# Release Notes

## 2.0.0
Release date: **2025-05-22**

This is a major release of `rdf_fdw` featuring substantial new features, improved standards compliance, and important infrastructure enhancements. Backward compatibility is preserved, but users are encouraged to review the new features and updated behavior.

### Enhancements

* PostgreSQL 9.5 and 18 (in beta1 as of this release) support.
* SPARQL `DESCRIBE` query support via the new `sparql.describe()` support function.
* New `rdfnode` data type, enabling:
  * Representation of RDF literals and IRIs with full lexical fidelity.
  * Precise round-tripping of SPARQL values within SQL.
  * Equality and order comparisons with native PostgreSQL types (e.g., `int`, `float`, `text`, `date`).
* SPARQL 1.1 Built-in Function Support via [SQL queries](https://github.com/jimjonesbr/rdf_fdw?tab=readme-ov-file#sparql-functions).
  * [Functional Forms](https://www.w3.org/TR/sparql11-query/#func-forms): 
    * `bound`, `COALESCE` and `sameTerm`.
  * [Functions on RDF Terms](https://www.w3.org/TR/sparql11-query/#func-rdfTerms):
    * `isIRI`, `isBlank`, `isLiteral`, `isNumeric`, `str`, `lang`, `datatype`, `IRI`, `BNODE`, `STRDT`, `STRLANG`, `UUID`, and `STRUUID`.
  * [Functions on Strings](https://www.w3.org/TR/sparql11-query/#func-strings): 
    * `STRLEN`, `SUBSTR`, `UCASE`, `LCASE`, `STRSTARTS`, `STRENDS`, `CONTAINS`, `STRBEFORE`, `STRAFTER`, `ENCODE_FOR_URI`, `CONCAT`, `langMatches`, `REGEX`, and `REPLACE`.
  * [Functions on Numerics](https://www.w3.org/TR/sparql11-query/#func-numerics): 
    * `abs`, `round`, `ceil`, `floor`, and `RAND`.
  * [Functions on Dates and Times](https://www.w3.org/TR/sparql11-query/#func-date-time): 
    * `year`, `month`, `day`, `hours`, `minutes`, `seconds`, `timezone`, and `tz`.
  * [Hash Functions](https://www.w3.org/TR/sparql11-query/#func-hash): 
    * `md5`.

  These functions are translated to their SPARQL equivalents when pushed down to the foreign data wrapper. 

### Minor Changes
* The `FOREIGN TABLE` option `log_sparql` is now set to `true`, if omitted. If you don't want to log the SPARQL query, consider using [`ALTER FOREIGN TABLE`](https://github.com/jimjonesbr/rdf_fdw?tab=readme-ov-file#alter-foreign-table-and-alter-server) to disable this option manually, e.g.

  ```sql
  ALTER FOREIGN TABLE myrdftable OPTIONS (ADD log_sparql 'false');
  ```

### Bug Fixes

* Query cancellation support:

  Added `CHECK_FOR_INTERRUPTS()` in key execution points to allow PostgreSQL backends to detect user-initiated query cancellations (e.g., Ctrl+C), improving long-running query handling.

### External Libraries

 * Added a new dependency: Redland RDF Library (`librdf`) — used for parsing and serializing RDF data, and supporting `DESCRIBE` queries.

## 1.3.0
Release date: **2024-09-30**

### Enhancements

* Support for PostgreSQL 9.6, 10, and 17: This adds support for the long EOL'd PostgreSQL versions 9.6 and 10. It is definitely discouraged to use these unsupported versions, but in case you're for whatever reason unable to perform an upgrade you can now use the `rdf_fdw`. 

