[teiid-issues] [JBoss JIRA] (TEIID-5965) Allow variables to be used as TextTable delimeters, row delimeters, quote, header, skip rows, and escape characters

[Dmitrii Pogorelov (Jira)]

Dmitrii Pogorelov created TEIID-5965:
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             Summary: Allow variables to be used as TextTable delimeters, row delimeters, quote, header, skip rows, and escape characters
                 Key: TEIID-5965
                 URL: https://issues.redhat.com/browse/TEIID-5965
             Project: Teiid
          Issue Type: Enhancement
          Components: Query Engine
    Affects Versions: 13.1
            Reporter: Dmitrii Pogorelov
            Assignee: Steven Hawkins


In the specified example, the delimiter is TAB. Many web APIs allow customization of the delimiter character, and in order to provide a generic parser, sometimes it is way easier to define a delimiter as a variable, and not need to create a long nested structure with IF-THEN-ELSE-IF-ELSE constructs:
{code:sql}
Select * From TextTable (
	'c1	c2
1	2'
	Columns
		c1 integer,
		c2 integer
	Delimiter E'\t'
	Header 1
)x;
{code}
Imagine that based on setup on API side (out of our control) the content can be delivered via tab or semicolon, e.g.
{code}
c1;c2
1;2
{code}
or
{code}
c1	c2
1	2
{code}

Let's save this response into a variable and see the code, which we will need to write depending on the setup:
{code:sql}
Begin
    ...
    If (delimiter = 'tab')
    Begin
        Select * From TextTable (
            apiResponse
            Columns
                c1 integer,
                c2 integer
            Delimiter E'\t'
            Header 1
        )x;
    End
    Else If (delimiter = 'tab')
    Begin
        Select * From TextTable (
            apiResponse
            Columns
                c1 integer,
                c2 integer
            Delimiter ';'
            Header 1
        )x;
    End
End
{code}

The if-else block is constantly growing, especially if we want to customize quote, escape, delimiter, and row delimiter.
Thus it would be great if we could make these values configurable. In this case, we could end up with this expected code, which is more readable and more easily customizable:
{code:sql}
Begin
    ...
    Declare string delimiter = E'\t';
    Select * From TextTable (
        apiResponse
        Columns
            c1 integer,
            c2 integer
        Delimiter delimiter
        Header 1
    )x;
End
{code}

With a bit of tweaking and certain assumptions, leading in the trust level, we can even read the first line and try to auto-detect the delimiter automatically (e.g. by counting tabs, commas, and semicolons in the first line).

Please, could you be so kind as to make HEADER and SKIP values customizable (rather than hardcoded numbers)?



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