Re: guidance for using TTreeSQL ?

HI Rob,

Both problems were unexpected and have now been fixed in the trunk and in the v5.28 patch branch.

The temporary table issue is due to the fact that mysql does not give access a list of those table the easy way (i.e. show table does not show them). The GetColumnIndice was an unfortunate oversight when reading table that has not been created by TTreeSQL.

Cheers,
Philippe.

On 2/17/11 10:28 AM, Rob Mahurin wrote:
> Hi,
>
> I have some data in a mysql database. I'd like to poke around in this
> data using root trees. I can do this by
>
> $ mysql< query.sql> data.txt
> $ vim data.txt ## fixup the header line
> $ root -l
> root[] TTree *t = new TTree;
> root[] t->ReadFile("data.txt")
>
> It looks like I should be able to use TTreeSQL:
>
> root[] TSQLServer* serv =
> TSQLServer::Connect("mysql://127.0.0.1/db", user, pass)
> root[] TSQLStatement* stmt = serv->Statement(
> "create temporary table data as ...")
> root[] stmt->Process()
> (Bool_t)1
> root[] TTreeSQL data(serv,"db","data")
>
> This fails completely: data.Print() says the tree has no branches and
> no entries.
>
> If I try to read a permanent table, TTreeSQL figures out its size, but
> none of its data:
>
> root[] TSQLStatement* stmt = serv->Statement(
> "create table foo as ...")
> root[] stmt->Process()
> (Bool_t)1
> root[] TTreeSQL foo(serv, "test", "foo")
> Error in<TTreeSQL::GetColumnIndice>: Error finding column 0 analyses__analyses
> root[] foo
> (class TTreeSQL)263684320
> root[] foo.Print()
> ******************************************************************************
> *Tree :foo : Database read from table: foo *
> *Entries : 172 : Total = 1287 bytes File Size = 0 *
> * : : Tree compression factor = 1.00 *
> ******************************************************************************
> *Br 0 :analyses : analyses/I *
> *Entries : 172 : Total Size= 490 bytes One basket in memory *
> *Baskets : 0 : Basket Size= 32000 bytes Compression= 1.00 *
> *............................................................................*
> *Br 1 :runlet_id : runlet_id/I *
> *Entries : 172 : Total Size= 490 bytes One basket in memory *
> *Baskets : 0 : Basket Size= 32000 bytes Compression= 1.00 *
> *............................................................................*
> root[] foo.Scan()
> ************************************
> * Row * analyses * runlet_id *
> ************************************
> * 0 * 0 * 0 *
> * 1 * 0 * 0 *
> * 2 * 0 * 0 *
>
> Maybe I should try to fill:
>
> root[] foo.Fill()
> Error in<TTreeSQL::GetColumnIndice>: Error finding column 0 analyses__analyses
> Error in<TTreeSQL::GetColumnIndice>: Error finding column 0 runlet_id__runlet_id
> Error in<TTreeSQL::Fill>: CheckBranch for analyses failed
> Error in<TTreeSQL::Fill>: CheckBranch for runlet_id failed
> Error in<TTreeSQL::GetColumnIndice>: Error finding column 0 analyses__analyses
> Error in<TTreeSQL::GetColumnIndice>: Error finding column 0 runlet_id__runlet_id
> (Int_t)(-1)
>
> I can verify from other queries that the tables are being created and
> filled correctly in the database. I get identical failures under
> root_v5.26/00 on a Linux cluster and under root_v5.28/00 on MacOS 10.5
> (connecting to the same server, running mysql "5.0.77-log Source
> distribution"). Is TTreeSQL just broken? Or am I missing something
> obvious?
>
> Thanks,
> Rob
>
Received on Thu Feb 24 2011 - 20:05:23 CET