jtv/libpqxx 7.5.0

libpqxx 7.5.0: more modern, more efficient, more flexible

on GitHub

There are now more ways to pass a BYTEA parameter to a query, and more of them get passed as binary data without intervening encode/decode pass. This last part makes it more efficient, but should not be visible to you otherwise.

When it comes to passing parameters to queries, some people wanted a way to build parameter lists on the fly. This was possible with the old parameter-passing API, but never actually supported. There is now a class for doing this, params, with some optimisation built in to prevent unnecessary copying of string_view and similar values.

"Blobs" (the new BYTEA API) have a new read() method on compilers which support C++20 "spans." It's based on std::span, and you can expect more use of spans soon.

Here's the more complete list:

• Now requires std::variant support! No longer works with gcc7.
• When implementing a string conversion, consider specialising param_format.
• Stop "aborting" nontransaction on closing. (#419)
• Silence an overzealous Visual C++ warning. (#418)
• Starting support for C++20 std::span.
• New blob::read() using std::span. (#429)
• New params class lets you build parameter lists incrementally. (#387)
• Pass std::vector<std::byte> params in binary format.
• Dropped legacy tests 31 and 49 to work around clang C++20 bug.
• Fixed stream_to test failure in non-English locales. (#440)
• Clarify transaction_base::stream documentation. (#423)
• Avoid <thread> on MinGW; it's broken there. (#336, #398, #424, #441)