Deadlock when delete rows with blob.

Question

Hello
I have the following issue. I try to clean a table that contains a BLOB column.
To do this I use SQLDBC I create a statement that contains the LOB column, I fetch the line, load the Blob. and before fetching the next line, I send a delete request. and I fall in the deadlock.
If I fetch the next line before sending the delete request there is no deadlock, there is also no deadlock if i do not request le LOB column in the select.
In fact when I made select with LOB, there is the follwing line in DOMAIN.LOCKS
SESSION;TRANSCOUNT;PROCESS;USERNAME;DATE;TIME;TERMID;LASTWRITE;LOCKMODE;LOCKSTATE;APPLPROCESS;APPLNODE;SCHEMANAME;OWNER;TABLENAME;TABLEID;ROWIDLENGTH;ROWIDHEX;ROWID;
295513;                4290;438;ESKDBADM;2010-06-17;12:05:46;ly-delorme-u..1674;?;tab_share;?;5748;LY-DELORME.esker.corp;?;?;?;0000800000046919;0;?;?
when i send the delete request the following lock appears in DOMAIN.LOCKS. A exclusif lock on the column I want to delete. It's ok
SESSION;TRANSCOUNT;PROCESS;USERNAME;DATE;TIME;TERMID;LASTWRITE;LOCKMODE;LOCKSTATE;APPLPROCESS;APPLNODE;SCHEMANAME;OWNER;TABLENAME;TABLEID;ROWIDLENGTH;ROWIDHEX;ROWID;
295521;                4287;167;ESKDBADM;2010-06-17;12:05:49;ly-delorme-u..1674;         5;row_exclusive;write;5748;LY-DELORME.esker.corp;ESKDBADM;ESKDBADM;DBM350_AUTOTESTXML;0000000000000934;5;00C51133800000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000;
BUT there is a dead lock , I think because of the following entry in DOMAIN.LOCK_WAITS
TABLENAME;TABLEID;H_TERMID;H_PROCESS;H_APPLPROCESS;H_APPLNODE;H_ROWIDHEX;H_ROWID;H_LOCKMODE;H_DATE;H_TIME;H_LOCKTIMEOUT;R_TERMID;R_PROCESS;R_APPLPROCESS;R_APPLNODE;R_ROWIDHEX;R_ROWID;R_REQMODE;R_DATE;R_TIME;R_REQTIMEOUT;
?;0000800000046919;ly-delorme-u..1674;438;5748;LY-DELORME.esker.corp;?;?;tab_share;2010-06-17;12:05:46;?;ly-delorme-u..1674;167;5748;LY-DELORME.esker.corp;?;?;tab_exclusive;2010-06-17;12:05:49;      3585
The database request a tab_exclusive lock on tableid 0000800000046918 but there is already a tab_share lock on this.
Do you why there is a lock on the table :  tableid 0000800000046918 ?
How to avoid this lock using SQLDBC ?
Thanks for you help.
Yann.

