How Do I Fix SQLITE_NOMEM Error on Linux 64-Bit with LabVIEW

I hit a wall trying to call SQLite from LabVIEW on Linux x86_64 (RHEL6). The exact same VI worked beautifully on Win32/Win64/Linux32, but on Linux64 I kept running into two nasty problems: either LabVIEW would crash on sqlite3_step() or I’d get a SQLITE_NOMEM out of memory error.

I’ll show you the first code I used, the exact error, what it really means, the fixed code and build flags that solved it for me, and then some practice functionality I added to prove the setup is reliable.

The First Code I Started With

My flow was super simple:

1. Open connection
2. DROP TABLE IF EXISTS MyTable;
3. CREATE TABLE MyTable (Id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, Temperature FLOAT NOT NULL, Sensor TEXT NULL);
4. Insert a row like: INSERT INTO MyTable (Sensor, Temperature) VALUES ("%s", "%0.2f");

And here’s the C function I wrapped for LabVIEW:

// first_try.c (simplified)
#include <sqlite3.h>

int create_table(sqlite3* db) {
    const char* sql =
        "CREATE TABLE MyTable ("
        "  Id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,"
        "  Temperature FLOAT NOT NULL,"
        "  Sensor TEXT NULL"
        ");";

    sqlite3_stmt* stmt = NULL;
    int rc = sqlite3_prepare_v2(db, sql, -1, &stmt, NULL);
    if (rc != SQLITE_OK) return rc;   // (at first I wasn’t checking this!)

    rc = sqlite3_step(stmt);          // <-- crash on 3.8.7, SQLITE_NOMEM on 3.7.5
    int rc2 = sqlite3_finalize(stmt);
    return (rc == SQLITE_OK || rc == SQLITE_DONE) ? rc2 : rc;
}

I called this function through a LabVIEW wrapper that already worked on other platforms.

The Error I Saw

• With SQLite 3.8.7 → LabVIEW crashed at sqlite3_step()
• With SQLite 3.7.5 → sqlite3_step() returned SQLITE_NOMEM
• Same results with two different LabVIEW wrappers

At first glance it looked like a memory leak or out-of-memory issue. But it wasn’t.

What the Error Really Meant

This wasn’t SQLite genuinely running out of memory. It was an ABI/build mismatch on Linux64:

• 64-bit process, 64-bit lib: I had LabVIEW 64-bit calling into my own compiled 64-bit libsqlite3.so. Good.
• ABI mismatches: If the wrapper’s typedefs (like sqlite3_int64) or calling signatures don’t exactly line up with how the library was built, you end up with stack/heap corruption. That leads to weird behavior: sometimes a crash, sometimes a fake SQLITE_NOMEM.
• Compiler flags: On Linux64, you must build SQLite with -fPIC and link with -ldl -lpthread. Without them, undefined behavior creeps in.
• String parameters: I was passing formatted SQL strings like "%s" and "%0.2f" instead of using ? placeholders with proper binding. That’s fragile and error-prone.

In short: not real out-of-memory it was corrupted state caused by build and usage problems.

The Fix That Made it Stable

Rebuild SQLite Cleanly

# Example build with amalgamation source
gcc -fPIC -O2 -DSQLITE_THREADSAFE=1 -DSQLITE_DEFAULT_MEMSTATUS=1 \
    -DSQLITE_ENABLE_COLUMN_METADATA \
    -DSQLITE_ENABLE_FTS5 \
    -c sqlite3.c

gcc -shared -o libsqlite3.so sqlite3.o -ldl -lpthread

• -fPIC is critical on x86_64.
• -ldl -lpthread are required.
• Only enable the features you actually need.

I installed it into /usr/local/lib and updated ldconfig.

