Text Tables are defined similarly to conventional tables with the added TEXT keyword:

    CREATE TEXT TABLE <tablename> (<column definition> [<constraint definition>])

In addition, a SET command specifies the file and the separator character that the Text table uses:

    SET TABLE <tablename> SOURCE <quoted_filename_and_options> [DESC]

Text Tables cannot be created in memory-only databases (databases that have no script file).

This has changed since 1.7.2 to support both null values and empty strings.

The default field separator is a comma (,). A different field separator can be specified within the SET TABLE SOURCE statement. For example, to change the field separator for the table mytable to a vertical bar, place the following in the SET TABLE SOURCE statement, for example:

    SET TABLE mytable SOURCE "myfile;fs=|"

Since HSQLDB treats CHAR's, VARCHARs, and LONGVARCHARs the same, the ability to assign different separators to the latter two is provided. When a different separator is assigned to a VARCHAR or LONGVARCHAR field, it will terminate any CSV field of that type. For example, if the first field is CHAR, and the second field LONGVARCHAR, and the separator fs has been defined as the pipe (|) and vs as the period (.) then the data in the CSV file for a row will look like:

    First field data|Second field data.Third field data

The following example shows how to change the default separator to the pipe (|), VARCHAR separator to the period (.) and the LONGVARCHAR separator to the tilde (~). Place the following within the SET TABLE SOURCE statement, for example:

    SET TABLE mytable SOURCE "myfile;fs=|;vs=.;lvs=~"

HSQLDB also recognises the following special indicators for separators:

Furthermore, HSQLDB provides csv file support with three additional boolean options: ignore_first, quoted and all_quoted. The ignore_first option (default false) tells HSQLDB to ignore the first line in a file. This option is used when the first line of the file contains column headings. The all_quoted option (default false) tells the program that it should use quotes around all character fields when writing to the source file. The quoted option (default true) uses quotes only when necessary to distinguish a field that contains the separator character. It can be set to false to prevent the use of quoting altogether and treat quote characters as normal characters. These options may be specified within the SET TABLE SOURCE statement:

    SET TABLE mytable SOURCE "myfile;ignore_first=true;all_quoted=true"

When the default options all_quoted= false and quoted=true are in force, fields that are written to a line of the csv file will be quoted only if they contain the separator or the quote character. The quote character is doubled when used inside a string. When all_quoted=false and quoted=false the quote character is not doubled. With this option, it is not possible to insert any string containing the separator into the table, as it would become impossible to distinguish from a separator. While reading an existing data source file, the program treats each individual field separately. It determines that a field is quoted only if the first character is the quote character. It interprets the rest of the field on this basis.

The character encoding for the source file is ASCII by default. To support UNICODE or source files preprared with different encodings this can be changed to UTF-8 or any other encoding. The default is encoding=ASCII and the option encoding=UTF-8 or other supported encodings can be used.

Finally, HSQLDB provides the ability to read a text file from the bottom up and making them READ ONLY, by placing the keyword "DESC" at the end of the SET TABLE SOURCE statement:

    SET TABLE mytable SOURCE "myfile" DESC

This feature provides functionality similar to the Unix tail command, by re-reading the file each time a select is executed. Using this feature sets the table to read-only mode. Afterwards, it will no longer be possible to change the read-only status with SET TABLE <tablename> READONLY TRUE.

Text table source files are cached in memory. The maximum number of rows of data that are in memory at any time is controlled by the textdb.cache_scale property. The default value for textdb.cache_scale is 10 and can be changed by setting the property in the .properties file for the database. The number of rows in memory is calculated as 3*(2**scale), which translates to 3072 rows for the default textdb.cache_scale setting (10). The property can also be set for individual text tables:

    SET TABLE mytable SOURCE "myfile;ignore_first=true;all_quoted=true;cache_scale=12"

The following describes behaviour present in 1.8.0.8 and later.

Text tables may be disconnected from their underlying data source, i.e. the text file.

You can explicitly disconnect a text table from its file by issuing the following statement:

  SET TABLE mytable SOURCE OFF

Subsequently, mytable will be empty and read-only. However, the data source description will be preserved, and the table can be re-connected to it with

  SET TABLE mytable SOURCE ON

When a database is opened, if the source file for an existing text table is missing the table remains disconnected from its data source, but the source sescription is preserved. This allows the missing source file to be added to the directory and the table re-connected to it with the above command.