stream

stream :: (
    c: *Connection,
    error: *Pg_Error,
    $sql: string,
    args: ..Any,
    batch := 1000,
    $call := #caller_code
) -> Row_Stream(#run row_type(sql, call, 2, #insert,scope(call) #run row_table_type(sql, call, 2, #insert,scope(call) #run row_table_exists(sql, call, 2)), Row(#run row_shape(sql, call, 2))))

query for results too big to hold: the rows arrive batch at a time and for decodes them one by one, so at most one batch is in memory. The statement is sent here, and the connection is busy until the loop ends; leaving the loop early cancels the rest. A failure, before or during the loop, lands in error (cleared first). Strings in it live until the next batch: copy what you keep.

Not run: it needs a PostgreSQL server.

Parameters

c: *Connection

the connection to run on; it is busy until the loop ends.

error: *Pg_Error

set to the failure, if any, once the loop ends.

$sql: string

the statement, as for query.

args: ..Any

one value per %, in order.

batch := 1000

how many rows arrive at a time.

$call := #caller_code

the code of the call, which lets the query text be checked while compiling. Leave the default.

Returns

Row_Stream(#run row_type(sql, call, 2, #insert,scope(call) #run row_table_type(sql, call, 2, #insert,scope(call) #run row_table_exists(sql, call, 2)), Row(#run row_shape(sql, call, 2))))

error: Pg.Pg_Error;
for Pg.stream(c, *error, "select id, body from events where day = %", day, batch = 5000) {
    total += it.body.count;
}
if error.kind != .NONE ...