Issue Overview: Mismatch Between Expected and Actual Character Counts in Hebrew UTF-8 Strings The core issue arises when working with Hebrew text stored in SQLite databases, where functions like SUBSTR() and LENGTH() return values that appear to count bytes rather than "logical characters." This is particularly confusing when dealing with Hebrew vowels (niqqud), cantillation marks,…
Issue Overview: FTS5 snippet() Function Misbehavior in Non-Matching Columns The core issue revolves around the behavior of the snippet() function in SQLite’s FTS5 (Full-Text Search) module. Specifically, the function is designed to return a formatted snippet of text from a specified column in an FTS5 table, highlighting the search terms within the snippet. However, the…
Issue Overview: PRAGMA reverse_unordered_selects and Result Ambiguity in SQLite The core issue revolves around the behavior of SQLite when the PRAGMA reverse_unordered_selects is enabled or disabled, leading to different results for the same SELECT statement. This behavior is observed in a specific scenario involving a temporary table, a view, and a SELECT query with a…
Understanding Collation Inheritance in Expressions and Columns Core Discrepancy: Collation Application in CASE Expressions vs Direct Column References The central issue revolves around how SQLite applies collation rules when comparing values in an IN clause, particularly when one side is a column with an explicit collation and the other is an expression (like a CASE…
Understanding the Impact of SQLITE_OmitOrderBy on Query Results Issue Overview The core issue revolves around inconsistent query results when the SQLITE_OmitOrderBy optimization is enabled or disabled in SQLite. This optimization is designed to remove unnecessary ORDER BY clauses in subqueries to improve query performance. However, its application can lead to unexpected results, particularly in queries…
Issue Overview: Mismatched Database Keys and Application Index Requirements When integrating SQLite databases with external applications, developers often encounter challenges where the database’s integer primary keys (IDs) don’t align with the application’s indexing requirements. This mismatch occurs when the application expects dense, sequential indices (e.g., 0,1,2,…) for efficient array/bitmask operations, but the database uses non-sequential…
Issue Overview: Assertion Failure in NATURAL JOIN with QueryFlattener Optimization The core issue revolves around an assertion failure in SQLite when executing a specific query involving a NATURAL JOIN between a table and a view. The failure occurs in the sqlite3VdbeExec function, specifically at the assertion memIsValid(&aMem[pOp->p1]). This assertion ensures that a memory cell (aMem)…
Subquery Evaluation Interference During Single-Pass UPDATE Optimization Issue Overview The core problem revolves around an SQLite UPDATE query that unintentionally modifies rows due to interference between a subquery in the WHERE clause and a single-pass optimization mechanism. The scenario involves a table t1 with two rows: (3, NULL) and (6, -54). Three test cases highlight…
Issue Overview: Schema Aliases and Foreign Key Constraints in SQLite When working with SQLite, one of the most powerful features is the ability to attach multiple databases to a single connection using the ATTACH command. This allows you to reference tables across different databases as if they were part of a single schema. However, this…
Issue Overview: Foreign Key Constraint Violations During Changeset Application When applying changesets in SQLite using the session extension, a common challenge arises when attempting to insert or update records in a child table that references a parent table via a foreign key constraint. If a record in the changeset references a non-existent parent record, SQLite…