pg_send_query

(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)

pg_send_query — 非同期クエリを送信する

説明

pg_send_query(PgSql\Connection $connection, string $query): int|bool

pg_send_query() は、connection に非同期クエリを送信します。pg_query() とは異なり、 PostgreSQL へ一度に複数のクエリを送信することができ、 pg_get_result() を用いて結果を一つずつ取得することが可能です。

スクリプトの実行は、クエリを実行中もブロックされません。接続がビジーである(すなわち、クエリが実行中である)ことを調べるには、 pg_connection_busy() を使用してください。クエリは、pg_cancel_query() をコールすることによりキャンセルすることが可能です。

ユーザーは複数のクエリを一度に送信することができますが、複数のクエリをビジー状態の接続に送信することはできません。クエリがビジー状態の接続に送信された場合、最後のクエリが終了するまで待ち、全ての結果は破棄されます。

パラメータ

connection

PgSql\Connection クラスのインスタンス。

query

実行するひとつまたは複数の SQL 文。

クエリ内のデータは適切にエスケープする必要があります。

戻り値

成功した場合に true 、失敗した場合に 0 を返します。クエリの結果を確かめるには pg_get_result() を使用します。

変更履歴

バージョン	説明
8.1.0	`connection` は、PgSql\Connection クラスのインスタンスを期待するようになりました。これより前のバージョンでは、リソースを期待していました。

例

例1 pg_send_query() の例

<?php
  $dbconn = pg_connect("dbname=publisher") or die("Could not connect");

  if (!pg_connection_busy($dbconn)) {
      pg_send_query($dbconn, "select * from authors; select count(*) from authors;");
  }
  
  $res1 = pg_get_result($dbconn);
  echo "First call to pg_get_result(): $res1\n";
  $rows1 = pg_num_rows($res1);
  echo "$res1 has $rows1 records\n\n";
  
  $res2 = pg_get_result($dbconn);
  echo "Second call to pg_get_result(): $res2\n";
  $rows2 = pg_num_rows($res2);
  echo "$res2 has $rows2 records\n";
?>

上の例の出力は以下となります。

First call to pg_get_result(): Resource id #3
Resource id #3 has 3 records

Second call to pg_get_result(): Resource id #4
Resource id #4 has 1 records

参考

pg_query() - クエリを実行する
pg_cancel_query() - 非同期クエリを取り消す
pg_get_result() - 非同期クエリの結果を取得する
pg_connection_busy() - 接続がビジーかどうか調べる

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User Contributed Notes 6 notes

down

rw burgholzer is name at deq dot virginia dot gov ¶

15 years ago

Regarding the failure to process them all now, then retrieve the results later, I found that all queries would return successfully if I added a further condition to your while loop in the "stack_query()" method.

By adding:
&& (pg_transaction_status($conn) === PGSQL_TRANSACTION_IDLE ) )

Every query executed with no errors.

<?php
$conn = pg_connect("dbname=dbname host=localhost user=psql ");
if ($conn === FALSE)
  exit("Can't connect to db");

$q = array();
// send some queries
foreach (range(0, 50) as $i)
  stack_query($q, $conn, "SELECT 'query $i' AS str;");
// receive them
while (true)
  {
    $left = stack_query($q, $conn);
    echo "$left left... ";
    $result = pg_get_result($conn);
    if ($left == 0 && $result === FALSE)
      break;
    $row = pg_fetch_assoc($result);
    // depending on race conditions, you wont get all your original queries here.
    echo "got $row[str]\n";
  }

function stack_query(&$queries, $conn, $sql = FALSE)
{
  if ($sql !== FALSE)
    $queries[] = $sql;
  while (count($queries) && !pg_connection_busy($conn)  && (pg_transaction_status($conn) === PGSQL_TRANSACTION_IDLE ) )
    pg_send_query($conn, array_shift($queries));
  return count($queries) + (pg_connection_busy($conn) ? 1 : 0);
}
?>

down

Mikewithme at yahoo dot com ¶

21 years ago

Due to a bug, OLD API does not available with PHP 4.2.0 and 4.2.1.

PHP 4.2.2 will support OLD API again and will be kept long enough.

New API will be available PHP 4.2.0 to later versions. 
yohgaki at php dot net
19-Jun-2002 04:00 
Due to a bug, PHP 4.2.0 and 4.2.1 does not support pg_lo_import() old API. It's fixed in PHP 4.2.2.

