Question

I am returning a SETOF from a Postgres FUNCTION to PHP/PDO. Unfortunately, I am getting 2 copies of every row returned.

Here is the Postgres TYPE:

CREATE TYPE marker AS (i BOOLEAN, r DOUBLE PRECISION, la DOUBLE PRECISION, lo DOUBLE PRECISION, n INTEGER);

And the FUNCTION:

CREATE OR REPLACE FUNCTION rl_select_markers (latitude DOUBLE PRECISION, longitude DOUBLE PRECISION) RETURNS setof marker AS $$
DECLARE
ROW marker%ROWTYPE;
BEGIN
    FOR ROW IN SELECT is_male, rate, lat, lon, (EXTRACT(EPOCH FROM CURRENT_TIMESTAMP - created_at)/60)::INTEGER FROM markers 
    WHERE expires_at > CURRENT_TIMESTAMP 
    ORDER BY ST_Distance(ST_Point(longitude, latitude), geog, FALSE) LIMIT 25 
    LOOP
    RETURN NEXT ROW;
    END LOOP;
    RETURN;
END;
$$ LANGUAGE plpgsql;

Here is the relevant PHP:

$dbh = new PDO('pgsql:host=' . $host . ';dbname=' . $db, $user, $pw);
$stmt = $dbh->prepare("SELECT rl_select_markers (:lat, :lon)");
$stmt->bindParam(':lat', $lat, PDO::PARAM_INT);
$stmt->bindParam(':lon', $lon, PDO::PARAM_INT);
$stmt->execute();

$keys = array('i', 'r', 'la', 'lo', 'n');
$markers = array();
while ($lines = $stmt->fetch()) 
{   
    $log->logInfo($log_id . " lines=" . $lines);
    $combined = array();
    foreach ($lines as $line) 
    { 
        $log->logInfo($log_id . " line=" . $line);
        // Remove brackets around $line and put in array
        $vals = explode(",", substr($line, 1, strlen($line)-2));
        // Combine into key value pairs
        $combined = array_combine($keys, $vals);
    }
    $markers[] = array("m"=>$combined);
}

$dbh = null;
$stmt = null;

$log->logInfo($log_id . " Send 200 OK");
sendResponse(200, json_encode(array("mks"=>$markers)), "application/json");

The unexpected behaviour is that each $lines is an array of two copies of the same line.

E.G. When there is one record to return $lines would be an array of 2 strings that are exactly the same. So the above logging will produce:

lines=Array
line=(f,10,51.505601,-0.109917,8)
line=(f,10,51.505601,-0.109917,8)

I understand my inner PHP loop is nonsense but it works. I can see work arounds (such as add a break;)but want to remove the duplication.

I hope I have explained this clearly. Can you see why I am getting these duplicates of every record?

Edit

Following @a_horse_with_no_name’s comment question:

Calling the SQL or the FUNCTION from phpPgAdmin does not produce the duplicate.

Answer 1

I think that you’ve made a mistake thinking that fetch() function would return multiple rows — it always returns one row — an array of columns.

As default $fetch_style is PDO::FETCH_BOTH this array is indexed on both column name and 0-indexed column number and has two elements for every column:

0 => (f,10,51.505601,-0.109917,8)
'rl_select_markers' => (f,10,51.505601,-0.109917,8)

So:

• use fetch(PDO::FETCH_NUM), so you’ll get a number indexed column;
• get rid of foreach ($lines as $line)
• rename variable $lines to $line
• just use $line[0]

Corrected code:

while ($line = $stmt->fetch(PDO::FETCH_NUM)) 
{   
    $log->logInfo($log_id . " line=" . print_r($line,TRUE));
    $combined = array();
    // Remove brackets around $line and put in array
    $vals = explode(",", substr($line[0], 1, strlen($line[0])-2));
    // Combine into key value pairs
    $combined = array_combine($keys, $vals);
    $markers[] = array("m"=>$combined);
}

PHP GOTHA Nr 64372

Even better: I’d use select (rl_select_markers (:lat, :lon)).* query and then just:

while ( $combined = $stmt->fetch(PDO::FETCH_ASSOC) ) {
    $markers[] = array("m"=>$combined);
}