Change log Library_tables_Tables for AIPS++ version 1.9

A summary of the changes is available.

Change-id:  0155
Author:     Ger van Diepen
Date:       2003/08/11
Area:       Library  tables    Tables
Category:   New Code
Summary:    Addition of UPDATE, INSERT, and DELETE command to TaQL

TaQL has been extended to make it more SQL-compliant. The following has been changed: - addition of the commands: - UPDATE to update one or more columns for the selected rows. It is also possible to update an array slice. - INSERT to add and fill one or more rows to a table. - DELETE to delete one or more rows from a table. - addition of the clauses: - LIMIT to limit the number of rows selected. - OFFSET to skip the first N rows selected. Both clauses are most useful in combination with ORDERBY. For example, to select the 10 highest values. - Apart from square brackets, parentheses can also be used as set delimiters. Note 199 contains a more detailed description and some examples.

Change-id:  0165
Author:     Ger van Diepen
Date:       2005/02/16
Area:       Library  tables    Tables
Category:   New Code
Summary:    Added a virtual column engine for a TaQL expression

The virtual column engine VirtualTaQLColumn has been added to the Table System. It makes it possible to have a virtual column based on a TaQL CALC expression. The column can be a scalar or an array and can have any standard data type. For example: tab.addColumn (ScalarColumnDesc("MeanArrayCol"), VirtualTaQLColumn("mean(ArrayCol)")); As can be seen in the example the TaQL expression is passed to the constructor as a string. The expression can be as complex as one likes. Care has to be taken not to delete a column used in such an expression. The system is not robust enough (yet) to cope with that.

Change-id:  0167
Author:     Ger van Diepen
Date:       2005/04/19
Area:       Library  tables    Tables
Category:   New Code
Summary:    Added cone searching to TaQL

TaQL got an operator INCONE and a few new functions to make it possible to find sources contained in a cone. It is possible to do catalogue matching using these new functions.

Change-id:  0169
Author:     Ger van Diepen
Date:       2005/05/19
Area:       Library  tables    Tables
Category:   New Code
Summary:    Added class MappedArrayEngine

The class MappedArrayEngine has been added. It makes it possible to map the data type of a column to another data type. For instance, for accuracy it is sometimes needed to store the residual data in an MS as double precision. The imager can only read single precision data, so using this engine the column containing the residual data can be mapped to a virtual column with single precision data.

Change-id:  0170
Author:     Ger van Diepen
Date:       2005/07/04
Area:       Library  tables    Tables
Category:   New Code
Summary:    Extended TaQL with select column expressions and create table

TaQL has been extended in two ways. 1. It is now possible to specify an expression in the selection column list. If an expression is given, the resulting table is a plain table instead of a reference table. Optionally a data type can be given as well. 2. The CREATE TABLE command has been added to create a new table with 0 or more columns. Optionally specific data manager info can be given. See note 199 for more info.

Change-id:  0171
Author:     Ger van Diepen
Date:       2005/10/14
Area:       Library  tables    Tables
Category:   Change Code
Summary:    Default endian format of table is now local

The default endian format of a table has been changed from big to local. It means that on big-endian machines (e.g. SUN) the default endian format of a table is big, while on a little endian machine (e.g. Intel) it is little.