The new version gives a bit more feedback about which bibcode was used when such queries are made.

The zzbib table can be used to find tables and rows matching a particular bibcode in the batch interface with a syntax like

java -jar users.jar table=zzbib constraint=bibcode="'xxxx'"

java -jar users.jar table=zzbib constraint=bibcode="'2014Natur.505..378C'"
bibcode |table_name|id_fields|id
2014Natur.505..378C|rosmaster |seq_id |RP200984N00
2014Natur.505..378C|rosmaster |seq_id |RP201583N00
2014Natur.505..378C|rosmaster |seq_id |RP201584N00
2014Natur.505..378C|rosmaster |seq_id |RP201585N00
2014Natur.505..378C|rosmaster |seq_id |RP201586N00
2014Natur.505..378C|rosmaster |seq_id |RP201587N00

Number of rows: 6
Number of columns: 4

will find the rows in zzbib that reference a particular bibcode. The other fields in zzbib indicate the table, the column of the table used to id specific rows the table, and the value for that id. [Note that since the bibcode is a string parameter in the zzbib table, the bibcode must be enclosed in single quotes. The enclosing double quotes make sure that the single quotes are actually part of the parameter and not processed by the shell.]

In the new release of Xamin you can also add bibcode constraints to particular tables with the new bibcode parameter:

java -jar users.jar table=rosmaster bibcode=xxxx

We can repeat our example above but get the actual data for the ROSMASTER rows

java -jar users.jar table=rosmaster bibcode=2014Natur.505..378C
seq_id |instrument|exposure|ra |dec |name
RP201587N00|PSPCB | 7749|22 43 33.6|44 00 00|EV LAC
RP201586N00|PSPCB | 5928|22 43 07.2|44 10 12|EV LAC
RP201585N00|PSPCB | 4561|22 43 09.6|44 10 12|EV LAC
RP201584N00|PSPCB | 3854|22 43 07.2|44 12 36|EV LAC
RP201583N00|PSPCB | 3445|22 43 07.2|44 13 12|EV LAC
RP200984N00|PSPCB | 2673|22 46 50.4|44 19 48|GL 873

Number of rows: 6
Number of columns: 6

will find all the rows in rosmaster referred to in a particular bibcode. You can add additional constraints to the query if you like. In this context since we have special processing of the bibcode it need note be enclosed in quotes, but if the bibcode contains special characters like ampersand you may need to use quotes or some other mechanism to escape shell processing.

Xamin V2.2 Released

The major change to this version is that Xamin now generates preview image windows giving SkyView survey cutouts for queries that involve a single position. By default DSS and RASS cutouts are created, but this can be controlled in the Options/Query Control/Survey Img. option. The cutouts start out as 100×100 but can be resized and the image will be appropriately recomputed.

The internal release procedures have also been significantly updated but this will not affect users.

ConeSearch usage filtering

For the past several weeks we have been seeing extremely heavy usage (>~ 1 request per second) with several distinct users sending tens of thousands of cone search requests in rapid succession. Unfortunately, they generally seem to be sending a series of simultaneous requests until things back up, rather than doing one or two streams of requests waiting for one request to finish before starting another. Generally we’ve been able to respond to these requests, but the response time has been awful and the system load has made the interactive interface largely unusable.

To address this we’ve added in a filtering of input cone search requests. If we have more than two requests going on a given server for the same table, then the new request will immediately fail. Since we have two servers there may still be as many as four queries executing on the same table.

In the few hours since we’ve implemented this we’ve noted that the interactive interfaces are doing much better, though not as crisp as we might like. In the near future we will be moving the database to a much faster machine which should address these problems more definitively.

Heavy Usage

This morning we had a user making very heavy usage of Xamin sending multiple cone search requests per second. Requests piled up in the database and this slowed down the system considerably. Requests that normally took a second could take several minutes. Metadata queries in the interactive versions of Xamin would often time out so that the Web interface was not really working.
We have temporarily disabled access for this IP address.

We’ll be looking at how we can meter usage more effectively in the future and apologize to those adversely affected.