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I wonder if we could leverage existing tools to partition the 8b-row table (surprise!) that is coming in Summer2013. I am thinking about breaking that table into a small number (8-16 or so) of smaller tables, and gluing them together through list partitioning. Serge: do you think we could use your new partitioner for that? How long do you think it'd take to partition 8b row table (the input would be in a small number of databases), if we use lsst10. I guess we could hijack lsst-dev if needed. Douglas: I don't worry as much about loading, because it will be a small number of tables, but if we could use your script to simplify that'd surely be handy. The important thing to note is that whatever we do must be production quality, we can't lose any data, we can't duplicate any rows etc. Jacek On 09/03/2013 04:57 PM, Smith, Douglas A. wrote: > > This ingest discussion, is this ingest into just mysql, or > into qserv? Which would include partitioning as part > of it... > > I've got the latest qserv load script loading more than > one table at a time right now, one chunk for each cpu > on the machine. I can run tests on having that on or > off to see how long it takes to load data... > > But it would be better to try and test the creation of > myisam table without the mysql daemon, but that would > take linking to the myisam libs in some util we would need > to create, and we haven't gotten around to that... > > Douglas > > > On 09/03/2013 04:52 PM, Jacek Becla wrote: >> I am worried about 8 billion row table. Every time I asked >> in the past I was told the scale will be comparable to W13. >> 8 vs 3.9 billion will cause more than 2x more pain! >> >> >> Question: if we process in parallel and ingest into >> separate databases, will all forced sources for a given >> object always end up in the same table? If that is the >> case, I'd strongly suggest to dedupe in parallel in >> separate databases. >> >> If not, I'd compute level-2 HTM index and partition >> the tables using list partitioning: >> http://dev.mysql.com/doc/refman/5.1/en/partitioning-list.html >> and use that instead of federating mentioned earlier. >> That'd come very handy for reindexing etc. >> >> >> Jacek >> >> >> >> >> On 09/03/2013 03:42 PM, Yusra AlSayyad wrote: >>> Greg, >>> >>> Your estimate is consistent with the estimate from your 5 < RA < 7.5 run: >>> The 2.5 degree half overlap database has 447180788 forced sources. If the complete ncsa RA range is 50 degrees then 447180788*50/2.5 = 8.9 billion >>> >>> Another consideration is that we'll be will be running an update statement on the RunDeepForcedSource table to dedupe. This will join the RunDeepForcedSource table with a temporary table of duplicate IDs generated by a group by. Sorting will have to happen either in the group by or in creating an index (in addition to the regular planned index). >>> >>> -Yusra >>> >>> On Sep 3, 2013, at 3:13 PM, "Daues, Gregory Edward" <[log in to unmask]> wrote: >>> >>>> >>>> Hi Jacek, >>>> >>>> If I am estimating things properly, the scale is 8 billion rows (~ 200 sdss 'runs' >>>> each which can have 40 million rows on average). The one ingest test that I performed >>>> suggested this could be three days runtime for ingestion in serial. >>>> >>>> Greg >>>> ________________________________________ >>>> From: [log in to unmask] [[log in to unmask]] on behalf of Jacek Becla [[log in to unmask]] >>>> Sent: Tuesday, September 03, 2013 3:15 PM >>>> To: Kian-Tat Lim >>>> Cc: [log in to unmask] >>>> Subject: Re: [LSST-data] DM Status Call Minutes 2013-09-03 >>>> >>>> K-T >>>> >>>> Federating would be instantaneous (but we need to test >>>> if there are any unexpected side effects, that is human >>>> time) >>>> >>>> As to stitching vs loading: >>>> - Simon can comment how much time he saved by loading in >>>> parallel (I think if was in the order of 3-4 days) >>>> - timing for stitching is captured here: >>>> https://dev.lsstcorp.org/trac/wiki/mysqlLargeTables >>>> (short summary: <2 days). >>>> >>>> Note that we are working closely with mysql to get the >>>> 2 days down to few hours - they have a bug in the tool >>>> that rebuilds an index which prevents us from taking >>>> full advantage of available hardware. >>>> >>>> Note that these numbers are highly dependent on number >>>> of rows we are talking about. What numbers are we >>>> talking about? >>>> >>>> Jacek >>>> >>>> >>>> >>>> >>>> >>>> >>>> On 09/03/2013 12:55 PM, Kian-Tat Lim wrote: >>>>> Jacek, >>>>> >>>>>> Most painful part was stitching the tables together. >>>>>> If we have time to try doing better than a brute force, >>>>>> I'd like to experiment with using federated engine >>>>>> this time around. >>>>> The most important question is whether the time to >>>>> stitch/federate the tables was greater than it would have been to load >>>>> the tables sequentially in the first place. Do you remember? >>>>> >>>> > ######################################################################## Use REPLY-ALL to reply to list To unsubscribe from the QSERV-L list, click the following link: https://listserv.slac.stanford.edu/cgi-bin/wa?SUBED1=QSERV-L&A=1