Managing UniData Metadata

In this section:

When the server accesses a data source, it needs to know how to interpret the data stored there. For each object the server will access, you create a synonym that describes its structure and the server mapping of the data types.


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Identifying the Adapter

How to:

The SUFFIX attribute in the Master File identifies the adapter needed to interpret a request. Use the SUFFIX value SQLUND to identify the Adapter for UniData.



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Syntax: How to Identify the Adapter
FILE[NAME]=file, SUFFIX=SQLUND [,$]

where:

file

Is the file name for the Master File. The file name without the .mas extension can consist of a maximum of eight alphanumeric characters. The file name should start with a letter and be representative of the table or view contents. The actual file must have a .mas extension, but the value for this attribute should not include the extension.

SQLUND

Is the value for the adapter.


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Accessing Database Tables

If you choose to access a remote third-party table using UniData, you must locally install the RDBMS UniData Driver.

The Server can access third-party database tables across the UniData network. You must specify a URL for the data source and, possibly, a user ID and/or password for the database you are accessing. You can define these parameters in either the server global profile or in a user profile.


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Creating Synonyms

How to:

Reference:

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Synonyms define unique names (or aliases) for each object that is accessible from the server. Synonyms are useful because they hide the underlying data source location and identity from client applications. They also provide support for extended metadata features of the server, such as virtual fields and additional security mechanisms.

Using synonyms allows an object to be moved or renamed while allowing client applications to continue functioning without modification. The only modification required is a redefinition of the synonym on the server. The result of creating a synonym is a Master File and an Access File, which represent the server metadata.

Note: If you are creating a synonym for a UniData data source, you must first add the syntax SET SYNONYM=BASIC to the edasprof.prf file.



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Procedure: How to Create a Synonym

To create a synonym, you must have previously configured the adapter. You can create a synonym from the Applications or Adapters pages of the Web Console.

  1. From the Web Console menu bar, click Applications.

    The Applications page opens.

  2. Click the New button and select Synonym from the drop-down menu.

    The Select adapter to configure or Select connection to create synonym pane opens.

  3. Click a connection for the configured adapter.

    The first of a series of synonym creation panes opens.

  4. Enter values for the parameters required by the adapter as described in the synonym creation parameters reference.
  5. After entering the parameter values, click Create Synonym.

    The Status pane indicates that the synonym was created successfully.

The synonym is created and added under the specified application directory.

Note:



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Reference: Synonym Creation Parameters for UniData

The following list describes the synonym creation parameters for which you can supply values.

Restrict Object Type to

Restrict candidates for synonym creation based on the selected object type(s): Tables, Views, External SQL Scripts, and any other supported objects.

Choosing External SQL Scripts from the drop-down list enables you to represent an SQL Query as a synonym for read-only reporting. A Synonym candidate can be any file that contains one (and only one) valid SQL Query and does not contain end-of-statement delimiters (";" or "/") and comments.

Depending on the adapter, you can further restrict your search by choosing check boxes for listed objects.

Filter by Owner/Schema and Object name

Selecting this option adds the Owner/Schema and Object Name parameters to the screen.

  • Owner/Schema. Type a string for filtering the selection, inserting the wildcard character (%) as needed at the beginning and/or end of the string. For example, enter: ABC% to select tables or views whose owner/schema begin with the letters ABC; %ABC to select tables or views whose owner/schema end with the letters ABC; %ABC% to select tables or views whose owner/schema contain the letters ABC at the beginning, middle, or end.
  • Object name. Type a string for filtering the object names, inserting the wildcard character (%) as needed at the beginning and/or end of the string. For example, enter: ABC% to select all objects whose names begin with the letters ABC; %ABC to select all whose names end with the letters ABC; %ABC% to select all whose names contain the letters ABC at the beginning, middle, or end.
Location of External SQL Scripts

xIf you specify External SQL Scripts in the Restrict Object type to field, these additional fields are displayed.

