Looking at the history, this seems to be the only candidate that falls into the timespan: https://github.com/php/php-src/commit/12628e9a46b91a0aa92fd0619cdd545c409d25a6

Thanks for the report. Were you already able to come up with a reproduce code?

Thanks.

Yes, I was able to trim this down today. It's about transactions. Commenting out the transaction statements in the following example makes the script work again:

<?php
$pdo = new PDO('pgsql:dbname=test', 'vagrant', '');
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$pdo->setAttribute(PDO::ATTR_EMULATE_PREPARES, true);
$pdo->query('DROP TABLE IF EXISTS "horde_sessionhandler"');
$pdo->query('CREATE TABLE "horde_sessionhandler" ( "session_id" character varying(32) NOT NULL, "session_lastmodified" integer NOT NULL, "session_data" bytea, PRIMARY KEY("session_id") )');
$pdo->query('CREATE INDEX "index_horde_sessionhandler_on_session_lastmodified" ON "horde_sessionhandler" ("session_lastmodified")');
$pdo->beginTransaction();
$pdo->query('INSERT INTO "horde_sessionhandler" ("session_id", "session_data", "session_lastmodified") VALUES (\'sessionid\', E\'\\\\x73657373696f6e64617461\', 1470745222)');
var_dump($pdo->lastInsertId(null));
$pdo->commit();
$stmt = $pdo->query('SELECT * FROM "horde_sessionhandler"');
var_dump($stmt);
var_dump($stmt->fetchAll(PDO::FETCH_ASSOC));

Thanks for the further research! Nope, it's not the transaction itself, but the changed behavior of lastinsertid() method. The call to $pdo->lastInsertId(null); implies a sequence were used. In this case, the table has no sequence column, so call to the last insert id is the error that ruins the transaction. It can be seen by viewing $stmt->errorinfo().

The PHP code seems to be not correct in first place, as lastinsertid() method should not be called without having a sequence. Therefore the bugfix is correct. But since it breaks the existing code, the question is probably only whether we revert this in the stable branch or some workaround is possible.

Thanks.

@yunosh, i've applied this patch to retain BC in stable branches. Though, it's unchanged in 7.1+, please be aware.

Thanks.

Thanks!