Hello Richard1989,
The field tags you see under Document properties ~> Tables are descriptive only, and do not represent the "official" data-typing when encapsulated in QVD.
There is XML metadata in the front of each QVD, and the <type> tag indicates how each field was QVD encapsulated: REAL, INTEGER, ASCII, & UNKNOWN.
Notice the resultant QVD metadata when running this sample script, even though some of these fields only load 1 integer, 1 float, or 1 text, the QVD still types the fields UNKNOWN. This is not a mistake, but rather Qlik fields do not like to limit their options by "painting themselves into a data type corner". These fields can still be appended with any other type of data, in any mixture, this data type flexibility is one of the major conveniences of the platform.
One way to "cast" the data <type> is using the Floor(), Num(#.#), or Text() functions around the first entry that is entered into the field. You'll notice in these cases the QVD commits to REAL, INTEGER, ASCII. And in some cases when you attempt to append non-numeric data to a "committed numeric" data type, you'll see strange kind of errors observable in other software, things like values showing up with '?' symbols. (meaning Qlik is unable to assign a numeric value to the entry)
I hadn't realized Parquet wasn't able to accept blended fields, but once you get used to not having to explicitly cast data types (at least during load scripts), you never want to go back. (naturally data typing still comes into play when using functions designed for a specific type of data).
[TYPES]:
LOAD
Floor(1) AS Integer_w_Num_Function, //this produces QVD type INTEGER
Num(1.) As Real, //this produces QVD type REAL
Text('Text') As Text_Only, //this produces ASCII type
1 AS Integer, //this and the rest all produce type UNKNOWN
'ஸ' AS UNICODE, //Unicode comes up as UNKNOWN
1.1 AS Float,
1 AS Mixed_Int_Float,
'Text' AS AlphaNumeric_Text_Loads_First,
1 AS AlphaNumeric_Num_Loads_First AUTOGENERATE(1);
CONCATENATE(TYPES) LOAD
1.1 AS Mixed_Int_Float,
1 as AlphaNumeric,
'Text' AS AlphaNumeric_Num_Loads_First AUTOGENERATE(1);
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<QvdTableHeader>
<CreatorDoc>datatypes.qvw</CreatorDoc>
<CreateUtcTime>2020-03-14 01:15:30</CreateUtcTime>
<TableName>TYPES</TableName>
<Fields>
<QvdFieldHeader>
<FieldName>Integer_w_Num_Function</FieldName>
<BitOffset>0</BitOffset>
<BitWidth>8</BitWidth>
<Bias>-2</Bias>
<NumberFormat>
<Type>INTEGER</Type>
<nDec>0</nDec>
<UseThou>1</UseThou>
<Fmt>###0</Fmt>
<Dec>.</Dec>
<Thou></Thou>
</NumberFormat>
<NoOfSymbols>1</NoOfSymbols>
<Offset>0</Offset>
<Length>5</Length>
<Comment></Comment>
<Tags>
<String>$numeric</String>
<String>$integer</String>
</Tags>
</QvdFieldHeader>
<QvdFieldHeader>
<FieldName>Real</FieldName>
<BitOffset>8</BitOffset>
<BitWidth>2</BitWidth>
<Bias>-2</Bias>
<NumberFormat>
<Type>REAL</Type>
<nDec>14</nDec>
<UseThou>1</UseThou>
<Fmt>##############</Fmt>
<Dec>.</Dec>
<Thou></Thou>
</NumberFormat>
<NoOfSymbols>1</NoOfSymbols>
<Offset>5</Offset>
<Length>7</Length>
<Comment></Comment>
<Tags>
<String>$numeric</String>
<String>$integer</String>
</Tags>
</QvdFieldHeader>
<QvdFieldHeader>
<FieldName>Text_Only</FieldName>
<BitOffset>10</BitOffset>
<BitWidth>2</BitWidth>
<Bias>-2</Bias>
<NumberFormat>
<Type>ASCII</Type>
<nDec>0</nDec>
<UseThou>0</UseThou>
<Fmt></Fmt>
<Dec></Dec>
<Thou></Thou>
</NumberFormat>
<NoOfSymbols>1</NoOfSymbols>
<Offset>12</Offset>
<Length>6</Length>
<Comment></Comment>
<Tags>
<String>$ascii</String>
<String>$text</String>
</Tags>
</QvdFieldHeader>
<QvdFieldHeader>
<FieldName>Integer</FieldName>
<BitOffset>12</BitOffset>
<BitWidth>2</BitWidth>
<Bias>-2</Bias>
<NumberFormat>
<Type>UNKNOWN</Type>
<nDec>0</nDec>
<UseThou>0</UseThou>
<Fmt></Fmt>
<Dec></Dec>
<Thou></Thou>
</NumberFormat>
<NoOfSymbols>1</NoOfSymbols>
<Offset>18</Offset>
<Length>7</Length>
<Comment></Comment>
<Tags>
<String>$numeric</String>
<String>$integer</String>
</Tags>
</QvdFieldHeader>
<QvdFieldHeader>
<FieldName>UNICODE</FieldName>
<BitOffset>14</BitOffset>
<BitWidth>2</BitWidth>
<Bias>-2</Bias>
<NumberFormat>
<Type>UNKNOWN</Type>
<nDec>0</nDec>
<UseThou>0</UseThou>
<Fmt></Fmt>
<Dec></Dec>
<Thou></Thou>
</NumberFormat>
<NoOfSymbols>1</NoOfSymbols>
<Offset>25</Offset>
<Length>5</Length>
<Comment></Comment>
<Tags>
<String>$text</String>
</Tags>
</QvdFieldHeader>
<QvdFieldHeader>
<FieldName>Float</FieldName>
<BitOffset>16</BitOffset>
<BitWidth>2</BitWidth>
<Bias>-2</Bias>
<NumberFormat>
<Type>UNKNOWN</Type>
<nDec>0</nDec>
<UseThou>0</UseThou>
<Fmt></Fmt>
<Dec></Dec>
<Thou></Thou>
</NumberFormat>
<NoOfSymbols>1</NoOfSymbols>
<Offset>30</Offset>
<Length>13</Length>
<Comment></Comment>
<Tags>
STORE * FROM TYPES INTO TYPES.QVD (QVD);
