TiledColumnStMan.h

TiledColumnStMan is a derivation from TiledStMan, the abstract tiled storage manager class. A description of the basics of tiled storage managers is given in the Tables module description.

TiledColumnStMan allows the user to create a tiled hypercube for an entire data column and extend it in an automatic way. It is meant to be used for fixed shaped data which have to be accessed in various directions.

The TiledColumnStMan has the following (extra) properties:

Addition of a row results in the extension of the hypercube. The data cells in all rows have to have the same shape. Therefore the columns stored by a TiledColumnStMan storage manager have to be fixed shaped (i.e. FixedShape attribute set in their column descriptions).
Coordinates for the hypercubes can be defined and (of course) their shapes have to match the hypercube shape. Their values have to be put explicitly (so it is not possible to define them via an extendHypercube call like in TiledDataStMan).
The tile shape of the hypercube has to be defined by means of the TiledColumnStMan constructor.

Motivation

This tiled storage manager does not require any special action (like calling add/extendHypercube) when used with a column containing equally shaped arrays.

Example

  // Define the table description and the columns in it.
  TableDesc td ("", "1", TableDesc::Scratch);
  td.addColumn (ArrayColumnDesc<float>  ("RA", 1));
  td.addColumn (ArrayColumnDesc<float>  ("Dec", 1));
  td.addColumn (ScalarColumnDesc<float> ("Velocity"));
  td.addColumn (ArrayColumnDesc<float>  ("Image", 2));
  // Define the 3-dim hypercolumn with its data and coordinate columns.
  // Note that its dimensionality must be one higher than the dimensionality
  // of the data cells.
  td.defineHypercolumn ("TSMExample",
			  3,
			  stringToVector ("Image"),
			  stringToVector ("RA,Dec,Velocity"));
  // Now create a new table from the description.
  SetupNewTable newtab("tTiledColumnStMan_tmp.data", td, Table::New);
  // Create a TiledColumnStMan storage manager for the hypercolumn
  // and bind the columns to it.
  // The tile shape has to be specified for the storage manager.
  TiledColumnStMan sm1 ("TSMExample", IPosition(3,16,32,32));
  newtab.bindAll (sm1);
  // Create the table.
  Table table(newtab);
  // Define the values for the coordinates of the hypercube.
  Vector<float> raValues(512);
  Vector<float> DecValues(512);
  indgen (raValues);
  indgen (decValues, float(100));
  ArrayColumn<float> ra (table, "RA");
  ArrayColumn<float> dec (table, "Dec");
  ScalarColumn<float> velocity (table, "Velocity");
  ArrayColumn<float> image (table, "Image");
  Cube<float> imageValues(IPosition(2,512,512));
  indgen (imageValues);
  // Write some data into the data columns.
  uInt i;
  for (i=0; i<64; i++) {
      table.addRow();
	image.put (i, imageValues);
      // The RA and Dec have to be put only once, because they
      // are the same for each row.
      if (i == 0) {
          ra.put (i, raValues);
          dec.put (i, decValues);
      }
      velocity.put (i, float(i));
  }

Member Description

TiledColumnStMan (const String& hypercolumnName, const IPosition& tileShape, uInt maximumCacheSize = 0)
TiledColumnStMan (const String& hypercolumnName, const Record& spec)

Create a TiledDataStMan storage manager for the hypercolumn with the given name. The columns used should have the FixedShape attribute set. The hypercolumn name is also the name of the storage manager. The given tile shape will be used. The given maximum cache size in bytes (default is unlimited) is persistent, thus will be reused when the table is read back. Note that the class ROTiledStManAccessor allows one to overwrite the maximum cache size temporarily. Its description contains a discussion about the effects of setting a maximum cache.
The constructor taking a Record expects fields in the record with the name of the arguments in uppercase. If not defined, their default value is used.

~TiledColumnStMan()

virtual DataManager* clone() const

Clone this object. It does not clone TSMColumn objects possibly used.

virtual Bool canAccessColumn (Bool& reask) const

TiledColumnStMan can always access a column.

virtual String dataManagerType() const

Get the type name of the data manager (i.e. TiledColumnStMan).

virtual Record dataManagerSpec() const

Record a record containing data manager specifications.

static DataManager* makeObject (const String& dataManagerType, const Record& spec)

Make the object from the type name string. This function gets registered in the DataManager "constructor" map.

TiledColumnStMan()

Create a TiledColumnStMan. This constructor is private, because it should only be used by makeObject.

void addRow (uInt nrrow)

Add rows to the storage manager. This will extend the hypercube.

virtual TSMCube* getHypercube (uInt rownr)

Get the hypercube in which the given row is stored.

virtual TSMCube* getHypercube (uInt rownr, IPosition& position)

Get the hypercube in which the given row is stored. It also returns the position of the row in that hypercube.

virtual void setupCheck (const TableDesc& tableDesc, const Vector<String>& dataNames) const

Check if the hypercolumn definition fits this storage manager.

virtual Bool flush (AipsIO&, Bool fsync)

Flush and optionally fsync the data. It returns a True status if it had to flush (i.e. if data have changed).

virtual void create (uInt nrrow)

Let the storage manager create files as needed for a new table. This allows a column with an indirect array to create its file.

virtual void readHeader (uInt nrrow, Bool firstTime)

Read the header info.