Use Prepared Statements and Bind Values

Here’s my fixed code:

// fixed_create_insert.c
#include <sqlite3.h>
#include <string.h>

int create_table(sqlite3* db) {
    const char* sql =
        "CREATE TABLE IF NOT EXISTS MyTable ("
        "  Id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,"
        "  Temperature REAL NOT NULL,"
        "  Sensor TEXT NULL"
        ");";

    sqlite3_stmt* stmt = NULL;
    int rc = sqlite3_prepare_v2(db, sql, -1, &stmt, NULL);
    if (rc != SQLITE_OK) return rc;

    rc = sqlite3_step(stmt);
    int rc2 = sqlite3_finalize(stmt);
    return (rc == SQLITE_DONE ? SQLITE_OK : rc) ?: rc2;
}

int insert_row(sqlite3* db, const char* sensor, double temperature) {
    const char* sql = "INSERT INTO MyTable (Sensor, Temperature) VALUES (?, ?);";
    sqlite3_stmt* stmt = NULL;
    int rc = sqlite3_prepare_v2(db, sql, -1, &stmt, NULL);
    if (rc != SQLITE_OK) return rc;

    rc = sqlite3_bind_text(stmt, 1, sensor ? sensor : "", -1, SQLITE_TRANSIENT);
    if (rc != SQLITE_OK) { sqlite3_finalize(stmt); return rc; }

    rc = sqlite3_bind_double(stmt, 2, temperature);
    if (rc != SQLITE_OK) { sqlite3_finalize(stmt); return rc; }

    rc = sqlite3_step(stmt);  // should return SQLITE_DONE
    int rc2 = sqlite3_finalize(stmt);

    return (rc == SQLITE_DONE ? SQLITE_OK : rc) ?: rc2;
}

Fix LabVIEW Call Library Function Node settings

• Library path → my rebuilt 64-bit libsqlite3.so
• Calling convention → cdecl
• Pointer arguments → pointer-sized integer or numeric type
• Strings → C String Pointer
• Return type → Signed 32-bit Int
• Thread safety → compiled with -DSQLITE_THREADSAFE=1

Always Check Return Codes

Never call sqlite3_step() if sqlite3_prepare_v2() fails. Always log sqlite3_errmsg(db) for visibility.

Practice Functionality

To prove it was stable, I added some “practice” functions:

• Insert many with transaction → stress test
• Enable WAL mode → ensures proper pthread linkage
• Memory stats → confirm no leaks
• Parameterized selects → test UTF-8 handling

Example:

int count_by_sensor(sqlite3* db, const char* sensor, int* outCount) {
    const char* sql = "SELECT COUNT(*) FROM MyTable WHERE Sensor = ?;";
    sqlite3_stmt* st = NULL;
    int rc = sqlite3_prepare_v2(db, sql, -1, &st, NULL);
    if (rc != SQLITE_OK) return rc;

    rc = sqlite3_bind_text(st, 1, sensor, -1, SQLITE_TRANSIENT);
    if (rc != SQLITE_OK) { sqlite3_finalize(st); return rc; }

    rc = sqlite3_step(st);
    if (rc == SQLITE_ROW) *outCount = sqlite3_column_int(st, 0);

    int rc2 = sqlite3_finalize(st);
    return (rc == SQLITE_ROW ? SQLITE_OK : rc) ?: rc2;
}

This proved parameter binding and return values worked smoothly from LabVIEW.

Final Thought

The SQLITE_NOMEM error turned out to be a red herring I wasn’t actually running out of memory. The real issues were a shared library that wasn’t built with -fPIC -ldl -lpthread, ABI mismatches between LabVIEW’s wrapper and SQLite’s compiled types, and fragile ad-hoc SQL strings instead of proper parameter binding. Once I rebuilt SQLite correctly, switched to prepared statements, and fixed my CLFN configuration, both the crash and the false SQLITE_NOMEM error disappeared. Now my LabVIEW + SQLite setup runs smoothly on Linux 64-bit, and with the extra practice functions I added, it handles real workloads without falling over.