Here is a list of all documented namespaces with brief descriptions:

[detail level 123]

►Npqxx	The home of all libpqxx classes, functions, templates, etc
►Ninternal	Internal items for libpqxx' own use. Do not use these yourself
Npq	Forward declarations of libpq types as needed in libpqxx headers
Carray_string_traits	String traits for SQL arrays
Cbasic_robusttransaction	Helper base class for the robusttransaction class template
Cbasic_transaction	Helper base class for the transaction class template
Cc_params	Internal type: encode statement parameters
Ccallgate	Base class for call gates
Cdisallowed_ambiguous_char_conversion	Deliberately nonfunctional conversion traits for `char` types
Cdynamic_params
Cenum_traits	Helper class for defining enum conversions
Cfloat_traits	String traits for builtin floating-point types
Cglyph_scanner	Wrapper struct template for "find next glyph" functions
Cglyph_scanner< encoding_group::BIG5 >
Cglyph_scanner< encoding_group::EUC_CN >
Cglyph_scanner< encoding_group::EUC_JP >
Cglyph_scanner< encoding_group::EUC_KR >
Cglyph_scanner< encoding_group::EUC_TW >
Cglyph_scanner< encoding_group::GB18030 >
Cglyph_scanner< encoding_group::GBK >
Cglyph_scanner< encoding_group::JOHAB >
Cglyph_scanner< encoding_group::MONOBYTE >
Cglyph_scanner< encoding_group::MULE_INTERNAL >
Cglyph_scanner< encoding_group::SJIS >
Cglyph_scanner< encoding_group::UHC >
Cglyph_scanner< encoding_group::UTF8 >
Cintegral_traits	String traits for builtin integral types (though not bool)
Cnotice_waiters	Various callbacks waiting for a notice to come in
Cresult_iter	Iterator for looped unpacking of a result
Cresult_iteration
Csql_cursor	Cursor with SQL positioning semantics
Cstream_from_input_iterator	Input iterator for stream_from
Cstream_input_iteration	Iteration over a stream_query
Cstream_query	Stream query results from the database. Used by transaction_base::stream
Cstream_query_end_iterator	The `end()` iterator for a `stream_query`
Cstream_query_input_iterator	Input iterator for stream_query
Nprepare
Cargument_error	Invalid argument passed to libpqxx, similar to std::invalid_argument
Carray	An SQL array received from the database
Carray_parser	Low-level parser for C++ arrays
Cbasic_fieldstream	Input stream that gets its data from a result field
Cbasic_ilostream	Input stream that gets its data from a large object
Cbasic_lostream	Stream that reads and writes a large object
Cbasic_olostream	Output stream that writes data back to a large object
Cbinarystring	Binary data corresponding to PostgreSQL's "BYTEA" binary-string type
Cblob
Cbroken_connection	Exception class for lost or failed backend connection
Cbyte_char_traits	Custom `std::char_trast` if the compiler does not provide one
Ccheck_violation
Cconnecting	An ongoing, non-blocking stepping stone to a connection
Cconnection	Connection to a database
Cconst_result_iterator	Iterator for rows in a result. Use as result::const_iterator
Cconst_reverse_result_iterator	Reverse iterator for result. Use as result::const_reverse_iterator
Cconst_reverse_row_iterator	Reverse iterator for a row. Use as row::const_reverse_iterator
Cconst_row_iterator	Iterator for fields in a row. Use as row::const_iterator
Cconversion_error	Value conversion failed, e.g. when converting "Hello" to int
Cconversion_overrun	Could not convert value to string: not enough buffer space
Ccursor_base	Common definitions for cursor types
Cdata_exception	Error in data provided to SQL statement
Cdbtransaction	Abstract transaction base class: bracket transactions on the database
Cdeadlock_detected	The ongoing transaction has deadlocked. Retrying it may help
Cdisk_full
Cerrorhandler
Cexclusive_bound	An exclusive boundary value to a pqxx::range
Cfailure	Run-time failure encountered by libpqxx, similar to std::runtime_error
Cfeature_not_supported	Database feature not supported in current setup
Cfield	Reference to a field in a result set
Cfield_streambuf
Cforbidden_conversion	String traits for a forbidden type conversion
Cforeign_key_violation
Cfrom_query_t	Marker for stream_from constructors: "stream from query."
Cfrom_table_t	Marker for stream_from constructors: "stream from table."
Chas_generic_char_traits
Chas_generic_char_traits< TYPE, std::void_t< decltype(std::char_traits< TYPE >::eof)> >
Cin_doubt_error	"Help, I don't know whether transaction was committed successfully!"
