OTL 4.0, Example 113 (OTL stream pooling, Oracle 7/8/8i)

Example 113 (OTL stream pooling, Oracle 7/8/8i)

This example demonstrates the OTL stream pooling for Oracle 8/8i. The same example can be used with Oracle 7, if #define OTL_ORA7 is used instead of #define OTL_ORA8 (OTL_ORA8I).

Source Code

#include <iostream>
using namespace std;

#include <stdio.h>
// Uncomment the line below when OCI7 is used with OTL
// #define OTL_ORA7 // Compile OTL 4.0/OCI7
#define OTL_ORA8 // Compile OTL 4.0/OCI8
#define OTL_STL // turn on OTL in the STL compliance mode
#define OTL_STREAM_POOLING_ON 
 // turn on OTL stream pooling.
 // #define OTL_STREAM_POOLING_ON line 
 // can be commented out the number of iterations in
 // the select() loop can be increased, and the difference 
 // in performace with and without OTL_STREAM_POOLING_ON can
 // be benchmarked. The difference should grow with the overall
 // number of streams to be used in one program.

#define OTL_STREAM_POOL_USES_STREAM_LABEL_AS_KEY

#include <otlv4.h> // include the OTL 4.0 header file

otl_connect db; // connect object

void insert()
// insert rows into table

 otl_stream o(50, // buffer size
              "insert into test_tab values(:f1<int>,:f2<char[31]>)", 
                 // SQL statement
              db // connect object
             );
 char tmp[32];

 for(int i=1;i<=100;++i){
  sprintf(tmp,"Name%d",i);
  o<<i<<tmp;
 }
#ifdef OTL_STREAM_POOLING_ON
 o.close(false); // do not save the stream in the stream pool.
                 // in other words, destroy it on the spot, since
                 // the stream is not going to be reused later.
#else
 o.close();
#endif
}

void select()
{ // when this function is called in a loop,
  // on the second iteration of the loop the streams i1, i2 will
  // will get the instances of the OTL stream from the stream
  // pool, "fast reopen", so to speak.

 otl_stream i1(50, // buffer size
               "select * from test_tab where f1>=:f11<int> and f1<=:f12<int>*2",
                 // SELECT statement
              db // connect object
0, // ref.cur. name
"SEL01" // sql stream label
             ); 
   // create select stream
 
 otl_stream i2(33, // buffer size
               "select f1,f2 from test_tab where f1>=:f11<int> and f1<=:f12<int>*2",
                 // SELECT statement
              db // connect object
             ); 
   // create select stream

// i1 and i2 are NOT similar, because their buffer sizes as well
// as SQL statements are not equal. It will generate two entry points in the
// OTL stream pool.
 
 int f1;
 char f2[31];

 i1<<2<<2; // assigning :f11 = 2, :f12 = 2
   // SELECT automatically executes when all input variables are
   // assigned. First portion of output rows is fetched to the buffer

 while(!i1.eof()){ // while not end-of-data
  i1>>f1>>f2;
  cout<<"I1==> f1="<<f1<<", f2="<<f2<<endl;
 }

 i2<<3<<3; // assigning :f11 = 2, :f12 = 2
   // SELECT automatically executes when all input variables are
   // assigned. First portion of output rows is fetched to the buffer

 while(!i2.eof()){ // while not end-of-data
  i2>>f1>>f2;
  cout<<"I2==> f1="<<f1<<", f2="<<f2<<endl;
 }

} // destructors of i1, i2 will call the close()
  // function for both of the streams and the OTL stream
  // instances will be placed in the stream pool.

