Sqlight affinity varchar1/4/2024 ![]() ![]() ![]() This means in case of deparse PostgreSQL always will give us normalized value like a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11 but our fdw should also gives in WHERE predicate such values asĬurrent uuid support is very limited: no blob(16) support at all, only a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11 form works in deparse cases. For text uuid we have which implements = Let's note, we have normalized output but some possible inputs.For deparsing to blob there is uppercase and - exclude algorithm,.For blob(16) in SELECT there is blob->text->uuid grouping algorithm,.SQLite recommends both blob(16) and text data affinity for UUID, see ,.In case of uuid PostgreSQL data type I have some problems and need your advice. SQLite NULL affinity always can be transparent converted for a nullable column in PostgreSQL. - transparent transformation is possible for PostgreSQL (always or for some special values), but not implemented in sqlite_fdw.V+ - transparent transformation if appliacable.✔ - transparent transformation where PostgreSQL datatype is equal to SQLite affinity.T - cast to text in SQLite utf-8 encoding, then to PostgreSQL text with current encoding of database and then transparent transformation if applicable.If the declared type of the column contains any of the strings 'CHAR', 'CLOB', or 'TEXT' then that. If the declared type contains the string 'INT' then it is assigned INTEGER affinity. The specified datatype is just a hint and it is called type affinity. If the declared type for a column contains any of the strings "REAL", "FLOA", or "DOUB" then the column has REAL affinity.Hello, discussion in #66 and ended PR #79 without SQL behaviour change I am trying to implement some SQL behaviour from data type - affinity table and draft any tests for this cases. Any column with the exception of INTEGER PRIMARY KEY can hold values of any type. If the declared type for a column contains the string "BLOB" or if no type is specified then the column has affinity NONE. Notice that the type VARCHAR contains the string "CHAR" and is thus assigned TEXT affinity. If the declared type of the column contains any of the strings "CHAR", "CLOB", or "TEXT" then that column has TEXT affinity. If the declared type contains the string "INT" then it is assigned INTEGER affinity. The affinity of a column is determined by the declared type of the column, according to the following rules in the order shown: The preferred storage class for a column is called its "affinity".Įach column in an SQLite 3 database is assigned one of the following type affinities: Consider the following quick recap on SQLite data types: NULL: Indicates missing information or unknown. This feature alone makes SQLite highly adaptable to diverse needs. It is just that some columns, given the choice, will prefer to use one storage class over another. It allows you to store any type of data in any column irrespective of the declared type. Any column can still store any type of data. The important idea here is that the type is recommended, not required. The type affinity of a column is the recommended type for data stored in that column. ![]() ![]() In order to maximize compatibility between SQLite and other database engines, SQLite supports the concept of "type affinity" on columns. The value is a blob of data, stored exactly as it was input. The value is a text string, stored using the database encoding (UTF-8, UTF-16BE or UTF-16LE).īLOB. The value is a floating point value, stored as an 8-byte IEEE floating point number. The value is a signed integer, stored in 1, 2, 3, 4, 6, or 8 bytes depending on the magnitude of the value. However, the dynamic typing in SQLite allows it to do things which are not possible in traditional rigidly typed databases.Įach value stored in an SQLite database (or manipulated by the database engine) has one of the following storage classes: The dynamic type system of SQLite is backwards compatible with the more common static type systems of other database engines in the sense that SQL statement that work on statically typed databases should work the same way in SQLite. In SQLite, the datatype of a value is associated with the value itself, not with its container. SQLite uses a general dynamic type system. ![]()
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