InterSystems Caché ODBC - max result length

Question

I use ODBC for querying on InterSystems Caché db.

In C# I do:

DbCommand.CommandText = "select Class_getTablesMetaXml('globalName') As returnStr";
OdbcDataReader reader = DbCommand.ExecuteReader();

Everything is OK, but if returnStr is longer than 16374 characters returnStr seems to be empty in C#.

According doc (http://docs.intersystems.com/ens20082/csp/docbook/DocBook.UI.Page.cls?KEY=RSQL_datatype#RSQL_datatype_longstrings) I should use CStream%String datatype, but I don't know how to achieve it.

My caché procedure method looks like:

ClassMethod getTablesMetaXml(globalName As %String) As %String [ SqlProc ]
{
    set global = "^"_globalName

    set xmlString = "<global><name>"_globalName_"</name>"

    set tableCount = 0
    set iTab = ""
    for
    {
        set tableCount = tableCount+1
        set iTab = $order( @global@("tab", iTab) )
        quit:(iTab = "")

        set xmlString = xmlString _ "<table>"
        set xmlString = xmlString _     "<title>"_@global@("tab", iTab, "Name")_"</title>"
        set xmlString = xmlString _     "<indexTab>"_iTab_"</indexTab>"

        set i=""
        set propCount = 0
        for
        {
            set propCount = propCount + 1
            set i = $order( @global@("tab",iTab,"sMeta", i) )
            quit:(i = "")

            set xmlString = xmlString _ "<col>"
            set xmlString = xmlString _     "<title>" _ ..zcvXml(@global@("tab",iTab,"sMeta",i)) _ "</title>"
            set xmlString = xmlString _     "<name>prop" _ propCount _ "</name>"
            set xmlString = xmlString _     "<format>" _ ..zcvXml($g(@global@("tab",iTab,"sMeta",i,"Format"))) _ "</format>"
            set xmlString = xmlString _ "</col>"
        }
    set xmlString = xmlString _ "</table>"
    }

    set xmlString = xmlString _ "</global>"

    q xmlString
}

My Caché version is: 2009.1.3 (Build 704U)

In configuration I have checked: Enable Long Strings

After query "select Class_getTablesMetaXml('globalName') As returnStr", I get XML string. But if its longer than 16374, I get empty string in my C# app where I use ODBC for querying. I need solve it or do something like get string of 15000 length and then second string which I will concatenate in my app(c#), but i absolutely don't know how to do it.

Answer 1

To use CStream%String you should change return type from %String to %GlobalCharacterStream in your SqlProc and change your code because it is Stream. And for generating XML, try to use %XML.Writer