docs: update driver status table (#1797)

Fixes #1786.

docs/source/driver/postgresql.rst

@@ -165,6 +165,15 @@ The PostgreSQL driver mostly supports features defined in the ADBC API
 specification 1.0.0, but not all cases are fully implemented
 (particularly around bind parameters and prepared statements).
 
+Bind Parameters and Prepared Statements
+---------------------------------------
+
+The PostgreSQL driver only supports executing prepared statements with
+parameters that do not return result sets (basically, an INSERT with
+parameters).  Queries that return result sets are difficult with prepared
+statements because the driver is built around using COPY for best
+performance, which is not supported in this context.
+
 Bulk Ingestion
 --------------
 

docs/source/driver/status.rst

@@ -24,7 +24,7 @@ Implementation Status
 
 **Experimental** drivers are not feature-complete and the implementation is still progressing.
 **Beta** drivers are (mostly) feature-complete but have only been available for a short time.
-**Stable** drivers are feature-complete (as much as possible for the underlying database) and have been available/tested for a while.
+**Stable** drivers are (mostly) feature-complete (as much as possible for the underlying database) and have been available/tested for a while.
 
 .. list-table::
    :header-rows: 1
@@ -42,7 +42,7 @@ Implementation Status
    * - Flight SQL (Go)
      - C, Go
      - Go
-     - Beta
+     - Stable
 
    * - Flight SQL (Java)
      - Java
@@ -57,17 +57,17 @@ Implementation Status
    * - PostgreSQL
      - C
      - C++
-     - Beta
+     - Stable
 
    * - SQLite
      - C
      - C
-     - Beta
+     - Stable
 
    * - Snowflake
      - C, Go
      - Go
-     - Experimental
+     - Stable
 
 .. [#supported-languages] C drivers are usable from Go, Python, and Ruby as well.
 
@@ -183,7 +183,7 @@ Update Queries
    * - PostgreSQL
      - N/A
      - N/A
-     - Y
+     - Y [#postgresql-prepared]_
      - Y
      - Y
      - Y
@@ -196,6 +196,12 @@ Update Queries
      - Y
      - Y
 
+.. [#postgresql-prepared] The PostgreSQL driver only supports executing
+   prepared statements with parameters that do not return result sets
+   (basically, an INSERT with parameters).  Queries that return result sets
+   are difficult with prepared statements because the driver is built around
+   using COPY for best performance, which is not supported in this context.
+
 .. list-table:: Connection/database-level features
    :header-rows: 1
 
@@ -207,7 +213,7 @@ Update Queries
    * - Flight SQL (Go)
      - N
      - Y
-     - N
+     - Y
 
    * - Flight SQL (Java)
      - Y
@@ -222,7 +228,7 @@ Update Queries
    * - PostgreSQL
      - Y
      - Y
-     - N
+     - Y
 
    * - SQLite
      - Y