Cinclusive_bound	An inclusive boundary value to a pqxx::range
Cinsufficient_privilege
Cinsufficient_resources	Resource shortage on the server
Cintegrity_constraint_violation
Cinternal_error	Internal error in libpqxx library
Cinvalid_cursor_name
Cinvalid_cursor_state
Cinvalid_sql_statement_name
Clargeobject	Identity of a large object
Clargeobject_streambuf	Streambuf to use large objects in standard I/O streams
Clargeobjectaccess	Accessor for large object's contents
Cno_bound	An unlimited boundary value to a pqxx::range
Cno_null	Nullness traits describing a type which does not have a null value
Cnontransaction	Simple "transaction" class offering no transactional integrity
Cnot_null_violation
Cnotification	An incoming notification
Cnotification_receiver
Cnullness	Traits describing a type's "null value," if any
Cnullness< binarystring >
Cnullness< bytes >
Cnullness< bytes_view >
Cnullness< char * >
Cnullness< char const * >
Cnullness< char[N]>
Cnullness< ENUM, std::enable_if_t< std::is_enum_v< ENUM > > >	Nullness: Enums do not have an inherent null value
Cnullness< range< TYPE > >	A range type does not have an innate null value
Cnullness< std::array< T, N > >
Cnullness< std::monostate >
Cnullness< std::nullopt_t >
Cnullness< std::nullptr_t >
Cnullness< std::optional< T > >
Cnullness< std::shared_ptr< T > >
Cnullness< std::string >
Cnullness< std::string_view >	There's no real null for `std::string_view`
Cnullness< std::stringstream >
Cnullness< std::unique_ptr< T > >
Cnullness< std::variant< T... > >
Cnullness< std::vector< T, Args... > >
Cnullness< T, std::enable_if_t< std::is_arithmetic_v< T > > >	The built-in arithmetic types do not have inherent null values
Cnullness< zview >
Cout_of_memory
Cparams	Build a parameter list for a parameterised or prepared statement
Cpipeline	Processes several queries in FIFO manner, optimized for high throughput
Cplaceholders	Generate parameter placeholders for use in an SQL statement
Cplpgsql_error	PL/pgSQL error
Cplpgsql_no_data_found
Cplpgsql_raise	Exception raised in PL/pgSQL procedure
Cplpgsql_too_many_rows
Cprepped	A string that is the name of a prepared statement
Cprotocol_violation	Exception class for micommunication with the server
Cquiet_errorhandler
Crange	A C++ equivalent to PostgreSQL's range types
Crange_bound	A range boundary value
Crange_error	Something is out of range, similar to std::out_of_range
Crestrict_violation
Cresult	Result set containing data returned by a query or command
Crow	Reference to one row in a result
Cserialization_failure	Transaction failed to serialize. Please retry it
Csql_error	Exception class for failed queries
Cstateless_cursor	"Stateless cursor" class: easy API for retrieving parts of result sets
Cstatement_completion_unknown	We can't tell whether our last statement succeeded
Cstream_from	Stream data from the database
Cstream_query
Cstream_to	Efficiently write data directly to a database table
Cstring_traits	Traits class for use in string conversions
Cstring_traits< binarystring >	String conversion traits for `binarystring`
Cstring_traits< bool >
Cstring_traits< bytes >
Cstring_traits< bytes_view >
Cstring_traits< char * >	String traits for non-const C-style string ("pointer to char")
Cstring_traits< char >	You cannot convert a `char` to/from SQL
Cstring_traits< char const * >	String traits for C-style string ("pointer to char const")
Cstring_traits< char[N]>	String traits for C-style string constant ("pointer to array of char")
Cstring_traits< double >
Cstring_traits< float >
Cstring_traits< int >
Cstring_traits< long >
Cstring_traits< long double >
Cstring_traits< long long >
Cstring_traits< pqxx::internal::encoding_group >
Cstring_traits< range< TYPE > >	String conversions for a range type
Cstring_traits< short >
Cstring_traits< signed char >	You cannot convert a `signed char` to/from SQL
Cstring_traits< std::array< T, N > >
Cstring_traits< std::byte >	You cannot convert a `std::byte` to/from SQL
Cstring_traits< std::monostate >
Cstring_traits< std::nullopt_t >
Cstring_traits< std::nullptr_t >
Cstring_traits< std::optional< T > >
Cstring_traits< std::shared_ptr< T > >
Cstring_traits< std::string >
Cstring_traits< std::string_view >	String traits for `string_view`
Cstring_traits< std::stringstream >
Cstring_traits< std::unique_ptr< T, Args... > >
Cstring_traits< std::variant< T... > >
Cstring_traits< std::vector< T, Args... > >
Cstring_traits< unsigned >
Cstring_traits< unsigned char >	You cannot convert an `unsigned char` to/from SQL
Cstring_traits< unsigned long >
Cstring_traits< unsigned long long >
Cstring_traits< unsigned short >
Cstring_traits< zview >	String traits for `zview`
Csubtransaction	"Transaction" nested within another transaction
Csyntax_error
Cthread_safety_model	Descriptor of library's thread-safety model
Ctoo_many_connections
Ctransaction_base	Interface definition (and common code) for "transaction" classes
Ctransaction_focus	Base class for things that monopolise a transaction's attention
Ctransaction_rollback	The backend saw itself forced to roll back the ongoing transaction
Cundefined_column
Cundefined_function
Cundefined_table
Cunexpected_null	Could not convert null value: target type does not support null
Cunexpected_rows	Query returned an unexpected number of rows
Cunique_violation
Cusage_error	Error in usage of libpqxx library, similar to std::logic_error
Cvariable_set_to_null	The caller attempted to set a variable to null, which is not allowed
Czview	Marker-type wrapper: zero-terminated `std::string_view`