Understanding the Need for Consistent Query Results Across SQLite Versions When working with SQLite, a common expectation is that the same query will yield identical results across different versions of the database engine. This assumption is rooted in the belief that SQLite, as a stable and mature database system, maintains backward compatibility and consistency in…
Issue Overview: "UNIQUE constraint failed" Error in UPSERT with UPDATE Trigger The core issue revolves around a "UNIQUE constraint failed" error that occurs when executing an UPSERT operation (INSERT … ON CONFLICT DO UPDATE) in SQLite, particularly when an AFTER UPDATE trigger is defined on the target table. The trigger attempts to perform an INSERT…
Crash Scenario and Context in SQLite 3.40.0 A critical issue was identified in SQLite version 3.40.0 where executing the query SELECT * FROM zipfile(NULL) results in a segmentation fault (SIGSEGV). The crash occurs due to an unhandled NULL pointer dereference within the zipfile extension when attempting to open a file. The stack trace provided by…
Inconsistent NULL Pointer Checks in sqlite3_value_* Function Family Leading to Crashes The SQLite C/C++ interface provides a suite of functions under the sqlite3_value_* family to extract or compute values from SQL expressions, user-defined functions (UDFs), and virtual tables. These functions are critical for type conversion, data extraction, and memory management. However, an inconsistency exists in…
Decoding the pragma_function_list Table Structure and Column Meanings The pragma_function_list in SQLite is a powerful tool for introspection, allowing users to query metadata about the available SQL functions in their database. However, the documentation surrounding this pragma is sparse, leaving many users to infer the meanings of its columns and the flags it exposes. This…
Understanding the Misinterpretation of In-Memory URI as NTFS Alternate Data Stream The core issue arises when attempting to create an in-memory SQLite database using a URI-formatted connection string on Windows systems with NTFS. Instead of the database residing purely in memory, the system creates a file named "file" with an NTFS Alternate Data Stream (ADS)…
Understanding the Need for Master-Slave Replication in SQLite SQLite is renowned for its simplicity, speed, and ease of integration, making it a popular choice for embedded database systems. However, one of its limitations is the lack of built-in support for master-slave replication, a feature often required for applications that need high availability, fault tolerance, and…
Unexpected "Unsafe Use of json_extract()" Errors in Views with trusted_schema=0 The core issue arises when executing queries against views containing JSON functions like json_extract() after disabling the trusted_schema pragma in SQLite versions ≥3.37.0. This manifests as a parse error: "unsafe use of json_extract()", despite the function being deterministic and having no obvious security risks. The…
Issue Overview: Unexpected File Access Permissions with –safe Flag in SQLite CLI The SQLite command-line interface (CLI) includes a –safe flag designed to restrict access to functions and commands that could modify the host system or leak sensitive data. According to official documentation, enabling –safe should disable SQL functions such as readfile(), writefile(), edit(), fts3_tokenizer(),…
Issue Overview: Missing Data in Multi-Table JOIN Operations When executing a multi-table JOIN query in SQLite, encountering an empty result set—even when the query executes without errors—is a common frustration. This occurs when the logical conditions binding the tables together fail to produce matching rows. The core problem revolves around the interplay of four elements:…