CRM-19968 SQL tweaks to make it more likely that reverting to single language w…

[mattwire]

…ill actually work.
Disabling multiple languages is almost certain to fail on an existing reasonably well populated system due to row size constraints. This patch makes a couple of simple tweaks to the SQL queries so that it is much more likely to succeed!

1. Column is renamed instead of created and copied, as the copy often leads to a row size constraint (eg. in civicrm_event when you have some text in intro_text_lang).
2. Use DROP VIEW IF EXISTS instead of DROP VIEW (supported in mysql 5.1+). There is more support for IF EXISTS on other SQL functions in new versions of mysql but we can't use them if we're maintaining compatibility.

[civicrm-builder]

Can one of the admins verify this patch?

[mlutfy]

jenkins, test this please

[mlutfy]

missing a space after the comma

[mlutfy]

jenkins, test this please

[xurizaemon]

Since you raised the spectre of MySQL 5.1 in JIRA - I'm not fussed, but easy to account for it?

I thought CiviCRM might already have status available to check but it seems we query MySQL for this as we need.

$mysql_version = CRM_CORE_DAO::singleValueQuery('SELECT VERSION()');
foreach ($locales as $loc) {
  if (version_compare($mysql_version, '5.1', '>=')) {
    $queries[] = "DROP VIEW IF EXISTS {$table}_{$loc}";
  }
  else {
    $queries[] = "DROP VIEW {$table}_{$loc}";
  }
}

There might also be a 😱 MySQL comment syntax which <5.1 will ignore? I kinda hate this as it's harder to read, but

foreach ($locales as $loc) {
  $queries[] = "DROP VIEW  /*!50100 IF EXISTS */  {$table}_{$loc}";
}

[eileenmcnaughton]

Yep - it seems we do still support 5.1 https://wiki.civicrm.org/confluence/display/CRMDOC/Installation+and+Upgrades

[xurizaemon]

I see now my initial comment misjudged @mattwire's intent - I believe he's saying we do curerntly support 5.1+ anyway, but we could use IF EXISTS more with later MySQL versions to reduce some of that fragility (which I do think is an issue). I'll open that as a separate ticket in JIRA and copy these notes there.

• https://issues.civicrm.org/jira/browse/CRM-20031

[eileenmcnaughton]

@xurizaemon I think this can be merged? It looks like you reviewed it & @mattwire responded to your review?

[mattwire]

@xurizaemon @eileenmcnaughton I think we agreed that it improved the situation, but highlighted that further improvements could be made to reliability of SQL elsewhere in CiviCRM (and in this particular area of code) for which https://issues.civicrm.org/jira/browse/CRM-20031 was opened. However, as this is an improvement over what was there before it should be merged - @xurizaemon do you agree?

[xurizaemon]

I'm happy with this.

[eileenmcnaughton]

Merging based on @xurizaemon review & comment above