Tableau data types are classified into one of the four categories namely – String, Number, Boolean and datetime. Once data is loaded from source, tableau automatically assigns the data types, but you can also change some of the data types if it satisfies the data conversion rule. Also the user has to specify the data type for calculated fields.
Tableau data types
1. STRING Tableau data types– Any sequence of zero or more characters. They are enclosed within single quotes. The quote itself can be included in a string by writing it twice. ‘Hello’
‘Quoted’ ‘quote’. They are further divided into – char and varchar2
- Char data type- It is used when fixed length character string is required. The largest size of char data type is 2000 bytes.It can store alphanumeric values. Data should enter in single quotes. Note:- If the user enters a value shorter than the specified length then the database adds blank-pads to the fixed length. In case, if the user enters a value larger than the specified length then the database would return an error.
- Varchar2 data type- It stores alphanumeric values and supports a variable length character string. The largest size of char data type is 4000 bytes and occupies only that space for which the data is supplied. Data should enter in single quotes. Note:- Using varchar2 saves disk space when compared to char. Database would return an error, if the user enters a value larger than the specified length.
2. NUMBER Tableau data types- These are either integers (zero, positive and negative fixed) or floating points. It is advised to round the floating point numbers while using them in calculations. The general declaration is- Number (P, S) where, P- It specifies the precision, i.e. the total number of digits (1 to 38) and, S- It specifies the scale, i.e. the number of digits to the right of the decimal point, can range from -84 to 127.
3. BOOLEAN Tableau data types- They are logical values- TRUE and FALSE.
4. DATE & DATETIME Tableau data types- It is used to store DATE and TIME information.
- DATE data type- Default date format is “dd-mon-yy” or “dd-mon-yyyy”. Tableau recognizes dates in almost all formats. Eg– “02/01/2015”. But, if we need to force tableau to recognize a string as date then we have to put a # sign before the data like-“#3 March 1982”. It allocates fixed length of 7 bytes each for century, year, month, day, hour, minute and second. The date range provided by oracle is January 1, 4712 BC to December 31, 4712 AD.
- Timestamp data type- It is an extension of the DATE data type. It stores the data in the form of century, year, month, date, hour, minute and second.
5. LONG Tableau data types- This data type stores variable length character strings. It is used to store very lengthy text strings. The largest size is 2 GB. The length of long values may be limited by the memory available on the computer. Note:- A single table can contain only one long column. Objects types cannot be created on long column Attribute. Long columns cannot appear in where clauses or in Integrity constraints. Indexes cannot be created on long columns. Long can be Returned through a function, but not through a stored procedure. Stored procedures cannot accept long data as arguments. It can be declared in a PL/SQL unit but cannot be referenced in SQL.
6. Raw Tableau data types- It is used to store binary data like photos, signatures, thumb impressions etc. The largest size is 2000 bytes. While using this data type the size should be mentioned because by default it does not specify any size. Only storage and retrieval of data are possible, manipulations of data cannot be done. This data type can be indexed.
- Long Raw data type- It is also used to store binary data. The largest size is 2 GB. This data type cannot be indexed.
7. Large Object (LOB) Tableau data types- The built in LOB data types are: BLOB, CLOB and BFILE. BLOB and CLOB stores data internally. The BFILE is LOB which stores the data externally. The LOB data type can store large and unstructured data like text, image, audio and video. The Maximum storage size is up to 4 GB. BLOB stores unstructured binary large objects. CLOB stores single byte and multi byte character data.
This puts an end to the classification of Tableau data types.