Blob type returned ?

[lexicalunit]

From @renzo38 on December 8, 2014 11:48

Hello,

First of all, thanks for this really great wrapper. I am encountering a problem while using nanodbc on the following platform:

• Fedora Core 20
• sqlite-3.8.7
• sqliteodbc-0.999
• unixODBC-2.3.2-4
• latest nanodbc release

I open a minimalist sqlite db containing only one table created as follow:

CREATE TABLE "PIPES" ("Name" TEXT);

Then, trying to execute the request:

SELECT name FROM sqlite_master WHERE type='table';

leads to a runtime_error with "blob not implemented yet" as the error message. Is this a bug or not ?

Thanks.

Copied from original issue: lexicalunit/nanodbc#32

[lexicalunit]

I never implemented proper handling of the BLOB types because it was never necessary for my purposes. It looks like in this case the sqlite_master.name column is being detected as a long varchar datatype, which is processed as a BLOB type. That's why you get the runtime_error indicating that it's not implemented. There's a workaround here using CAST to avoid using BLOB types:

#include <iostream>
#include <string>
#include "nanodbc.h"

using namespace std;
using namespace nanodbc;

int main()
{
    connection c("Driver=sqlite;Database=this_test.db;");
    execute(c, "CREATE TABLE IF NOT EXISTS PIPES (Name TEXT);");
    result r = execute(c, "SELECT CAST(name AS text) FROM sqlite_master WHERE type = 'table';");
    r.next();
    cout << r.get<string>(0) << endl;
}

/*

$ c++ -Wall -Werror -I/usr/local/include -L/usr/local/lib -lodbc nanodbc.cpp this_test.cpp
$ ./a.out # PIPES

*/

Let me know if that also works for you on Fedora Core. I ran the above test on an OS X machine.

[lexicalunit]

From @renzo38 on December 9, 2014 7:58

Thanks for your answer, I try it on my FC20 but it crashes like my sample
code (I joined the backtrace below). I tested the same code on a RHEL6.4,
first the runtime_exception is launched without the CAST, and then it works
with this keyword. So, I think sqlite or unixODBC package is the problem.
The differences are as follow ( RHEL6.4 / FC20 ):

• sqlite-3.6.20 / sqlite-3.8.7.2
• unixODBC-2.2.14 / unixODBC-2.3.2-4
• sqliteodbc is the same

Regards.

###Stack trace under gdb

#0  0x00000035fe40f677 in sqlite3_stricmp (zLeft=0x64fff8
"sqlite_temp_master", zRight=zRight@entry=0x0) at sqlite3.c:23047
#1  0x00000035fe4105f5 in findElementWithHash (pH=<optimized out>,
pKey=pKey@entry=0x0, pHash=pHash@entry=0x7fffffffd794) at sqlite3.c:24322
#2  0x00000035fe411e3d in sqlite3HashFind (pKey=0x0, pH=<optimized out>) at
sqlite3.c:24374
#3  sqlite3FindTable (db=db@entry=0x63ae18, zName=zName@entry=0x0,
zDatabase=zDatabase@entry=0x0) at sqlite3.c:23341
#4  0x00000035fe47bdf8 in sqlite3_table_column_metadata (db=0x63ae18,
zDbName=zDbName@entry=0x0, zTableName=zTableName@entry=0x0,
zColumnName=0x0,
    pzDataType=pzDataType@entry=0x7fffffffd8c8,
pzCollSeq=pzCollSeq@entry=0x7fffffffd8d0,
pNotNull=pNotNull@entry=0x7fffffffd8bc, pPrimaryKey=pPrimaryKey@entry
=0x7fffffffd8c0,
    pAutoinc=pAutoinc@entry=0x7fffffffd8c4) at sqlite3.c:127909
#5  0x00007ffff7898266 in s3stmt_addmeta (s3stmt=s3stmt@entry=0x64ec48,
col=col@entry=0, ci=0x64e658, ci=0x64e658, d=0x639668, d=0x639668) at
sqlite3odbc.c:4004
#6  0x00007ffff7898a3c in setupdyncols (s=s@entry=0x64f9e8,
s3stmt=0x64ec48, ncolsp=ncolsp@entry=0x7fffffffda04) at sqlite3odbc.c:16597
#7  0x00007ffff78997e5 in drvprepare (stmt=stmt@entry=0x64f9e8,
query=<optimized out>, queryLen=<optimized out>) at sqlite3odbc.c:16705
#8  0x00007ffff78ab969 in SQLExecDirect (stmt=0x64f9e8, query=<optimized
out>, queryLen=<optimized out>) at sqlite3odbc.c:17073
#9  0x0000003074816262 in SQLExecDirect (statement_handle=0x64f350,
statement_text=0x64e768 "SELECT CAST(name AS text) FROM sqlite_master WHERE
type = 'table';", text_length=-3)
    at SQLExecDirect.c:421
#10 0x00000000004087ae in
nanodbc::statement::statement_impl::execute_direct (this=0x64e5f0,
conn=..., query="SELECT CAST(name AS text) FROM sqlite_master WHERE type =
'table';",
    batch_operations=1, timeout=0, statement=...) at nanodbc.cpp:1079
#11 0x0000000000404b61 in nanodbc::statement::execute_direct
(this=0x7fffffffdcb0, conn=..., query="SELECT CAST(name AS text) FROM
sqlite_master WHERE type = 'table';",
    batch_operations=1, timeout=0) at nanodbc.cpp:2545
#12 0x000000000040405d in nanodbc::execute (conn=..., query="SELECT
CAST(name AS text) FROM sqlite_master WHERE type = 'table';",
batch_operations=1, timeout=0)
    at nanodbc.cpp:2227
#13 0x0000000000402cde in main () at tst_nanodbc.cpp:16

[lexicalunit]

From @renzo38 on March 17, 2015 12:50

The unixODBC and sqlite RPM packages have been updated on Fedora Core 21 as follow:

• unixODBC-2.3.2-6
• sqlite-3.8.8.3-1

The CAST now works on this platform, this issue can be closed.

Thx

[lexicalunit]

Much thanks for the update!