The following standard naming conventions apply for UNIX, IBM i IFS, and z/OS HFS:

  • In the Base Location field, specify the physical directory location of the file that contains the SQL Query. You can type a directory name or click on the ellipsis. This opens the Select Base Location dialog box.
  • In the Document Name field, enter the file name with or without wild card characters.
  • In the Document Extension field, enter the extension of the script files to filter the list of candidates.

On IBM i, you can use alternative IFS naming conventions to access library members. The following entry illustrates this method:

  • In the Base Location field, enter:
    /QSYS.LIB/MYLIBRARY.LIB/MYSRC.FILE
  • The Document Extension is understood to be MBR. You can enter this value explicitly or leave the input box blank.

During synonym generation, the adapter issues native API calls to obtain a list of elements in the select list and builds the Master File with a field for each element. The generated Access File references the location of the SQL script in the DATASET attribute, which contains the full path, including the name and extension of the file containing the SQL Query. For example,

DATASET=/ul/home2/apps/report3.sql

When a WebFOCUS report is created, the SQL Query is used to access data.

Cardinality

Select the Cardinality check box to reflect the current cardinality (number of rows or tuples) in the table during metadata creation. Cardinality is used for equi-joins. The order of retrieval is based on the size (cardinality) of the table. Smaller tables are read first.

If the cardinality of the tables to be used in the application are dynamic, it may not be beneficial to choose this setting.

Build cluster using foreign keys (deprecated)

You can select the Build cluster using foreign keys check box to include within this synonym every table related to the current table by a foreign key. However, this option has been deprecated, as the recommended way to create a cluster is by using the Synonym Editor. The resulting multi-table synonym describes all of the foreign key relationships of this table.

Dynamic columns

To specify that the Master File created for the synonym should not contain column information, select the Dynamic columns check box.

If this option is selected, column data is retrieved dynamically from the data source at the time of the request.

For Subquery

Only available when External SQL Scripts is selected from the Restrict objects type to drop-down menu. When selected, a SUBQUERY keyword is added to the Access File of the generated synonym. If the corresponding SQL string has valid syntax that can be used in the FROM statement of the generated SQL (what is known as a Derived Table), then the SQL SCRIPT will be processed as a subquery embedded into a FROM clause. This usage allows for more flexibility. For example, the synonym can be used as a target for a JOIN.

If the SQL SCRIPT has parameter markers, such as ? or :, or the syntax contains constructs that are invalid for a derived table, for example ORDER BY, then this keyword should not be selected. At runtime, if SUBQUERY=Y is present and it is determined that the SQL SCRIPT cannot be used in the FROM statement, the setting will be ignored, and a FOC1782 warning message will be issued. The default is selected (SUBQUERY=Y).

Application

Select an application directory. The default value is baseapp.

Prefix/Suffix

If you have tables with identical table names, assign a prefix or a suffix to distinguish them. For example, if you have identically named human resources and payroll tables, assign the prefix HR to distinguish the synonyms for the human resources tables. Note that the resulting synonym name cannot exceed 64 characters.

If all tables and views have unique names, leave the prefix and suffix fields blank.

Customize data type mappings

To change the data type mappings from their default settings, select this check box. The customizable mappings are displayed.

For information about customizable mappings, see Data Type Support.

Update or Create Metadata

Select Create to overwrite any existing synonym with the same fully-qualified name, or Update to synchronize the metadata with an existing synonym. If you select Update, the next screen will show a list of attributes from the DBMS catalog that you can check to allow attributes from the DBMS catalog to override attributes from the existing synonym.

Overwrite Existing Synonyms

To specify that this synonym should overwrite any earlier synonym with the same fully qualified name, select the Overwrite existing synonyms check box.

Note: The connected user must have operating system write privileges in order to recreate a synonym.

Default Synonym Name

This column displays the name that will be assigned to each synonym. To assign a different name, replace the displayed value.

Owner/Schema

The user account that created the object or a collection of objects owned by a user.

Table name

Is the name of the underlying object.

Type

The object type (Table, View, and so on).

Select tables

Select tables for which you wish to create synonyms:

  • To select all tables in the list, select the Select All check box.
  • To select specific tables, select the corresponding check boxes.


