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Known limitations

These hold for engine 0.2.0, the current release. Engine 0.0.7 adds the differences listed at the end.

  • A lost session takes its state with it. When the engine no longer holds a connection's session, the connection replaces it on the DSN's scope only when nothing of the caller's own went with it; otherwise it throws SessionLostError and the unit of work has to start over. See Session lifetime.
  • A DateTime holds milliseconds. The engine sends timestamps with nanoseconds, but a TIMESTAMP_NTZ and the wall clock of a ZonedTimestamp are Julia DateTimes, so digits beyond the millisecond do not survive. TO_VARCHAR(ts, 'YYYY-MM-DD HH24:MI:SS.FF9') reads them. A TIME keeps its nanoseconds.
  • Fractional numbers arrive as Float64. A NUMBER(38,10) value beyond Float64 precision is rounded; only integral values are read exactly. Read such a column through TO_VARCHAR when the last digits matter.
  • Failures carry no error code. The protocol reports only a message, with no error code or SQLSTATE, so QueryError has none.
  • No Tables.jl interface, since that would add a dependency. result.values is the data and columnnames(result) the header, which is what most table constructors take.

Engine 0.0.7

  • A request may carry any number of statements.
  • Timestamps arrive with millisecond precision and a TIME in whole seconds: a bound Time(1, 2, 3, 456) reads back as 01:02:03. TO_VARCHAR still reads the stored fraction.
  • A TIMESTAMP_TZ arrives at offset +00:00 with the wall clock it was written with, so utc(z) is off by the original offset.
  • An empty statement is refused by the HTTP endpoint with SQL is required.
  • Columns carry no length.
  • An expired session silently resumes at the server's default scope. The engine starts a fresh session under the expired one's id, and nothing in its answer says so. The driver re-applies the DSN's scope to a connection idle longer than idleLimit, but other session state (variables, ALTER SESSION settings) is lost. It stops re-applying once the caller issues their own USE, because the DSN no longer describes the session.
  • Sessions are not released on close. The engine has no endpoint for it, so a closed connection's session remains until the engine's 30-minute idle expiry removes it.