## 1.2.0
Release date: **2024-05-22**

### Enhancements

* Pushdown support for [Math](https://www.postgresql.org/docs/current/functions-math.html), [String](https://www.postgresql.org/docs/current/functions-string.html) and [Date/Time](https://www.postgresql.org/docs/current/functions-datetime.html) functions:
  * `abs`, `ceil`, `floor`, `round`
  * `length`, `upper`, `lower`, `starts_with`, `substring`, `md5`
  * `extract(year from x)`, `extract(month from x)`, `extract(year from x)`, `extract(hour from x)`, `extract(minute from x)`, `extract(second from x)`
  * `date_part(year, x)`, `date_part('month',x)`, `date_part('year', x)`, `date_part('hour', x)`, `date_part('minute', x)`, `date_part('second', x)`

  When used in the `WHERE` clause these functions will be translated to their correspondent SPARQL `FILTER` expressions.

### Bug Fixes

* Bug fix for WHERE conditions with "inverted" arguments - that is, value in the left side (T_Const) and column in the right side (T_Var): This fixes a bug that led the pushdown of `WHERE` condiditions containing "inverted" arguments to fail, e.g `"foo" = column`, `42 > column`. Now the order of T_Const and T_Var in the arguments is irrelevant.


## 1.1.0
Release date: **2024-04-10**

### Enhancements

* [`USER MAPPING`](https://github.com/jimjonesbr/rdf_fdw?tab=readme-ov-file#create-user-mapping) support: This feature defines a mapping of a PostgreSQL user to an user in the target triplestore - `user` and `password`, so that the user can be authenticated. Requested by [Matt Goldberg](https://github.com/mgberg). 

* Pushdown suuport for [`pattern matching operators`](https://www.postgresql.org/docs/current/functions-matching.html#FUNCTIONS-LIKE) `LIKE` and `ILIKE`: these operators are now translated into SPARQL `FILTER` expressions as `REGEX` and pushed down.

* Enables usage of non-pushable data types in `FOREIGN TABLE` columns: This disables a check that raised an excepetion when data types that cannot be pushed down were used. This includes non-standard data types, such as `geometry` or `geography` from PostGIS.

### Bug Fixes

* Empty SPARQL `SELECT` clause: This fixes a bug that led some SPARQL queries to be created without any variable in the `SELECT` clause. We now use `SELECT *` in case the planner cannot identify which nodes should be retrieved, which can be a bit inefficent if we're dealing with many columns, but it is much better than an error message.

* Missing schema from foreign tables in `rdf_fdw_clone_table` calls: This fixes a bug that led the `rdf_fdw_clone_table` procedure to always look for the given `FOREIGN TABLE` in the `public` schema.

* xmlDoc* memory leak: The xml document containing the resulst sets from the SPARQL queries wasn't beeing freed after the query was complete. This led to a memory leak that could potentially cause a system crash once all available memory was consumed by the orphan documents - which is an issue for rather modest server settings that execute mutliple queries in the same session. Reported by [Filipe Pessoa](https://github.com/lfpessoa).

## 1.0.0
Release date: **2024-03-15**

Initial release. 

Support for PostgreSQL 11, 12, 13, 14, 15 and 16.

### Main Features

* Pushdown: [`LIMIT`](https://github.com/jimjonesbr/rdf_fdw?tab=readme-ov-file#limit), [`ORDER BY`](https://github.com/jimjonesbr/rdf_fdw?tab=readme-ov-file#order-by), [`DISTINCT`](https://github.com/jimjonesbr/rdf_fdw?tab=readme-ov-file#distinct), [`WHERE`](https://github.com/jimjonesbr/rdf_fdw?tab=readme-ov-file#where) with several [data types and operators](https://github.com/jimjonesbr/rdf_fdw?tab=readme-ov-file#where)
* Table copy: This introduces the procedure [`rdf_fdw_clone_table()`](https://github.com/jimjonesbr/rdf_fdw?tab=readme-ov-file#rdf_fdw_clone_table), that is designed to copy data from a `FOREIGN TABLE` into an ordinary `TABLE`. It provides the possibility to retrieve the data set in batches.
* Proxy Support for [`SERVER`](https://github.com/jimjonesbr/rdf_fdw?tab=readme-ov-file#create-server): quite handy feature in case the PostgreSQL and SPARQL endpoint servers are in different networks and can only communicate through a proxy.