int main()
{
 otl_connect::otl_initialize(); // initialize the environment
 try{

  db.rlogon("scott/tiger"); // connect to the database
#ifdef OTL_STREAM_POOLING_ON
  db.set_stream_pool_size(2); 
   // set the maximum stream pool size and actually initializes 
   // the stream pool.
   // if this function is not called, the stream pool
   // gets initialized anyway, with the default size of 32 entries.
#endif

  otl_cursor::direct_exec
   (
    db,
    "drop table test_tab",
    otl_exception::disabled // disable OTL exceptions
   ); // drop table

  otl_cursor::direct_exec
   (
    db,
    "create table test_tab(f1 int, f2 varchar(30))"
    );  // create table

  insert(); // insert records into table
  for(int i=1;i<=10; ++i){
    cout<<"===================> Iteration: "<<i<<endl;
    select(); // select records from table
  }
 }

 catch(otl_exception& p){ // intercept OTL exceptions
  cerr<<p.msg<<endl; // print out error message
  cerr<<p.stm_text<<endl; // print out SQL that caused the error
  cerr<<p.var_info<<endl; // print out the variable that caused the error
 }

 db.logoff(); // disconnect from the database

 return 0;

}

Output

===================> Iteration: 1
I1==> f1=2, f2=Name2
I1==> f1=3, f2=Name3
I1==> f1=4, f2=Name4
I2==> f1=3, f2=Name3
I2==> f1=4, f2=Name4
I2==> f1=5, f2=Name5
I2==> f1=6, f2=Name6
===================> Iteration: 2
I1==> f1=2, f2=Name2
I1==> f1=3, f2=Name3
I1==> f1=4, f2=Name4
I2==> f1=3, f2=Name3
I2==> f1=4, f2=Name4
I2==> f1=5, f2=Name5
I2==> f1=6, f2=Name6
===================> Iteration: 3
I1==> f1=2, f2=Name2
I1==> f1=3, f2=Name3
I1==> f1=4, f2=Name4
I2==> f1=3, f2=Name3
I2==> f1=4, f2=Name4
I2==> f1=5, f2=Name5
I2==> f1=6, f2=Name6
===================> Iteration: 4
I1==> f1=2, f2=Name2
I1==> f1=3, f2=Name3
I1==> f1=4, f2=Name4
I2==> f1=3, f2=Name3
I2==> f1=4, f2=Name4
I2==> f1=5, f2=Name5
I2==> f1=6, f2=Name6
===================> Iteration: 5
I1==> f1=2, f2=Name2
I1==> f1=3, f2=Name3
I1==> f1=4, f2=Name4
I2==> f1=3, f2=Name3
I2==> f1=4, f2=Name4
I2==> f1=5, f2=Name5
I2==> f1=6, f2=Name6
===================> Iteration: 6
I1==> f1=2, f2=Name2
I1==> f1=3, f2=Name3
I1==> f1=4, f2=Name4
I2==> f1=3, f2=Name3
I2==> f1=4, f2=Name4
I2==> f1=5, f2=Name5
I2==> f1=6, f2=Name6
===================> Iteration: 7
I1==> f1=2, f2=Name2
I1==> f1=3, f2=Name3
I1==> f1=4, f2=Name4
I2==> f1=3, f2=Name3
I2==> f1=4, f2=Name4
I2==> f1=5, f2=Name5
I2==> f1=6, f2=Name6
===================> Iteration: 8
I1==> f1=2, f2=Name2
I1==> f1=3, f2=Name3
I1==> f1=4, f2=Name4
I2==> f1=3, f2=Name3
I2==> f1=4, f2=Name4
I2==> f1=5, f2=Name5
I2==> f1=6, f2=Name6
===================> Iteration: 9
I1==> f1=2, f2=Name2
I1==> f1=3, f2=Name3
I1==> f1=4, f2=Name4
I2==> f1=3, f2=Name3
I2==> f1=4, f2=Name4
I2==> f1=5, f2=Name5
I2==> f1=6, f2=Name6
===================> Iteration: 10
I1==> f1=2, f2=Name2
I1==> f1=3, f2=Name3
I1==> f1=4, f2=Name4
I2==> f1=3, f2=Name3
I2==> f1=4, f2=Name4
I2==> f1=5, f2=Name5
I2==> f1=6, f2=Name6










Examples ContentsGo
Home

Copyright © 1996-2017, Sergei Kuchin, email: skuchin@gmail.com,
skuchin@gmail.com .

Permission to use, copy, modify and redistribute this document
for
any purpose is hereby granted without fee, provided that the above
copyright
notice appear in all copies. THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.