BTW, new API will be always available from PHP 4.2.0 to later versions. Older API will be kept long enough, also. 
ceco at noxis dot net
15-May-2002 09:08 
it works for me (php-4.2.1)

not like this

int pg_lo_import ( string pathname [, resource connection])

but 
int pg_lo_import ( resource connection, string pathname )

don't know the reason

down

-1

moodsey211 at gmail dot com ¶

13 years ago

pg_send_query would not stop your script from executing but it would stop the script from exiting. 



Example:



<?php

$con = pg_connect('dbname=payroll');

pg_send_query('SELECT process_payroll()'); // Where process_payroll is a super long process

?>



You would still need to wait for the query to finish before the any display would be sent to the browser. And surprisingly, unlike pg_query this script would not generate the Maximum execution time error.

down

-2

Likeyouover others at hotmail dot com ¶

21 years ago

<?php
// --------- OPEN CONN ---

   $conn = pg_connect("host='127.0.0.1' dbname='test' user='usertest' password='passtest'");

// --------- OPEN FILE ---

   $fp = fopen('logo.gif', "r");
   $buffer = fread($fp, filesize('logo.gif'));
   fclose($fp);

// --------- CREATE - INSERT OID ---

   pg_exec($conn, "begin");

   $oid = pg_locreate($conn);

   $rs = pg_exec($conn,"INSERT INTO test(tipo, images) VALUES('A1', $oid);");
   $handle = pg_loopen ($conn, $oid, "w");

   pg_lowrite ($handle, $buffer);
   pg_loclose ($handle);

   pg_exec($conn, "commit");

// --------- OPEN - INSERT OID ---

   $rs = pg_exec($conn, "SELECT images FROM test WHERE tipo = 'A1';");
   $row = pg_fetch_row($rs, 0);

   pg_exec($conn, "begin");
   $loid = pg_loopen($conn, $row[0], "r");

   header("Content-type: image/gif");

   pg_loreadall($loid);
   pg_loclose($loid);

   pg_exec ($conn, "commit");

// --------- UNLINK OID ---

   pg_exec($conn, "begin");

   $loid = $row[0];
   pg_lounlink($conn, $loid);

   pg_exec ($conn, "commit");

// --------- DELETE OID ---

   pg_exec($conn, "DELETE FROM test WHERE tipo = 'A1';");

// --------- CLOSE CONN ---

   pg_close();
?>

down

-2

Ron Howard ¶

21 years ago

If there is an error in one of your queries, the queries following it will not get executed, and there will *not* be an error message displayed. The only way I can think of to determine if an SQL error happened is to use pg_trace.

Example:

pg_send_query($connection,
    "SELECT id FROM users;
    SELECT * FROM customers;
     [INVALID-SQL-STATEMENT];
    SELECT name FROM countries;");

while ($result = pg_get_result($connection))
    $results[] = $result;

The $results array will only have two items in it.

down

-5

vincentdephily ¶

18 years ago

Note that if you send a query without calling pg_get_result() for the previous one (supposing it has finished and the connection is not busy), the previous query will get discarded.

See for yourself (tested on php4.4.0, postgres8.0.4, Linux/FreeBSD) :
<?
$conn = pg_connect("dbname=template1 host=localhost user=pgsql");
if ($conn === FALSE)
  exit("Can't connect to db");

$q = array();
// send some queries
foreach (range(0, 500) as $i)
  stack_query($q, $conn, "SELECT 'query $i' AS str;");
// receive them
while (true)
  {
    $left = stack_query($q, $conn);
    echo "$left left... ";
    $result = pg_get_result($conn);
    if ($left == 0 && $result === FALSE)
      break;
    $row = pg_fetch_assoc($result);
    // depending on race conditions, you wont get all your original queries here.
    echo "got $row[str]\n";
  }

function stack_query(&$queries, $conn, $sql = FALSE)
{
  if ($sql !== FALSE)
    $queries[] = $sql;
  while (count($queries) && !pg_connection_busy($conn))
    pg_send_query($conn, array_shift($queries));
  return count($queries) + (pg_connection_busy($conn) ? 1 : 0);
}
?>

You will have to write a higher level of abstraction if you want a "send all queries now, receive them later" behaviour.

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