Increased data type support for simple protocol. Improved test
coverage of simple protocol. This has the additional advantage of
exercising the text encoders and decoders.
[]string, []int16, []int32, []int64, []int, []uint16, []uint32,
[]uint64, []uint, []float32, and []float64 are now supported in the
simple protocol like they are in the normal usage of the extended
protocol.
It was a mistake to use it in other contexts. This made interop
difficult between pacakges that depended on pgtype such as pgx and
packages that did not like pgconn and pgproto3. In particular this was
awkward for prepared statements.
This is preparation for removing pgx.PreparedStatement in favor of
pgconn.PreparedStatement.
Bug was chooseParameterFormatCode would see that type could handle
binary format so binary format would be chosen. But
encodePreparedStatementArgument would see driver.Valuer first and
would encode with that -- which is text mode. So the server would
receive a text format value when expecting a binary format value.
Discovered while investigating #316
Because reading a record type requires the decoder to be able to look up oid
to type mapping and types such as hstore have types that are not fixed between
different PostgreSQL servers it was necessary to restructure the pgtype system
so all encoders and decodes take a *ConnInfo that includes oid/name/type
information.
Though this doesn't follow Go naming conventions exactly it makes names more
consistent with PostgreSQL and it is easier to read. For example, TIDOID becomes
TidOid. In addition this is one less breaking change in the move to V3.
To aid in composability, these methods no longer write their own length. This
is especially useful for text formatted arrays and may be useful for future
database/sql compatibility. It also makes the code a little simpler as the
types no longer have to compute their own size.
Along with this, these methods cannot encode NULL. They now return a boolean
if they are NULL. This also benefits text array encoding as numeric arrays
require NULL to be exactly `NULL` while string arrays require NULL to be
`"NULL"`.
