https://wpxss.com/tricks/use-php-regex-replace-line-by-line-to-remove-malware-from-large-database-dumps/

replace.php

<?php

ini_set( 'pcre.backtrack_limit', '50000000000' );
ini_set( 'pcre.recursion_limit', '50000000000' );

$inputfile = fopen( 'inputfile.sql', 'r' ); // replace this before running
$outputfile = fopen( 'outputfile.sql', 'w' ); // replace this before running
$regex = '/myregex/s';
$lines = 0;

if ( $inputfile ) {
  while ( ( $buffer = fgets( $inputfile ) ) !== false ) {
    $lines ++;
    echo 'Line:' . $lines . PHP_EOL;
    $c = preg_replace( $regex, '', $buffer, -1, $count );
    fwrite( $outputfile, $c );
  }
  if ( ! feof( $inputfile ) ) {
    echo "Error: unexpected fgets() fail\n";
  }
  fclose( $inputfile );
  fclose( $outputfile );
  echo "Done!\n";
} else {
  echo "Input issue!\n";
}