Example: Sample Generated Synonym

An Adapter for UniData synonym comprises a Master File and an Access File. This is a synonym for the table nf29004.

Master File nf29004.mas

FILE=DIVISION, SUFFIX=SQLUND ,$
SEGNAME=SEG1_4, SEGTYPE=S0 ,$
FIELD=DIVISION4,    DIVISION4, I9, I4, MISSING=OFF ,$
FIELD=DIVISION_NA4, DIVISION4, I9, I4, MISSING=OFF ,$
FIELD=DIVISION_HE4, DIVISION4, I9, I4, MISSING=OFF ,$

Access File nf29004.acx

SEGNAME=SEG1_4,TABLENAME=EDAQA.NF29004,
CONNECTION=CON1,KEYS=1,WRITE=YES,$


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Reference: Access File Keywords

This chart describes keywords in the Access File.

Keyword

Description

SEGNAME

Value must be identical to the SEGNAME value in the Master File.

TABLENAME

Identifies the UniData table. The value assigned to this attribute can include the name of the owner (also known as schema) and the database link name as follows:

TABLENAME=[owner.]table                      
CONNECTION

Indicates a previously declared connection. The syntax is:

CONNECTION=connection                      

CONNECTION=' ' indicates access to the local data source.

Absence of the CONNECTION attribute indicates access to the default database server.

KEYS

Indicates how many columns constitute the primary key for the table. Corresponds to the first n fields in the Master File segment.

See the KEY attribute below for information about specifying the key fields without having to describe them first in the Master File.

KEY

Specifies the columns that participate in the primary key without having to describe them as the first fields in the Master File. The syntax is:

KEY=fld1/fld2/.../fldn
WRITE

Specifies whether write operations are allowed against the table.

KEYFLD
IXFLD

Supply the names of the primary key and foreign key fields that implement the relationships established by the multi-table Master File. Together, KEYFLD and IXFLD identify the field shared by a related table pair.

  • KEYFLD is the FIELDNAME of the common column from the parent table.
  • IXFLD is the FIELDNAME of the common column from the related table.

KEYFLD and IXFLD must have the same data type. It is recommended, but not required, that their lengths also be the same.

Note: An RDBMS index on both the KEYFLD and IXFLD columns provides the RDBMS with a greater opportunity to produce efficient joins. The columns must have the same data type. If their length is the same, the RDBMS handles the join more efficiently.



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Reference: Managing Synonyms

Once you have created a synonym, you can right-click the synonym name in the Adapter navigation pane of either the Web Console or the Data Management Console to access the following options.

Option

Description

Open

Opens the Master File for viewing and editing using a graphical interface. If an Access file is used it will be also available.

Edit as Text

Enables you to view and manually edit the Master File synonym.

Note: To update the synonym, it is strongly recommended that you use the graphical interface provided by the Open option, rather than manually editing the Master File.

Edit Access File as Text

Enables you to view and manually edit the Access File synonym.

Note: This option is available only when an Access File is created as part of the synonym.

Sample Data

Retrieves up to 20 rows from the associated data source.

Data Profiling

Data Profiling provides the data characteristics for synonym columns.

Alphanumeric columns provide the count of distinct values, total count, maximum, minimum, average length, and number of nulls.

Numeric columns provide the count of distinct values, total count, maximum, minimum, average value, and number of nulls.

Refresh Synonym (if applicable)

Regenerates the synonym. Use this option if the underlying object has been altered.

Data Management

Followed by these options, if applicable:

Recreate DBMS Table. Recreates the data source table. You are asked to confirm this selection before the table is regenerated. (Note that the table will be dropped and recreated. During the process, data may be lost.)

Delete All Data. Deletes all existing data. You are asked to confirm this selection before the data is deleted.

Drop Table. Drops the table so that it is removed from the DBMS.

Insert Sample Data. Inserts specified number of sample records, populating all fields with counter values.

Show/Modify Data. Opens a window that shows the data in the data source with buttons you can click to insert values, filter values, reload the data source, and customize the view.

