Log of /trunk/io/sql/src/TSQLObjectData.cxx
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Revision
18128 -
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Modified
Thu Mar 1 16:38:36 2007 UTC (7 years, 10 months ago) by
brun
Original Path:
trunk/sql/src/TSQLObjectData.cxx
File length: 12391 byte(s)
Diff to
previous 17621
From Sergey Linev:
1. While name of the class is changed, one should use TDirectoryFile class instead of
TDirectory at the moment, then new directory object is created.
2. Appropriate change done in non-binary part of TDirectoryFile::Streamer() that old version of
class can be read.
Revision
15512 -
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Modified
Thu Jun 22 08:21:23 2006 UTC (8 years, 7 months ago) by
brun
Original Path:
trunk/sql/src/TSQLObjectData.cxx
File length: 12358 byte(s)
Diff to
previous 15125
From Sergey Linev:
1. Implementation of TDirectory I/O for TSQLFile and TXMLFile
2. In TSQLFile identifier length is now controled.
Important for Oracle, where table or column name cannot be more than 32 symbols.
3. Adding usage of TSQLStatement class where possible.
4. Small performance improvment.
Revision
13977 -
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Modified
Wed Feb 1 18:57:41 2006 UTC (8 years, 11 months ago) by
pcanal
Original Path:
trunk/sql/src/TSQLObjectData.cxx
File length: 10250 byte(s)
Diff to
previous 13524
From Sergei Linev:
Move CreateKey from TDirectory to TFile
Here is also optimisation of SQL statements and adjustement for Oracle.
Implementation of ClassBegin()/ClassMember()/ClassEnd() methdos for TBufferSQL2 and TBufferXML.
I also implementation for ClassMemeber() method for case of "raw:data" for SQL and XML cases.
Revision
13317 -
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Modified
Tue Nov 22 20:42:37 2005 UTC (9 years, 2 months ago) by
pcanal
Original Path:
trunk/sql/src/TSQLObjectData.cxx
File length: 7691 byte(s)
Diff to
previous 13312
From Sergei:
Fix white spaces, add more comment to functions, add CVS tag lines and copyright.
It should now work for array of objects and most stl classes.
I put limitation for array size. If array with fixed size exceed limit (default 20),
array will be converted to raw data, otherwise each element of array will be presented as
single column.
Revision
13312 -
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Added
Mon Nov 21 17:38:24 2005 UTC (9 years, 2 months ago) by
pcanal
Original Path:
trunk/sql/src/TSQLObjectData.cxx
File length: 5005 byte(s)
From Sergey:
Introduce a "transparent" access to SQL data base via standard TFile interface.
The main approach that each class (but not each object) has one or two tables
with names like $(CLASSNAME)_ver$(VERSION) and $(CLASSNAME)_streamer_ver$(VERSION)
For example: TAxis_ver8 or TList_streamer_ver5
Second kind of tables appears, when some of class members can not be converted to
normalized form or when class has custom streamer.
For instance, for TH1 class two tables are required: TH1_ver4 and TH1_streamer_ver4
Most of memebers are stored in TH1_ver4 table columnwise, and only memeber:
Double_t* fBuffer; //[fBufferSize]
can not be represented as column while size of array is not known apriory.
Therefore, fBuffer will be written as list of values in TH1_streamer_ver4 table.
All objects, stored in the DB, will be registered in table "ObjectsTable".
In this there are following columns:
"key:id" - key identifier to which belong object
"obj:id" - object identifier
"Class" - object class name
"Version" - object class version
Data in each "ObjectsTable" row uniqly identify, in which table
and which column object is stored.
In normal situation all class data should be sorted columnwise.
Up to now following member are supported:
1) Basic data types
Here is everything clear. Column SQL type will be as much as possible
close to the original type of value.
2) Fixed array of basic data types
In this case n columns like fArr[0], fArr[1] and so on will be created.
If there is multidimensional array, names will be fArr2[1][2][1] and so on
3) Parent class
In this case version of parent class is stored and
data of parent class will be stored with the same obj:id in corrspondent table.
There is a special case, when parent store nothing (this is for instance TQObject).
In that case just -1 is written to avoid any extra checks if table exist or not.
4) Object as data member.
In that case object is saved in normal way to data base and column
will contain id of this object.
5) Pointer on object
Same as before. In case if object was already stored, just its id
will be placed in the column. For NULL pointer 0 is used.
6) TString
Now column with limited width like VARCAHR(255) in MySQL is used.
Later this will be improved to support maximum possible strings
7) Anything else.
Data will be converted to raw format and saved in _streamer_ table.
Each row supplied with obj:id and row:id, where row:id indicates
data, corresponding to this particular data member, and column
will contain this raw:id
See the TSQLFile documentation for more details.
example of a session saving data to a SQL data base
=====================================================
const char* dbname = "mysql://host.domain:3306/dbname";
const char* username = "username";
const char* userpass = "userpass";
// Clean data base and create primary tables
TSQLFile* f = new TSQLFile(dbname, "recreate", username, userpass);
// Write with standard I/O functions
arr->Write("arr",TObject::kSingleKey);
h1->Write("histo");
// Close connection to DB
delete f;
example of a session read data from SQL data base
=====================================================
// Open database again in read-only mode
TSQLFile* f = new TSQLFile(dbname, "open", username, userpass);
// Show list of keys
f->ls();
// Read stored object, again standard ROOT I/O
TH1* h1 = (TH1*) f->Get("histo");
if (h1!=0) { h1->SetDirectory(0); h1->Draw(); }
TObject* obj = f->Get("arr");
if (obj!=0) obj->Print("*");
// close connection to DB
delete f;
Known problems and open questions.
1) TTree is not supported by TSQLFile. There is independent development
of TTreeSQL, which allows to store trees directly in SQL database
2) TClonesArray is not tested, will be adjusted soon.
3) TDirectory cannot work. Hopefully, will (changes in ROOT basic I/O is required)
4) Streamer infos are not written to file, therefore schema evolution
is not yet supported. All eforts are done to enable this feature in
the near future
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