Tables

Tables are the objects in which databases store data. Pervasive PSQL contains two types of tables: data and system. Data tables are user-created. Newly created ones are empty and must be populated with data. System tables are created and populated as required by the Pervasive PSQL database management system.

Data Tables

Refer to the chapter Table Editor for a detailed discussion of data tables. That chapter also contains the tasks pertaining to tables, such as creating one, deleting one, working with columns, foreign keys, and so forth.

Note
To create a table in a database, database security must be turned off or you must have access rights to create tables.

System Tables

System tables appear in the Pervasive PSQL Explorer under the "System Objects" node. You may view properties of them as explained in To view properties of a table.

Table Properties

Table properties provides information about the table. Separate tabs let you view general properties, columns information, and indexes information. The following table describes the parameters listed on the "General" tab.

Table 3-4 Table Properties on General Tab
Parameter	Description
Table Name	Shows the name of the table as it appears in the database definition.
Table Location	Shows the physical location of the data file associated with the table.
Dictionary Path	Shows where the database's DDF files are located.
File Version	Shows the file format version of the data file.
Record Length	Shows the length of the data file's records.
Page Size	Shows the page size (in bytes) of the data file. The page size determines the maximum number of index segments that can be defined in a table.
Number or Records	Shows the number of records currently contained in the data file.
Number of Indexes	Shows the number of indexes defined for the table.
Number of Duplicate Pointers (Ptrs)	Shows the number of linked duplicate indexes that can be added.
Number of Unused Pages	Shows the number of pre-allocated pages available. If pre-allocation is enabled, the MicroKernel pre-allocates a specified number of pages when it creates the data file. Pre-allocation guarantees that disk space for the data file is available when the MicroKernel needs it.
Variable Records	Shows whether the data file contains variable-length records.
Variable Record Blank Truncation	Shows whether blank truncation is enabled. If it is, the MicroKernel truncates the blanks in variable-length records. Blank truncation is applicable only if the Variable Records statistic is Yes and Data Compression is set to No.
Data Compression	Shows whether data compression is enabled. If it is, the MicroKernel compresses each record it inserts into the data file.
Key Only File	Shows the name of the key-only file for the table, if any. A key-only file contains no data records but serves as an index to other Btrieve files.
Index Balancing	Shows whether balanced indexing is enabled.
FreesSpace Threshold	Shows a percentage (5%, 10%, 20% or 30%) if the data file has a free space threshold. The database engine stores the variable-length portions of records on their own pages (called variable pages), separate from the fixed-length portions (which are stored on data pages). The database engine uses the threshold to determine whether to add data to an existing variable page or to create a new one. A higher free space threshold reduces fragmentation of variable-length records across several pages but uses more disk space.
Uses Alternate Collating Sequence	Shows whether the table uses an alternate collating sequence for sorting.
System Data Key	Shows whether the data file has system data keys enabled.

To view properties of a table

Expand the list of tables for the database (click the icon to the left of the Tables node in Pervasive PSQL Explorer).

Right-click on the desired table.

Click Properties.

Tip
You can use the table properties to view a list of the indexed columns for the table.