Reorganize. Recreates the data source table preserving original data.

Note: This option is not available in the Web Console.

Impact Analysis

Generates a report showing where this synonym is stored and used, with links to the synonym instances. Impact Analysis reports enable you to evaluate changes before they are made by showing which components will be affected. See the Server Administration manual for details about Impact Analysis reports.

Dependencies Analysis

Generates a report showing information about the synonym and other synonyms and objects that are referenced within it.

Copy

Copies the synonym to the clipboard.

Delete

Deletes the synonym. You are asked to confirm this selection before the synonym is deleted.

Cut

Deletes the synonym and places it on the clipboard.

Privileges

Shows the security subjects on the server and the privileges they have to this synonym.

Properties

Displays the properties of the synonym, including physical location, last modified date, description, and privileges.



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Data Type Support

Data types are specific to the underlying data source.


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Changing the Precision and Scale of Numeric Columns

How to:

You can alter the length and scale of numeric columns returned by a SELECT request to the server by creating different specifications in your login profile or in a stored procedure. The conversion settings are reflected in the Master File in the USAGE and ACTUAL formats of the fields generated by CREATE SYNONYM. This affects how the fields are processed and formatted by the server.

Tip: You can change this setting manually or from the Web Console.



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Syntax: How to Override the Default Precision and Scale
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ENGINE SQLUND SET CONVERSION RESET
ENGINE SQLUND SET CONVERSION format RESET
ENGINE SQLUND SET CONVERSION format [PRECISION precision [scale]]
ENGINE SQLUND SET CONVERSION format [PRECISION MAX]

where:

SQLUND

Indicates the adapter. You can omit this value if you previously issued the SET SQLENGINE command.

RESET

Returns any previously specified precision and scale values to the adapter defaults. If you specify RESET immediately following the SET CONVERSION command, all data types return to the defaults. If you specify RESET following a particular data type, only columns of that data type are reset.

format

Is any valid format supported by the data source. Possible values are:

INTEGER which indicates that the command applies only to INTEGER columns.

DECIMAL which indicates that the command applies only to DECIMAL columns.

REAL which indicates that the command applies only to single-precision floating-point columns. Only applies to DB2, CA-IDMS/SQL, Microsoft SQL Server, and Sybase.

FLOAT which indicates that the command applies only to double-precision floating-point columns.

precision

Is the precision. Must be greater than 1 and less than or equal to the maximum allowable value for the data type (see the description of MAX).

scale

Is the scale. This is valid with DECIMAL, FLOAT and REAL data types. If you do not specify a value for scale, the current scale setting remains in effect. The default scale value is 2.

If the scale is not required, you must set the scale to 0 (zero).

MAX

Sets the precision to the maximum allowable value for the indicated data type:

Data Type

MAX Precision

INTEGER

11

DECIMAL

18

REAL

9

FLOAT

20

Note: When issuing the CREATE SYNONYM command while the CONVERSION command is active in the profile, the Master File reflects the scale and length that is set by the CONVERSION command.

However, when issuing a SELECT statement, the answer set description does not use the information in the Master File. The length and scale used for the answer set description depends on whether a CONVERSION command is in effect.

If a CONVERSION command is in effect, the answer set description uses the length and scale that is set by the CONVERSION command.

If a CONVERSION command is not in effect, the answer set description uses the actual length and scale of the data.



Example: Setting the Precision and Scale Attributes

The following example shows how to set the precision attribute for all INTEGER and SMALLINT fields to 7:

ENGINE SQLUND SET CONVERSION INTEGER PRECISION 7

The following example shows how to set the precision attribute for all DOUBLE PRECISION fields to 14 and the scale attribute to 3:

ENGINE SQLUND SET CONVERSION FLOAT PRECISION 14 3

The following example shows how to set the precision attribute for all INTEGER and SMALLINT fields to the default:

ENGINE SQLUND SET CONVERSION INTEGER RESET

The following example shows how to set the precision and scale attributes for all fields to the defaults:

ENGINE SQLUND SET CONVERSION RESET

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