Question

I’m inserting many rows in a table having the following schema:

TABLE "SPACE"."WORKTABLE" 
   (    "ID" NUMBER, 
    "AUTHOR" VARCHAR2(20 BYTE), 
    "INSERTION_DATE" DATE, 
    "XML_DOCUMENT" "SYS"."XMLTYPE" 
   )

The insertion is being done using ADO.NET (OracleXmlType).
The first inserted row takes more than two minutes to finish; but after this insertion is done, all the following take much less time than the first one.

1. Why is this so?
2. Is this only related to the XML parsing being done when inserting the XML? Why (if yes) it happens only at the first insertion?
3. Can this time be reduced?

(please, if possible, document your answers)

UPDATE:
The code being executed is a simple insertion for at most 10 rows having an XML of 5500 character length. Also, I’ve already taken away the time taken to the connection to be opened as a cause of the lag.

string sql = "INSERT INTO WORKTABLE VALUES ( " + rowID + ",'JBALVIN',1,'01-JAN-12',:xmldocument)";
using (OracleCommand comm = new OracleCommand(sql, con))
{
    comm.Parameters.Add(":xmldocument", OracleDbType.XmlType);
    OracleXmlType xmlType = new OracleXmlType(con, entidadXML);
    comm.Parameters[0].Value = xmlType;
    comm.ExecuteNonQuery();
}

UPDATE:

We have noticed that the line causing the delay is OracleXmlType xmlType = new OracleXmlType(con, entidadXML);. Could it be fixed by stopping Oracle to check XML validity? If so… how can it be done? by a direct command using the connection?

Answer 1

Hmmm… after some guessing and googling, I found that if the URLs with the schema used on the XML are deleted (attributes xmlns:xsi and xsi:noNamespaceSchemaLocation), the insertion is done in the order of milliseconds. Sadly, this behavior is not documented at Oracle OracleXmlType documentation.