Issue Overview: Blob I/O Accessing Incorrect Columns in Tables with Virtual Generated Columns The core issue revolves around a mismatch in column indexing when performing Blob I/O operations on SQLite tables that contain virtual generated columns. Specifically, when a table includes a virtual generated column, attempting to write to a BLOB column using the sqlite3_blob_open()…
Understanding Slow SELECT Performance on Composite Index Criteria Issue Overview: Query Performance Degradation with Multiple WHERE Clauses The core problem revolves around a SQLite query experiencing significant latency (150 ms) when filtering on two columns (ACCOUNT_ID and ENTITY), despite individual filters on ACCOUNT_ID alone executing efficiently (2 ms). The table UNIQUE_ENTITIES has separate indexes on…
Unexpected MAX() Window Function Behavior with Specific Range Preceding Values The core issue involves unexpected results from the MAX() window function when applied to a dataset with a specific range-based window frame in SQLite. A user observed that a window defined with RANGE 365 PRECEDING produced a lower value than a window defined with RANGE…
SQLite LIKE Operator Case Sensitivity Mechanics and Limitations The SQLite LIKE operator’s default case sensitivity behavior depends on compile-time options and runtime pragmas. By default, when SQLite is built without ICU (International Components for Unicode) support, the LIKE operator performs case-insensitive matches for ASCII characters only, while treating Unicode characters as case-sensitive. This behavior can…
Schema Change Detection and Error Logger Invocation Issue Overview The core issue revolves around the SQLite error logging callback being invoked spuriously when a schema change is detected by another connection. This occurs even when the schema change is not an actual error from SQLite’s perspective. Specifically, when a connection prepares a statement that references…
Understanding the Sorting Behavior in SQLite Queries When working with SQLite, sorting query results is a fundamental operation that can sometimes yield unexpected outcomes, especially when dealing with calculated columns. The core issue here revolves around the sorting of a calculated column (Diff) in a query that aggregates and calculates multiple metrics for teams in…
Understanding the Core Challenge of ROWID Conversion The central challenge in this scenario revolves around modifying an existing SQLite table to transition from relying on the implicit ROWID mechanism to using an explicitly defined ROWID column. SQLite automatically assigns a 64-bit signed integer ROWID (or _ROWID_/OID) to every table unless the table is explicitly defined…
Schema Change Visibility and Cached Metadata Across Multiple Connections When multiple connections are opened to the same SQLite database file, each connection maintains an independent schema cache to optimize performance. This cache stores metadata about database objects (tables, indexes, etc.). When a schema change occurs on one connection (e.g., creating a table), other connections do…
Issue Overview: Sorting Behavior of IN Operator Values in SQLite Virtual Tables When working with SQLite virtual tables, developers often encounter scenarios where the behavior of the IN operator becomes critical, especially when optimizing for performance or ensuring correct query results. One such scenario involves the sorting of values returned by the sqlite3_vtab_in_first and sqlite3_vtab_in_next…
Understanding the Performance Bottleneck in SELECT COUNT(DISTINCT) Queries The core issue revolves around the performance of a SELECT COUNT(DISTINCT) query on a large SQLite table. The table in question, my_data, contains approximately 4 million records, with a data_id column that stores 16-character hexadecimal strings. While the data_id column is indexed, the query performance degrades significantly…