github.com/jackc/pgx/v4

• Fix dbSavepoint.Begin recursive self call
• Upgrade pgtype to v1.0.2 - fix scan pointer to pointer

• Fix pgxpool Rows.CommandTag() infinite loop / typo

Potentially Breaking Changes

Technically, two changes are breaking changes, but in practice these are extremely unlikely to break existing code.

• Conn.Begin and Conn.BeginTx return a Tx interface instead of the internal dbTx struct. This is necessary for the Conn.Begin method to signature as other methods that begin a transaction.
• Add Conn() to Tx interface. This is necessary to allow code using a Tx to access the *Conn (and pgconn.PgConn) on which the Tx is executing.

Fixes

• Releasing a busy connection closes the connection instead of returning an unusable connection to the pool
• Do not mutate config.Config.OnNotification in connect

• Fix statement cache cleanup.
• Corrected daterange OID.
• Fix Tx when committing or rolling back multiple times in certain cases.
• Improve documentation.

v4 is a major release with many significant changes some of which are breaking changes. The most significant are included below.

• Simplified establishing a connection with a connection string.
• All potentially blocking operations now require a context.Context. The non-context aware functions have been removed.
• OIDs are hard-coded for known types. This saves the query on connection.
• Context cancellations while network activity is in progress is now always fatal. Previously, it was sometimes recoverable. This led to increased complexity in pgx itself and in application code.
• Go modules are required.
• Errors are now implemented in the Go 1.13 style.
• Rows and Tx are now interfaces.
• The connection pool as been decoupled from pgx and is now a separate, included package (github.com/jackc/pgx/v4/pgxpool).
• pgtype has been spun off to a separate package (github.com/jackc/pgtype).
• pgproto3 has been spun off to a separate package (github.com/jackc/pgproto3/v2).
• Logical replication support has been spun off to a separate package (github.com/jackc/pglogrepl).
• Lower level PostgreSQL functionality is now implemented in a separate package (github.com/jackc/pgconn).
• Tests are now configured with environment variables.
• Conn has an automatic statement cache by default.
• Batch interface has been simplified.
• QueryArgs has been removed.