Use chunked file reading to avoid loading entire files into memory

[JanTvrdik]

Summary

• Added BufferedFileParseTrait with shared logic that reads files in 64 KiB chunks via fopen()/fread() instead of file_get_contents(), so memory usage is proportional to the largest single query rather than the entire file size
• Refactored all three parsers (MySqlMultiQueryParser, PostgreSqlMultiQueryParser, SqlServerMultiQueryParser) to use the trait — no changes to regex patterns or public API
• Includes a safety check to prevent \z regex anchors from falsely matching at chunk boundaries before EOF

Test plan

• All existing tests pass (composer tests — 4 tests, 0 assertions failures)
• PHPStan reports no errors (composer phpstan)
• Verify with a large SQL file (100+ MB) that memory stays bounded

[Copilot]

Pull request overview

This PR refactors the multi-query parser to use chunked file reading instead of loading entire files into memory, aiming to reduce memory usage for large SQL files. The implementation introduces a shared BufferedFileParseTrait that reads files in 64 KiB chunks using fopen()/fread() and refactors all three database-specific parsers (MySQL, PostgreSQL, SQL Server) to use this trait. A safety mechanism is included to prevent false \z regex anchor matches at chunk boundaries.

Changes:

• Introduced BufferedFileParseTrait with chunked file reading logic (64 KiB chunks)
• Refactored MySQL, PostgreSQL, and SQL Server parsers to use the new trait with callback-based pattern processing
• Added safety check to handle \z anchor edge cases at chunk boundaries

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
src/BufferedFileParseTrait.php	New trait implementing chunked file reading with buffering, pattern matching, and memory management logic
src/MySqlMultiQueryParser.php	Refactored to use BufferedFileParseTrait with callback handling for dynamic delimiter changes
src/PostgreSqlMultiQueryParser.php	Refactored to use BufferedFileParseTrait with static callback for query extraction
src/SqlServerMultiQueryParser.php	Refactored to use BufferedFileParseTrait with static callback for query extraction

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[Copilot]

The buffering logic will fail for queries larger than 64 KiB. After reading the first chunk (line 38), if the remaining buffer is >= chunkSize (line 37), the inner loop exits. If preg_match then fails because the query is incomplete (no delimiter found yet), the outer loop breaks (line 52), and a RuntimeException is thrown (line 92).

The fix should ensure that if preg_match fails and we're not at EOF, we continue reading more data instead of breaking. One approach would be to:

1. Always try to read at least one more chunk after a failed match (if not at EOF)
2. Or, change the inner loop condition to ensure we have enough buffer data to match complete patterns

This is critical because the PR's goal is to handle large files without loading them entirely into memory, but it fails for any individual query exceeding the chunk size.

Suggested change

	if (preg_match($pattern, $buffer, $match, 0, $offset) !== 1) {
	if (preg_match($pattern, $buffer, $match, 0, $offset) !== 1) {
	// If no match is found but we're not at EOF, try to read more data
	if (!$eof) {
	$chunk = fread($handle, $chunkSize);
	if ($chunk !== false && $chunk !== '') {
	$buffer .= $chunk;
	$eof = feof($handle);
	continue; // retry matching with more data in the buffer
	}
	$eof = feof($handle);
	}