php / php/php-src

FETCH_LAZY not properly supported for "long" columns

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#9,828 1 comment 0 reactions 0 assignees View on GitHub

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Bug Extension: pdo_odbc Status: Needs Triage
Dominant language
C
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Description

Description

The following code:

<?php
const SIZE = 300;
$pdo = new PDO(DSN, USER, PASS);
$pdo->exec("CREATE TABLE gh9498 (name VARCHAR(" . SIZE . "))");
$pdo->exec("INSERT INTO gh9498 VALUES ('" . str_repeat("a", SIZE) . "')");
$statement = $pdo->prepare("SELECT * FROM gh9498");
$statement->execute();
$row = $statement->fetch(PDO::FETCH_LAZY);
var_dump($row);
var_dump($row);

Resulted in this output:

object(PDORow)#3 (2) {
  ["queryString"]=>
  string(20) "SELECT * FROM gh9498"
  ["name"]=>
  string(300) "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
}
object(PDORow)#3 (2) {
  ["queryString"]=>
  string(20) "SELECT * FROM gh9498"
  ["name"]=>
  NULL
}

But I expected this output instead:

object(PDORow)#3 (2) {
  ["queryString"]=>
  string(20) "SELECT * FROM gh9498"
  ["name"]=>
  string(300) "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
}
object(PDORow)#3 (2) {
  ["queryString"]=>
  string(20) "SELECT * FROM gh9498"
  ["name"]=>
  string(300) "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
}

Obviously, accessing the row for the first time works as expected, but accessing it another time, does not. If SIZE < 256, accessing the row multiple times is properly supported.

PHP Version

PHP-8.0

Operating System

any

Contributor guide

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Reproduce the example with PDO::FETCH_LAZY and a value longer than 256 characters, then trace the PDO fetch path for repeated row access. Add a regression test covering the reported behavior; done means the long column remains available on the second access, matching the expected output.

Written by the indexing model from the issue text.

Assessment

Tech stack
c, php
Domain
database
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
42/100

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