pub enum SchemaFormat {
Format1,
Format2,
Format3,
Format4,
}Expand description
§Schema format number (4 Bytes)
The schema format number is a 4-byte big-endian integer at offset 44. The schema format number is similar to the file format read and write version numbers at offsets 18 and 19 except that the schema format number refers to the high-level SQL formatting rather than the low-level b-tree formatting. Four schema format numbers are currently defined:
-
Format 1 is understood by all versions of Sqlite back to version 3.0.0 (2004-06-18).
-
Format 2 adds the ability of rows within the same table to have a varying number of columns, in order to support the ALTER TABLE … ADD COLUMN functionality. Support for reading and writing format 2 was added in Sqlite version 3.1.3 on 2005-02-20.
-
Format 3 adds the ability of extra columns added by ALTER TABLE … ADD COLUMN to have non-NULL default values. This capability was added in Sqlite version 3.1.4 on 2005-03-11.
-
Format 4 causes Sqlite to respect the DESC keyword on index declarations. (The DESC keyword is ignored in indexes for formats 1, 2, and 3.) Format 4 also adds two new boolean record type values (serial types 8 and 9). Support for format 4 was added in Sqlite 3.3.0 on 2006-01-10.
New database files created by Sqlite use format 4 by default. The legacy_file_format pragma can be used to cause Sqlite to create new database files using format 1. The format version number can be made to default to 1 instead of 4 by setting SQLITE_DEFAULT_FILE_FORMAT=1 at compile-time.