Answer 1

this is the same reply as previous reply, this carriage return. I hope.
Hello,
Here is code that explain my issue.
I create a table like this :
create table "ESKDBADM"."DBM350_AUTOTESTXML"( "MSN" INTEGER not null, "DIST_FILE" BLOB, constraint SYSPRIMARYKEY primary key ("MSN"))
And then I try to delete row with the following program. I do not understand why the request SELECT Msn, DIST_FILE FROM DBM350_AUTOTESTXML set a share lock on the tableid : 000080000004691D.
I do not find this tableid in the "SYSINFO"."FILES" table.
SESSION;TRANSCOUNT;PROCESS;USERNAME;DATE;TIME;TERMID;LASTWRITE;LOCKMODE;LOCKSTATE;APPLPROCESS;APPLNODE;SCHEMANAME;OWNER;TABLENAME;TABLEID;ROWIDLENGTH;ROWIDHEX;ROWID;
295697; 5220;172;ESKDBADM;2010-06-21;11:01:40;ly-delorme-u..1CDC;?;tab_share;?;7388;LY-DELORME.esker.corp;?;?;?;000080000004691D;0;?;?
// SQLDBC.cpp : Defines the entry point for the console application.
// YOU MUST CHANGE CONNECTION SETTINGS.
#include "stdafx.h"
#include <stdio.h>
#include <tchar.h>
#include <comdef.h>
#include <iostream>
#include "SQLDBC.h"
using namespace SQLDBC;
static void parseArgs(int argc, wchar_t **argv);
static SQLDBC_Connection *connectDB(SQLDBC_Environment * env = NULL);
static char* convertToUCS2(char *src);
static void usage();
SQLDBC_Environment *g_env;
typedef struct ConnectArgsT {
  bstrt username;
  bstrt password;
  bstrt dbname;  
  bstrt host;    
  bstrt request;    
} ConnectArgsT;
ConnectArgsT connectArgs;
void exitOnError(SQLDBC_ErrorHndl &err);
int _tmain(int argc, _TCHAR* argv[])
   parseArgs(argc, argv);
   SQLDBC_Connection *conn = connectDB();
   //* Create a new statment object and execute it.
   SQLDBC_PreparedStatement *stmt = conn->createPreparedStatement();
   // FREEZE
   if (connectArgs.request.length() == 0)
           connectArgs.request = "SELECT Msn, DIST_FILE FROM DBM350_AUTOTESTXML";     
   /* NO FREEZE
   if (connectArgs.request.length() == 0)
           connectArgs.request = "SELECT Msn FROM DBM350_AUTOTESTXML";
   char command = (char)((LPCWSTR)(connectArgs.request));
    //* Executes the UNICODE encoded SQL command.
   SQLDBC_Retcode ret = stmt->prepare((const char*)command, SQLDBC_StringEncodingType::UCS2Swapped);
   exitOnError(stmt->error());
   stmt->execute();
   exitOnError(stmt->error());
   // * Get the resultset.  
   SQLDBC_ResultSet *result;
   result = stmt->getResultSet();
   exitOnError(stmt->error());
   // * Fetch the row from the resultset.     
   result->next();
        SQLDBC::SQLDBC_RowSet* pRowset =  result->getRowSet();
     ret = pRowset->fetch();          
   exitOnError(result->error());
   wchar_t szString[30];
   SQLDBC_Length ind;
Get a string value from the column.
   result->getObject(1, SQLDBC_HOSTTYPE_UCS2_SWAPPED, szString, &ind, sizeof(szString)); // Retreive MSN.
   // Delete de line.
   // Create a new connection for delete
   SQLDBC_Connection *conn2 = connectDB(g_env);
   //* Create a new statment object and execute it.
   SQLDBC_PreparedStatement *stmt2 = conn2->createPreparedStatement();
     std::wstring st = L"DELETE FROM DBM350_AUTOTESTXML WHERE MSN=";
     st +=  szString;
     stmt2->prepare((char*)st.c_str(), SQLDBC_StringEncodingType::UCS2Swapped);
    //* Executes the UNICODE encoded SQL command.
     ret = stmt2->execute();
   exitOnError(stmt->error());
   printf("%s\n", szString);
   return 0;
static char *convertToUCS2(char *src)
  int len = strlen(src);
  wchar_t w=(wchar_t)calloc(len, sizeof(wchar_t));
  int nc = mbstowcs(w, src, len);
  if ((size_t)-1 == nc) {
    fprintf(stderr, "Conversion to UCS2 failed. Execution stopped.\n");
    exit(1);
  short s=(SQLDBC_Int2)calloc(nc+1, sizeof(SQLDBC_Int2));
  int i;
  for(i=0; i<nc; i++) {
    s<i> = w<i>;
  free(w);
  return (char*)s;
static char* strupper(char *str)
    char *p=str;
    while(*p) {
        p=toupper(p);
        ++p;
    return str;
static wchar_t *argv0;      
#ifdef WIN32
#define STRICMP _stricmp
#else
#define STRICMP strcasecmp
#endif
SQLDBC_Connection *connectDB(SQLDBC_Environment * env)
  char errorText[200];
  SQLDBC_Retcode rc;
  if (g_env == NULL)
Every application has to initialize the SQLDBC library by getting a
reference to the ClientRuntime and calling the SQLDBC_Environment constructor.
       SQLDBC_IRuntime *runtime;
       runtime = SQLDBC::GetClientRuntime(errorText, sizeof(errorText));
       if (!runtime) {
          fprintf(stderr, "Getting instance of the ClientRuntime failed %s\n", errorText);
          usage();
       env = new SQLDBC_Environment(runtime);
       g_env = env;
Create a new connection object and open a session to the database.
  SQLDBC_Connection *conn = env->createConnection();
  printf("Connecting to '%s' on '%s' as user '%s'\n",
         (char)connectArgs.dbname, (char)connectArgs.host, (char*)connectArgs.username);
  rc = conn->connect(connectArgs.host, connectArgs.dbname,
                     connectArgs.username, connectArgs.password);
  if(SQLDBC_OK != rc) {
    fprintf(stderr, "Can't connect to '%s'.\nERROR: %d:'%s'\n",
            connectArgs.dbname, conn->error().getErrorCode(), conn->error().getErrorText());
    exit(1);
  return conn;
static void parseArgs (int argc, wchar_t **argv)
  argv0 = wcsdup(argv[0]);
setting defaults for demo database
  connectArgs.username = "ESKDBADM";
  connectArgs.password = "DELORME";
  connectArgs.dbname = "EDP350";
  connectArgs.host = "ly-delorme";
use values from command line
  if (argc > 5) {
    connectArgs.request = argv [5];
  if (argc > 4) {
    connectArgs.host = argv [4];
  if (argc > 3) {
    connectArgs.dbname = argv [3];
  if (argc > 2) {
    connectArgs.password = argv [2];
  if (argc > 1) {
    if (!wcsicmp(argv [1], L"-h"))
      usage();
    else {
      connectArgs.username = argv [1];
  strupper(connectArgs.username);
  strupper(connectArgs.password);
void exitOnError(SQLDBC_ErrorHndl &err)
  if(err) {
    fprintf(stderr, "Execution stopped %d:'%s'", err.getErrorCode(), err.getErrorText());
    exit(1);
static void usage()
  wchar_t *s = wcsrchr(argv0, L'/');
  if (!s)
    s = wcsrchr(argv0, L'
  if (s)
    *s = '\0';
  printf("Syntax: %s [-h] | [<connect_options>]\n"
         "\tconnect_options :: \n"
         "\t\t[ <username> \n"
         "\t\t[ <password>\n"
         "\t\t[ <database_name>\n"
         "\t\t[ <database_server> ]]]]\n"
           "\t\t[ <request> ]]]]\n"
         "\tCalling %s without any arguments will use user '%s','%s'\n"
         "\t\ton database '%s' at server '%s'\n",
         argv0, argv0,
         connectArgs.username, connectArgs.password,
         connectArgs.dbname, connectArgs.host);
  exit(1);