HDBC driver interface for PostgreSQL 8.x

Written by John Goerzen, jgoerzen@complete.org

NOTE ON DATES AND TIMES

The recommended correspondence between PostgreSQL date and time types and HDBC SqlValue types is:

• SqlLocalDate: DATE
• SqlLocalTimeOfDay: TIME WITHOUT TIME ZONE
• SqlZonedLocalTimeOfDay: TIME WITH TIME ZONE
• SqlLocalTime: TIMESTAMP WITHOUT TIME ZONE
• SqlZonedTime: TIMESTAMP WITH TIME ZONE
• SqlUTCTime: TIMESTAMP WITH TIME ZONE
• SqlDiffTime: INTERVAL
• SqlPOSIXTime: NUMERIC
• SqlEpochTime: INTEGER
• SqlTimeDiff: INTERVAL

Other combinations are possible, and may even be converted automatically. The above simply represents the types that seem the most logical correspondence, and thus are tested by the HDBC-PostgreSQL test suite.

A global lock only used when libpq is not thread-safe. In that situation this mvar is used to serialize access to the FFI calls marked as safe.

Connect to a PostgreSQL server.

See http://www.postgresql.org/docs/8.1/static/libpq.html#LIBPQ-CONNECT for the meaning of the connection string.

Provided the local libpq library is thread-safe, multiple Connections may be used to have concurrent database queries. Concurrent queries issued on a single Connection will be performed serially.

When the local libpq library is not thread-safe (ie. it has not been compiled with --enable-thread-safety), only a single database function will be performed at a time.