Building SQLite for WASM Fails with “must use ‘struct’ tag to refer to type ‘Wal'” in Non-Amalgamation Configurations

Building SQLite for WASM Fails with “must use ‘struct’ tag to refer to type ‘Wal'” in Non-Amalgamation Configurations

BySQLite.work Team

Compilation Error Due to Missing Type Declaration in WAL Module Issue Overview A compilation error occurs when building SQLite for WebAssembly (WASM) with the –enable-amalgamation=no flag, specifically in the Write-Ahead Logging (WAL) module. The error manifests as: /projects/sqlite/repo/bld/../src/wal.c:747:3: error: must use ‘struct’ tag to refer to type ‘Wal’ 747 | Wal *pWal, /* The WAL…

Running SQLite3 on Raspberry Pi Pico: Challenges and Solutions

Running SQLite3 on Raspberry Pi Pico: Challenges and Solutions

BySQLite.work Team

Issue Overview: Running SQLite3 on Microcontrollers with Limited Resources Running SQLite3 on microcontrollers, such as the Raspberry Pi Pico (RP2040), presents a unique set of challenges due to the constrained resources typical of these devices. The Raspberry Pi Pico, equipped with the RP2040 microcontroller, offers limited RAM (264 KB) and flash storage (2 MB), which…

Stability and Determinism in SQLite JSON Function Outputs for Hash Integrity

Stability and Determinism in SQLite JSON Function Outputs for Hash Integrity

BySQLite.work Team

Understanding JSON Function Determinism and Version Consistency in SQLite Issue Overview: JSON Output Stability for Hash-Based Integrity Checks The core issue revolves around ensuring that JSON strings generated by SQLite’s JSON functions remain stable (i.e., byte-for-byte identical) across SQLite versions and function variations. This stability is critical when using JSON outputs to generate hash values…

Detecting and Blocking Unauthorized DDL Queries in SQLite

Detecting and Blocking Unauthorized DDL Queries in SQLite

BySQLite.work Team

Issue Overview: Unintended Schema Modifications via DDL Statements The challenge of detecting and rejecting Data Definition Language (DDL) queries—specifically CREATE, DROP, and ALTER statements—arises in environments where database schema integrity is critical. Applications that allow user-generated SQL input, multi-tenant systems, or sandboxed database interfaces must prevent unauthorized modifications to table structures, indexes, triggers, or views….

Accessing sqlite3_sql APIs from Authorization Callback: Limitations and Workarounds

Accessing sqlite3_sql APIs from Authorization Callback: Limitations and Workarounds

BySQLite.work Team

Understanding the Authorization Callback Mechanism in SQLite The authorization callback in SQLite, set via the sqlite3_set_authorizer function, is a powerful feature that allows developers to control and monitor database operations at a granular level. This callback is invoked during the preparation phase of SQL statements, enabling the application to authorize or deny specific actions such…

Using Stored Generated Columns for Immutable Timestamps in SQLite

Using Stored Generated Columns for Immutable Timestamps in SQLite

BySQLite.work Team

Understanding the Limitations of Stored Generated Columns for Timestamps The concept of using stored generated columns in SQLite to create immutable timestamps is an appealing one, especially for developers looking to enforce data integrity and prevent unauthorized modifications to timestamp fields. However, SQLite imposes certain restrictions on generated columns that make this approach currently unfeasible….

SQLite Zero-Length File Creation and Database Header Initialization Issue

SQLite Zero-Length File Creation and Database Header Initialization Issue

BySQLite.work Team

SQLite’s Handling of Empty Files and Database Header Initialization SQLite is a lightweight, serverless, and self-contained database engine that is widely used in applications ranging from embedded systems to mobile apps. One of its key features is its simplicity in creating and managing database files. However, this simplicity can sometimes lead to unexpected behaviors, particularly…

Why REPLACE Bypasses UPDATE Triggers in SQLite and How to Enforce Constraints

Why REPLACE Bypasses UPDATE Triggers in SQLite and How to Enforce Constraints

BySQLite.work Team

Issue Overview: Trigger Behavior Discrepancies Between REPLACE and UPDATE Operations SQLite’s conflict resolution mechanisms, such as INSERT OR REPLACE, are designed to handle constraint violations by deleting and reinserting rows instead of directly updating them. This creates an apparent inconsistency when developers implement triggers to restrict modifications to a table. For example, a BEFORE UPDATE…

CAST AS NUMERIC Returns REAL Instead of INTEGER for Float-Like Values

CAST AS NUMERIC Returns REAL Instead of INTEGER for Float-Like Values

BySQLite.work Team

Understanding the CAST Expression Behavior in SQLite The CAST expression in SQLite is a powerful tool for converting data types, but its behavior can sometimes be counterintuitive, especially when dealing with numeric conversions. One such scenario involves the conversion of floating-point-like values to NUMERIC, where the result is unexpectedly a REAL instead of an INTEGER….

Appending SQLite Database to Executable File Using VACUUM INTO and apndvfs

Appending SQLite Database to Executable File Using VACUUM INTO and apndvfs

BySQLite.work Team

Understanding the Core Challenge: Merging Standalone Databases into Executable-Bound Appended Storage The central challenge revolves around integrating a standalone SQLite database file (stored as a separate *.db, *.sqlite, or *.db3 file) into an existing executable file in a way that appends the database to the executable without overwriting its original content. This is distinct from…